Students Guide to Research Methodology (Undergraduate)

Students'

Guide Research

2102

Alexandria Medical Student Research Association 2102

2012 GUIDE TO HEALTH RESEARCH'STUDENTS

Revise Practical Guide For Health Researchers 2

Massage of Thanks

1. Our Faculty Management especially Prof.Dr. Nagwa Mashaly 2. Prof . Dr. Nadia Zaki…….Pioneer Family

3. Prof .Dr. Soha Rashed Professor of Community . Faculty Of Medicine .Alexandria University

For Her Efforts and providing Scientific Material from which this book is collected

4. All Students and Doctors who participate in this book design



Contents:

1) Research Ethics…………………………………………………….(4)

2) Health Research Methodology……………………………….(5) 2.1 Introduction to Research………………………………………………….(5)

2.2 Steps of Conducting a health Research…………………………………...(6)

2.2. A. Prioritizing and selecting a research topic……………………………(6)

2.2.B. Review of literature and other existing information………………….(7)

2.2.C. Development of a research proposal…………………………………..(8)

3) Study Sample…………………………………………………………(12)

4) Epidemiological Study Design……………………………………(13) 4.1 Descriptive Study…………………………………………………………..(134)

4.2 Clinical Trials………………………………………………………………(33)

5) Writing Scientific Paper ……………………………………………( 38 )

6) Making Scientific Presentation……………………………….(42)

7) Evidence Based Medicine………………………………………..(46)



Research Ethics General ethical principles

Ethics are principles of right conduct.

Responsibility for ensuring that ethical standards are observed in research

rests collectively with the investigators, research institutions, national drug regulatory agencies, editors of medical journals, and funding agencies and

organizations.

Ethical approval by one does not relieve the others of responsibility

Countries and institutions should establish ethical review systems to ensure the protection of potential research participants and contribute to the highest

attainable quality in the science and ethics of health research. Ethics committees should be established, as appropriate, at the national, regional and institutional levels

Ethical considerations throughout the research process

The research process begins with the choice of the research topic, followed by selection of the appropriate research design, development of the

research protocol, writing and submitting a research proposal for funding, implementing the study, description and analysis of the research results, interpretation of the research results, and finally communicating the

research, including its publication.

Ethical considerations apply throughout the research process, and will be

discussed in the relevant chapters.

The objective of this approach is to demonstrate that ethical considerations

are integral components of the research process, and are not a subject to be discussed separately.

In fact, scientific assessment of the planned research is an important part of

the ethical review process. It is unethical to expose subjects to research that is not scientifically sound, is not performed by qualified investigators in

qualified facilities, and is not likely to provide valid scientific answers.



HEALTH RESEARCH METHODOLOGY Learning objectives:

At the end of this session, students will be able to:

1. recognize benefits of engaging medical students in health research. 2. define what a 'Health Research' is.

3. list the major characteristics of research.

4. describe steps of conducting a health research.

5. prepare and present a brief summary of a health research proposal.

6. describe the main components of a research report. Introduction:

Scientific research plays a very important role in our efforts to maintain health and

combating diseases. Research helps us create new knowledge and develop proper tools for the use of existing knowledge. Not only does it enable health care providers to diagnose and treat diseases, research also provides evidence for

policies and decisions on health and development.

Benefits of Engaging Medical Students in Health Research:

Targeting medical students early in their careers is a long-term strategy for

promoting health research in general. Most of the research to date, on the effectiveness of such a strategy, has shown that research experience, as a medical

student, is strongly associated with postgraduate research involvement. Engaging medical students in 'Health Research' will assist them to:

understand the role of research in quality medical practice.

use modern communication and information technology to access and manage medical information.

apply the principles of evidence-based medicine in clinical decision making.

solve health problems.

contribute to the published research output of their faculty.

identify future careers, establish important contacts, and secure better

residency positions.



Even if the experience of doing research as a student does not lead to a later career in academic medicine, research experience can help improve students'

skills in:

searching and critically appraising the medical literature.

independent continued learning.

writing research papers.

What is research?

Research is the systematic collection, analysis and interpretation of data to answer

a certain question or solve a problem. Characteristics of research:

1. It demands a clear statement of the problem. 2. It requires clear objectives and a plan (it is not aimlessly looking for

something in order to come across a solution). 3. It builds on existing data, using both positive and negative findings.

4. New data should be systematically collected and analyzed to answer the original research objectives.

Steps of conducting a health research:

A. Prioritizing and selecting a research topic B. Review of literature and other existing information C. Development of a research proposal

D. Implementation of study: i. Data collection

ii. Data processing and analysis iii. Interpretation of results iv. Final report writing

v. Presenting the results: Scientific publication, presentation at meetings, seminars, workshops or conferences, and presentation

for administrators and policy-makers

A. Prioritizing and selecting a research topic

1.1.1.1.1 Criteria for selecting a research topic:

1. Relevance: The topic you choose should be a priority problem. Questions to be

asked include: How large or widespread is the problem? Who is affected? How

severe is the problem? 2. Avoidance of duplication: Before you decide to carry out a study, it is

important that you find out whether the suggested topic has been investigated

before, either within the proposed study area or in another area with similar



conditions. If the topic has been researched, the results should be reviewed to explore whether major questions that deserve further investigation remain

unanswered. If not, another topic should be chosen. 3. Urgency of data needed (timeliness): Are data urgently needed for decision-

making or developing interventions at various levels (from community to policy)?

4. Political acceptability of study: Is the topic acceptable to high level

policymakers? Or has the topic been the interest and support of the local/national authorities?

5. Feasibility of study: Look at the project you are proposing and consider the

complexity of the problem and the resources you will require carrying out your study. Thought should be given first to manpower, time, equipment and money

that are locally available. 6. Applicability of results: Is it likely that the recommendations from the study

will be applied? 7. Ethical acceptability: We should always consider the possibility that we may

inflict harm on others whi le carrying out research. Therefore, review the study

you are proposing and consider important ethical issues such as:

How acceptable is the research to those who will be studied? Can informed consent be obtained from the research subjects?

Confidentiality of data collected.

B. Literature review

Why is it important to review already available information when preparing for a research?

It prevents you from duplicating work that has been done before. It helps you to find out what others have learned and reported on the

problem you want to study. This may assist you in refining your statement of the problem.

It helps you to become more familiar with the various research methods that might be used in your study.

It should provide you with convincing arguments for why your particular

research project is needed.

The sources of information may include the following:

Text-books in libraries.

Index Medicus, which identify journal articles by subject, author and title .

Computer-based literature searches such as MEDLINE.

Bibliographies, such as those found at the end of books, articles and theses, or prepared as separate documents.

Statistics collected at national, provincial and/or departmental levels.



Opinions and beliefs of key informants (e.g. health managers and community leaders).

C. Development of a research proposal

Contents

I. Title of the research II. Introduction: Background information and Statement of the

research problem (Scientific justification for the study)

III. Research objectives IV. Research hypothesis

V. Methodology VI. Work plan VII. Plan for utilization and dissemination of research results

VIII. References IX. Annexes

I. Title of the research

A good title should be short, accurate, and concise.

It should make the central objectives of the study clear to the reader.

It is important to specify what population will be investigated, and where it

will be conducted. II. Introduction (Background information and Statement of the research

problem)

This section should convince the reader of the relevance of the study (magnitude, severity of the problem). It should provide enough background data for an outsider to understand the different aspects of the problem, or the different factors

influencing the problem and the context in which it occurs. Your review of available literature and reports should further i llustrate why the problem is important, not only

in your own working area but probably also beyond. A logical sequence for presenting the statement would be:

Magnitude, frequency, and distribution: Affected geographical areas and population groups affected by the problem.

Probable causes of the problem: What is the current knowledge of the

problem and its causes? Is there agreement? Is there controversy?



Possible solutions: In what ways have solutions to the problem been attempted? What has been proposed? What are the results?

Unanswered questions: What remains to be answered? What areas have

not been possible to understand, determine, verify, or test? III. Research objectives

Research objectives are the goal to be achieved by a research.

- Why should research objectives be developed? The formulation of

objectives will help you to:

1. Focus the study (narrowing it down to essentials) 2. Avoid the collection of data which are not strictly necessary for

understanding and solving the problem you have identified

3. Organize the study in clearly defined parts or phases

- Properly formulated, specific objectives will facilitate the development of your research methodology and will help to orient the collection, analysis, interpretation and utilization of data.

- How should you state your objectives?

Research objectives must be: S-M-A-R-T

Specific Measurable

Attainable Relevant Time-bound

- Formulation of General and specific research objectives

The 'general objective' of a study states what researchers expect to

achieve by the study in general terms.

It is advisable to break down a general objective into smaller, logically connected parts. These are normally referred to as 'specific objectives'.

Specific objectives should systematically address the various aspects

of the problem, and the key factors that are assumed to influence or cause the problem. They should specify what you will do in your

study, where and for what purpose.



IV. Research hypothesis

A hypothesis can be defined as a prediction or explanation of the relationship

between one or more independent variables (PREDISPOSING/RISK FACTORS) and one dependent variable (OUTCOME/CONDITION/DISEASE)). A hypothesis,

in other words, translates the problem statement into a precise, clear prediction of expected outcomes. It must be emphasized that hypotheses are not meant to be haphazard guesses, but should reflect the depth of knowledge, imagination and

experience of the investigator. Therefore, in the process of formulating hypotheses, all variables relevant to the study should be identified.

Example: Health education involving active participation by mothers will produce more positive changes in chi ld feeding than health education based on lectures.

Independent variable (predisposing factor): types of health education. Dependent variable (outcome): changes in child feeding.

V. Methodology

This section summarizes the most important points of the research design

including:

Variables: It is necessary to identify the variables that will be involved in the

research project being designed. Four types of variable are important in research: Independent (predisposing/risk factors), Dependent

(outcome/condition/disease), Confounding, and Background variables. It is also necessary to specify whether these variables are Numerical

(continuous/discrete), or Categorical (ordinal/nominal). Operational definition of different study variables should be clearly phrased.

Study design: Descriptive (e.g. cross-sectional surveys), Analytic (e.g.

cohort and case-control), Experimental strategies (e.g. clinical and preventive trials).

Study population, Selection Criteria, Sample Selection and Size, Sampling method.

Study Setting.

Data Collection Procedures, data collection tools (e.g. questionnaire or

interview schedule, clinical examination, laboratory tests, screening procedures, records, etc.).

Plan of Data Processing and Analysis: This should include the plan for

processing and coding data, either by manual sorting, machine sorting, or computer programme, and choice of statistical methods to be applied to

each hypothesis. Ethical Considerations: e.g. Ethical approval, Informed consent form.

Pre-Testing the methodology (Pilot Study): It may be possible to pre-test:

- The reactions of respondents to the research procedures and to questions related to sensitive issues.

- The appropriateness of study type and research tools selected for the purpose of the study.



- The appropriateness of format and wording of questionnaires and interview schedules and the accuracy of the translations.

- The time needed to carry out interviews, observations or measurements.

- The feasibility of the designed sampling procedures. - The feasibility of the designed procedures for data processing and

analysis.

VI. Work plan

- A work plan is a schedule that summarizes, in a clear fashion, various components of a research project and how they fit together.

- It should include:

1. The various tasks to be performed

2. When the tasks will be performed 3. Who will perform the tasks

VII. Plan for utilization and dissemination of research results

- The proposal should indicate what reports or other means of disseminating

research findings are planned.

- Any or all of the following are appropriate for disseminating the results o f the study:

Progress reports

Final report

Publications

Seminars, workshops, and conferences

Discussion with policymakers and program managers

VIII. References

The references in your text can be numbered in the sequence in which they appear in the report and then listed in this order in the list of references (Vancouver system).

Please refer to the 'Reference' section of the final report described below.

IX. Annexes

These may include:

- Interview schedule/ questionnaires (and/or other data collection tools).

- Informed consent form - Institutional/Ethical approval for the study



Study Sample Target population and accessible population

An important issue in the design of the research is the question of sampling. Ideally, the study design should include all the target population. The term

population in scientific methodology refers to the material of the study, whether it is human subjects, animals or inanimate objects

Types of sampling

The sample selected from the accessible population should be representative of the accessible population. It should accurately reflect the characteristics of the

population from which it is drawn. It should be a miniaturized representation of the accessible population.

Sample size

The desired sample size is now easily calculated with the help of computer statistical programs, but the principles underlying the calculation, and the

limitations must be clearly understood by investigators



Epidemiological study design

Learning objectives: By the end of this session, students will be able to:

1. Classify different types of epidemiological study designs

2. Distinguish between the information provided by, and uses of, descriptive,

analytical and intervention studies.

3. Draw a flow chart for describing the design/steps of different epidemiological

studies.

4. Identify the uses, advantages and disadvantages of different types of

epidemiological study designs.

5. Choose the most suitable study design to the research purpose.

6. Calculate incidence and prevalence rates from tabulated data.

7. Calculate and interpret different risk measures (the relative risk, attributable

risk and odds ratio).

Epidemiological study designs

What types of epidemiological studies are there?

Generally, epidemiological studies are used to provide information on three areas: • on the distribution and frequency of diseases, and on the frequency and

distribution of known and possible causes of diseases in populations – such studies are usually called descriptive;

• on the strength of associations between diseases and other factors

(such as smoking, diet or socio-economic status), with particular emphasis on whether such associations are causal – such studies are usually called analytical;

• on whether interventions aimed at preventing a disease or improving its outcome actually do so – such studies are usually called intervention studies.



Within these three broad categories several types of study can be identified. These are summarized in Table 1.

Table1. Classification of epidemiological study designs

Main category Types within category Presence of a control

(Comparison) group

I. Observational (Non- intervention) studies:

A. Descriptive

studies

based study: -Population

Correlation

(Ecological) study

based study: -Individual

Case report

Case series

Cross-sectional study

Absent

B. Analytical studies Case-control

study

Cohort study

(prospective

and

retrospective)

Present

II. Intervention (Experimental)

studies

Clinical trial

Community

trial

Present

1. Observational (non-intervention) Studies

A. Descriptive studies:

What are descriptive studies used for and what types are there? Uses of descriptive studies

Descriptive studies are used to provide information on the frequency of health states and their known and possible causes by person, place and time. Such



information is crucial to guide the planning of health promotion and disease prevention activities, to guide the planning of health services and may also

provide important clues as to the causes of different health states. Some of the factors to consider under the headings of person, place and time are outlined

below. Person – e.g., for a certain health state, how old are the people who get it?, what sex are they?, what is their socio-economic status?, what is their

occupation?, what is their ethnic group?, what are their lifestyles?, such as smoking and diet, and so on?

Place – e.g., is the occurrence of the health state more frequent in some geographical areas than others, such as between countries, areas within countries or areas within cities?; do members of an ethnic group who have a

low rate of the disease in one area also have a low rate when members of that ethnic group move to another area, and so on?

Time – e.g., has the frequency of the health state changed over long periods of time, such as several years?; does the frequency of the disease vary throughout the year, and so on?

Types of descriptive studies

Correlation studyA1.

Correlation study is referred to as ecological study because the analysis is at

the level of an entire population rather than at the individual level .The

correlation studies measure the association between two quantitative variables.

The value that represents the correlation coefficient (r) lies between -1 (strong

negative correlation) and +1 (strong positive correlation). A value of zero means

no correlation.

Examples of correlation studies:

1. The correlation between the average consumption of meat and the rate of

cancer colon in woman from a large number of countries. Countries with the

lowest average meat intakes have the lowest rates of cancer colon and vice

versa (positive correlation).



2. Correlation between the per capita cigarettes' sales and the mortality from

lung cancer (positive correlation).

3. Correlation between the percentage of decline in mortality from cancer

cervix during a specific period and the percentage increase in the number of

women who screen for cervical cancer (negative correlation).

4. Correlation between the consumption of pork meat in different countries and

the number of cases of breast cancer (positive correlation).

Advantages:

1. Easy, cheap and quick.

2. Use information already available.

3. Useful in formulating hypothesis.

Disadvantage:

1. Inability to link a particular exposure to a particular individual.

2. Inability to control for confounding factors.

A confounding factors is one that affects both the exposure and the disease-that

is (has an association with both the disease and the risk factor under study) that

may distort relationships between the two and confound (confuse) the study

results.



Example: In a study of the association between tobacco smoking and lung cancer,

age would be a confounding factor if the average ages of the non-smoking and

smoking groups in the study population were very different, since lung cancer

incidence increases with age.

Another example: the possible association between meat consumption and

cancer colon may be due to other accompanying factors such as decreased intake

of vegetables or increased intake of fat rather than the meat consumption itself.

A2. Case report and case series

Case report describes a new unusual or interesting phenomenon in a

single case.

Example 1: In 1961, pulmonary embolism has been described in a 40 years, pre -

menopausal females after 5 days of using oral contraceptive pills. This

phenomenon was considered interesting as pulmonary embolism usually occurs

among older subjects, post menopausal. The investigator formulated a hypothesis

that oral contraceptive pills might be responsible for the occurrence of pulmonary

embolism in pre-menopausal females.

Example 2: Adenocarcinoma of the vagina was reported in a young girl. This

tumor is not only rare, but also the usual victim is over 50 years of age.

Documents showed that this girl was exposed to estrogen during fetal life. A

detailed report about this unusual event and exposure was published in a medical

journal. The investigator formulated a hypothesis that fetal exposure to estrogen

may have been responsible for the rare occurrence of this tumor.

Case series describes a new unusual or interesting phenomenon

collected from individual case reports.



Example1: During 1981, five cases of pneumocystitis carinii pneumonia were

reported among young previously healthy, homosexual men in Los Angeles within

a 6-months period. This case series report was unusual as this type of pneumonia

had previously occurred only in older cancer patients whose immune systems were

suppressed, usually as a result of chemotherapy. These unusual circumstances

suggested that these individuals were actually suffering from a previously unknown

disease, subsequently called Acquired immunodeficiency Syndrome (AIDs). As

these cases were all identified in young homosexual men this formulated the

hypothesis that some aspects of sexual behaviors could be related to this disease.

Example2: Kaposi sarcoma, a disease of old age, has been reported among

young adult homosexual men who proved later on to be suffering from AIDs.

Advantages:

1. Easy, cheap.

2. Useful in formulating hypothesis.

3. Individuals in the case series may serve as cases in a case

control study.

Disadvantages:

1. Based on the experience of a single individual and it might be a coincidence.

2. Problem of finding a suitable comparison group.

A3. Cross-sectional study (prevalence study)

Exposure (E) and disease (D) status are assessed simultaneously among

individuals in a well-defined population.

Examples:

1. Assess the presence of ischaemic heart disease (IHD) in relation to high fat diet.

2. Assess the presence of obesity in relation to diabetes mellitus.

3. Assess the presence of thrombophlebitis in relation to the use of oral

contraceptive pills.

4. Health interview questionnaire inquires into all health and health related-

problems as well as all possible personal and socio-demographic factors.

The flow chart of cross-sectional study



No exposure and no disease

The prevalence rate is calculated

as follows:

Example:

A representative sample of men above 60 years in a city x during the year 2004

(N=200) were asked about smoking habit and examined to detect all new and old

cases of coronary heart diseases (CHD). The data are presented in the following

flow chart and table.

Table 1: Distribution of men above 60 years age (n=200) in City X according to

smoking and coronary heart diseases in year 2004.

Smoking habit With (CHD) Without (CHD) Total

Yes 10 30 40

No 8 152 160

Total 18 182 200

The total number of all cases (old and new) in certain area at a given The prevalence rate =X 100time

The number of population in the same area and time

Reference Population

Sampl

e

Exposure and disease

Exposure and no disease

No exposure and disease



The prevalence of CHD among the smokers =(10/40) X 100 = 25%

The prevalence of CHD among non-smokers = (8/160) X100 = 5%

Epidemiologically, the prevalence rate of CHD among smokers (25.0%) is more

than that among non smokers (5%). To find whether the differences observed are

statistically significant or due to chance, the researcher has to use the appropriate

statistical analysis. (Refer to testing hypothesis in Biostatistics).

Advantages:

1. Quick, easy and cheap.

2. Reveals the distribution of health and disease status.

3. Direct case finding.

4. Estimates prevalence rate in relation to exposure.

5. Shows case load.

6. Provides information for planning and evaluation of

health services.

7. Generates hypothesis.

Sample of men above

60 years N =200

Smokers without

(CHD) N=30

Non-smokers with

(CHD) N=8

Non-smokers

without (CHD)

N =152

Smokers with

(CHD) N= 10



Disadvantages:

1. Not useful in rare conditions.

2. Not useful in acute disease

3. Deals only with survivors (survival bias).

4. Fails to demonstrate the temporal relationship (Chicken- egg

dilemma).

It is difficult to determine if the characteristic preceded the condition or vice versa.

B. Analytic studies:

In the analytical studies, the investigator observes the natural course of events. If

he begins with who are exposed and not exposed, it is a cohort study. If he begins

with those who have the disease and those who have not, it is a case control

study. In the analytical studies the use of an appropriate comparison group

allows testing the hypothesis.

Types of analytic studies:

1. Case-control studies.

2. Cohort studies:

a. Prospective cohort.

b. Retrospective cohort.

B1. Case-Control Study

study in which individuals are intervention) analytic -vational (nonobserIt is an

selected on the basis of having the disease (cases) or not having the disease

(controls), and then compared in relation to the presence or absence of a particular

exposure.

Steps of conducting a case control study

This includes: Selection of cases: -1

a. Set the selection criteria (standard case definition): before selection of

cases, criteria of diagnosis should be put e.g. the criteria of diagnosis of



myocardial infarction are electrocardiograph abnormalities, enzyme

changes and characteristic chest pain.

b. Sources of cases: This includes:

Hospitals: all cases admitted during a specific period of time or a

random sample is selected for the study. Selection of cases from

hospitals is associated with a selection bias as it reflects the

characteristics of a group of patients attending a specific facility.

General population: a survey is carried out to identify the cases in

certain area within a specific period of time. The main advantage is

that population based study allows the generalization of the findings

to the whole population yet, it is very costly and not routinely

conducted in terms of searching for cases.

Selection of controls: -2

a. Set the selection criteria (inclusion and exclusion criteria).

b. Identify the source of control (hospital, neighbors, friends, relatives, general

population using population list).

Advantages and disadvantages of different sources of controls

Advantages Disadvantages

Controls from hospital

- Accessible - Over presentation of risk factors

among selected subjects

- Share same criteria (socio-demographic) - By definition, they are sick

- Abolish recall bias

- Willing to cooperate (minimize non response

Controls from the general population

- Healthy - Time consuming

- Very costly



- Population list may be not available

- Recall bias

- Non response bias

Controls from special groups (neighbors,

friends, relatives)

- Healthy

- Share same characteristics (genetic, diet, socio-

demographic factors)

- Willing to cooperate

c. Matching: is the process in which we select the controls in a way that they

are similar to cases with regards to certain confounding factors (e.g. age)

which are known to influence the outcome of the disease.

d. Size of the control: choose at least one control for each case. Increasing

the size of control group increases results' precision. However 4 controls

for every case increase the cost with little increase in precision.

y using the same methodology for both Determine the exposure under stud -3

:cases and controls

1. Review of records.

2. Interview.

Analysis and interpretation of the results: -4

a. Tabulation of data.

b. Calculation of exposure rates among cases and controls.

c. Estimation of the disease risk associated with exposure (odds

ratio).



a. Tabulation of data

b. Exposure rates

The rate of exposure among the cases=

x100 X100 = a/a+cThe number of those exposed among the cases

2 The total number of cases

1.2.2.2.2.2.2.2

1.2.2.2.2.2.2.1 The rate of exposure among the controls=

X100 = b/ b+d x100The number of those exposed among the control

The total number of control

c. Estimation of risk associated with exposure (Odds Ratio)

Odds ratio is the measure of the strength of the association between the risk factor and the

disease. The odds ratio is the cross product of the entries of the previous table

OR= a x d

c x b

If the value of odds is:

More than one= there is a risk.

Less than one= the exposure factor is protective.

Equal one= there is no relation between the exposure factor and the disease.

Exposure Disease status

Cases Controls

Yes a b

No c d

Total a+c b+d



Example:

An investigator selected 100 patients with CHD admitted to X hospital during the

year 2004, and 100 subjects free from the disease as a control from general

population. Both groups were interviewed to obtain information on history of

smoking. The smokers were 60 among cases and 20 among the control.

The flow chart of case-control study

(60) Smokers (E1)

(40) Non smokers (E0)

(20) Smokers (E1)

(80) Non smokers (E0)

Past Present

The direction of the study

Distribution of CHD patients admitted to X hospital and their controls during

the year 2004 according to smoking habit.

Smoking habit Patients With

(CHD)

Controls free from

(CHD)

Exposed (E1) 60 20

None exposed (E0) 40 80

Total 100 100

Exposure rate of smoking among the cases= 60X100 = 60%

100

Exposure rate of smoking among control= 20X100 = 20%

Patients CHD (N=100)

Controls (N=100)



100

This shows that the frequency of smoking among the cases is more than that

among the control (60% > 20%). So there is an association between CHD and

smoking. The next step is to show whether there is a statistical association

between exposure status and occurrence of CHD (Refer to Chi-square test in

Biostatistics).

Calculation of Odds ratio:

Odds Ratio = 60X80 = 6

20X40

Interpretation of the Odds ratio:

- CHD patients tended to be smokers six times greater than those without CHD.

OR

- It is six times more likely to find prior exposure to smoking among patients with

CHD than among those without CHD.

B2. Cohort Studies

Prospective Cohort Study:

, and follow exposed-nonor exposedSelection of individuals on basis of being

them for a certain duration of time to determine whether or not the disease

developed.

Steps in conducting a prospective cohort study

Selection of population: -1

a) Selection of exposed

1. Selection of exposed from the general population if the exposure is

common as smoking, obesity, sedentary life.

2. Selection of exposed from a specific group when exposure is not

common or rare as:

- Population subgroups: People living in oasis, people living near a

source of pollution



- Certain occupation: Uranium miners, welders, rubber industry,

radiologists.

b) Selection of non-exposed or comparison group

Selection of cohort depends on exposure:

- If the exposure is common the cohort will be selected from the general

population and this is a heterogonous group. Either all the population or a

representative sample is selected. According to the exposure they are

classified as the study group i.e. the exposed (smokers) and the comparison

group i.e. not exposed (non smokers). Both are then compared according to

subsequent morbidity (CHD) or mortality. This is called internal comparison.

Example: Exposure to smoking in the population

- If the exposure is rare (exposure to radiation) the study subjects will be

selected from a homogenous group as they are all experienced a similar

exposure (e.g. radiologists exposed to X ray). Then the study subjects

should be compared with external group who are not exposed this is called

external comparison. Example: A cohort of radiologists is compared with a

cohort of ophthalmologists.

2- Obtain data on exposure:

- From the subjects themselves.

- Medical records.

- Medical examination.

- Laboratory investigations.

- Environmental surveys.

3- Follow up the two cohort for the whole latency period.

Obtain data on outcome: -4

- Death records.

- Medical records.



- Medical examination.

- Laboratory investigations.

(All procedures should be standardized for all participants in the two groups).

4- Analysis and interpretation:

Exposure Disease status

Total Diseased Healthy

Yes a b a+b

No c d c+d

1. Calculate the incidence rate among exposed (a/a+b) x constant.

2. Calculate the incidence rate among non-exposed (c/c+d) x constant.

3. Calculate the relative risk (RR). RR indicates how many times those

exposed are likely to develop the disease relative to non-exposed.

Incidence rate among exposed =

Incidence rate among non-exposed

4. Interpretation of the RR:

< 1: the exposure is protective.

> 1: the exposure is a risk.

= 1: the exposure is not associated with the disease.

5. Calculate attributable risk percent (ARP):

The ARP indicates to what extent the disease under study is attributed to the

exposure. ARP is the difference between the incidence rate of the disease

among the exposed (Ie) and that among the non exposed (I0) expressed as a

percent. ARP = (Ie) - (I0) X 100

(Ie)

Example: A group of male individuals are classified according to their smoking

habit into smokers (n=200) and non-smokers (n=200). The two groups are similar



in all other aspects as age education, and social class. They are followed up for

ten-year period. CHD are detected among 20 of the smokers and among 2 non-

smokers.

The flow chart of prospective cohort study

CHD ( N=20) (a)

No CHD (N=180) (b)

CHD (N=2) (c)

No CHD (N=198) (d)

Present Future


Tabulation of data:

Distribution of the cohort groups (Smokers and non-smokers) according to

the detected CHD after a ten year follow up period.

2.1.1.2 Smoking

habit

Patients with

(CHD)

Free from

(CHD) 2.1.1.3 Total

Exposed (Ee)

(Smokers)

(a)

20

(b)

180

(a+b)

200

None-Exposed (E0) (c) (d) (c+d)

Exposed (Ee) (Smokers) (N=200)

(a+b)

None Exposed

(E0) (Non-Smokers)

(N=200) (c+d)



(Non-smokers) 2 198 200

The incidence of CHD among smokers (Ie) = a X100 = 20 X100 = 10%

a+b 200

The incidence of CHD among non smokers (I0) = c X100 = 2 X100 = 1%

c+d 200

Estimation of risks:

RR = (Ie) =10 =10

(I0) 1

RR= 10 indicates that smokers are ten times at greater risk of developing CHD

than non-smokers.

ARP = (Ie) - (I0) X 100 = (10 - 1) X100 = 90%

(Ie) 10

This indicates that 90% of the CHD among smokers is attributed to smoking i.e. 90

% of CHD among smokers could be prevented if smoking is eliminated.

Retrospective Cohort Study:

In retrospective cohort study, the investigator goes back years to select the study

subjects (exposed to suspected factor, Ee) and the comparison group (not exposed

to suspected factor E0) from the existing records. Then their medical records are

examined starting from the fixed past date till present to detect those with or

without the disease of interest. The retrospective cohort studies are useful for

occupational exposures, because the recorded information is available.

Example: During the year 2000, an investigator conducted a retrospective cohort

study to show the causal association between exposure to asbestos and

occurrence of lung cancer. A group of workers exposed to asbestos was identified

from the factory records beginning from the years1980. Those reported to have



lung cancer from the year 1980 ti ll the present (2000) were identified. They were

compared with a group of other workers not exposed to asbestos. The result of this

comparison showed more lung cancer cases are found among asbestos workers.

Lung cancer

No lung cancer

Lung cancer

No lung cancer

Past Present


The main differences between the prospective and retrospective cohort

Prospective cohort Retrospective cohort

- The exposure may or may not have

occurred at the time of the study but the

disease definitely didn't occur

- Both exposure and disease have occurred

and the investigator has to make sure that

the exposure occurred before the disease

status

- It begins in the present and continue in the

future

- It begins in the past and continues to the

present

- Time consuming - Saves time

- Expensive - Cheap

Benefits of cohort studies:

- It is of value when the exposure is rare.

- Can examine multiple effects of single exposure (smoking is a factor that results

in CHD, cancer lung, cancer mouth, cancer esophagus, peptic ulcer and

hypertension…etc).

Exposed to asbestos (Ee)

Not-Exposed to asbestos

(E0)



- The incidence of the disease among the exposed and non-exposed can be

calculated.

- It provides a direct estimate of relative and attributable risk.

- Dose response ratio can be calculated.

- No selection bias, since exposure is assessed prior to the occurrence of the

disease, so the outcomes could not influence the selection of the exposure

(compared to case control study).

- It allows testing the hypothesis, as the cohort groups are free from the studied

disease at the beginning of the study, the temporal consequence between the

exposure and the disease can be proved (no chicken egg dilemma).

Limitations of both types of cohort studies:

-They are not suitable for evaluation of rare diseases.

Limitations of prospective cohort study:

- Loss of experienced staff, loss of funds.

- Change in the environmental factors.

- Change in standard diagnostic methods or criteria of diseases.

- The study itself may alter the participant‘s behavior.

- Attrition problem: loss of the participants (migration, deaths, lack of interest)

during the follow up affects the validity of the results

- Ethical problems.

- It is expensive and time consuming.

Limitations of retrospective cohort study:

The records are not available and incompleteRetrospective cohort is not accurate.



Advantages and disadvantages of case-control and cohort studies

I. Intervention (Experimental) studies

An intervention trial is a follow-up study in which the

intervention (or the primary exposure) under study is applied

by the investigator.

Aspect Case- control Cohort

Logistics of the study

1. Time Quick Long

2. Cost Relatively cheap Expensive

3. Sample size Small Larger

4. Ethical problem - Present

Type of investigation

1. Rare disease Best -

2. Disease with long latency period Best -

3. Rare exposure - Best

4. Multiple outcome - Best

5. Several risk factors best -

Problems

1. Selection bias Always present -

2. Recall bias Present -

3. Temporal relationship Not certain Certain

4. Attrition problem Little Problematic

5. Change in environment, behavior Not a problem Problematic

Measurements

1. Incidence rate Can not be calculated Can be calculated

2. Relative risk Approximation (OR) Can be calculated

3. Attributable risk Can not be calculated Can be calculated

4. Dose response relationship Can not be determined Can be determined



Intervention (Experimental) studies are the best

epidemiological study design to prove causation of a disease,

or to determine the effectiveness of a vaccine, therapeutic

drug, or a surgical procedure.

Two types of intervention studies, the randomized clinical trial

(RCT) and the community trial (CT) are discussed in this

section.

A. Randomized clinical trials (RCTs)

experimental one group of individuals receive an intervention (clinical trial In a

), and are compared to another group who do not receive the intervention group). groupcontrol (

The flow chart of randomized clinical trial

Clinical trials are often divided into two types: therapeutic trials, and preventive trials:

- Therapeutic trials are conducted among patients with a particular disease

or health problem to determine the ability of an intervention (such as a therapeutic drug, surgical procedure, special diet, or psychological

counseling, etc.) to reduce symptoms, prevent recurrence, or decrease the risk of death from that disease.



- A preventive trial is used to evaluate whether an intervention (e.g. vaccine,

smoke-free environment) reduces the risk of developing a disease among

those who are free from it when they enter the trial.

Essential principles (features) of properly designed clinical trials: 1. Control of variables surrounding the experimental subjects

The investigator has control of the subjects, the intervention, outcome

measurements, and sets the conditions under which the experiment is conducted. In particular, the investigator determines who will be exposed to

the intervention and who will not. This selection is done in such a way that the comparison of outcome measure between the exposed and unexposed groups is as free of bias as possible.

2. The use of control (comparison) group which receives placebos (blank

doses or treatments such as saline injection or sugar pill). In order for a treatment regimen to be considered effective, or for a factor to be considered causally related, it must significantly affect the experimental

group differently (usually determined using a statistical test) from the control group.

3. Randomization refers to the practice of assigning subjects to experimental

or treatment groups in a completely random manner. Thus each subject has

an equal chance of being placed in the experimental group. This avoids the potential bias of the researcher choosing subjects s/he feels would be most

likely to benefit from the intervention for the intervention group, and a similar possible bias if the choice were left up to the subjects.

4. Blindness refers to the practice in which the researcher remains

uninformed and unaware of the identities of experimental and control groups

throughout the period of experimentation and data gathering. Thus, the researcher can remain unbiased in judging the responses of any particular subject or group.

When studies involve human subjects, it is important that the subjects also

remain uninformed as to whether they have been placed in the experimental group (receiving the treatment) or control group (receiving the placebo). Such procedure is referred to as double-blind (neither researcher nor

subjects know who is receiving the treatment). This is important because some people begin to feel better if they believe they have received a

treatment. Only at the end of the study would the ‗code‘ (known by the statistician) be broken and the results analyzed according to who had been taking the drug and who had not.

So, the gold standard design for clinical trials, i.e., the least prone to bias, is the randomized double-blind controlled trial.

.Example



Imagine that you wish to compare the effectiveness of a new anti-cancer drug with a current treatment. A group of patients would be randomly assigned to receive the

new drug (group A), and the remainder would be given an existing drug (group B). Detailed records would be maintained on factors such as length of survival, side-

effects experienced and quality of life. At the end of the trial, the results for group A would be compared with those for group B, and conclusions would be drawn as to which drug was the most effective one.

Usually two groups of subjects are studied - those who receive the treatment of

interest and those who do not. However, some trials use three or more groups. Very often, a new treatment will be compared with an existing one, or even with a non-treatment (a placebo). Analysis of data in Randomized Clinical Trial

The

Outcome

+ -

The

Intervention

+ a b

a / (a+b)

Risk Rate of

Developing

Outcome in

intervention

group

Relative Risk

(Risk Ratio)

[a / (a+b)]

= ---------------

[c / (c+d)]

Absolute risk reduction=

[a/(a+b)]-[c/(c+d)]

---------------

- c d

c / (c+d)

Risk Rate of

Developing

Outcome in

control group

Advantages of Randomized Clinical Trials

Provides the strongest evidence for causality as it: - Ensures temporal relationship between exposure and outcome. - Controls for confounding through randomization; thus the two groups are

exactly similar to each other except for the exposure of interest.

The best epidemiological study design to determine the effectiveness of a

vaccine, therapeutic drug, or a surgical procedure.

The least prone to biases related to selection and measurement.

Disadvantages of Randomized Clinical Trials



Expensive, time consuming and complicated to perform.

In many situations, especially those which concern study of ―risk factors‖ or

―prognostic factors‖, one cannot ―randomly‖ allocate human beings into two groups; e.g. in studying the relation between smoking and lung cancer, we

cannot randomly divide human beings into two groups and ensure that one group smokes while the other does not.

Sometimes it is ethically questionable. Even when ―random allocation‖ is possible, it may not be ethical to randomly divide, thus exposing the ‗exposed‘ group to a potentially harmful treatment or procedure; or to

deprive the ‗non exposed‘ group of a potentially useful measures.

Patients may refuse treatment. Non-compliance can affect results.

A large sample size is needed.

B. Community trials (CTs)

. its of study are communities rather than individualsthe unIn a community trial,

This is particularly appropriate for diseases that have their origins in social, cultural or environmental conditions, where it makes sense to try and change these conditions on a community-wide basis rather than an individual basis. Examples

- An example of a community intervention trial would be testing a vaccine.

Some communities will be randomly assigned to receive the vaccine, while other communities will either not be vaccinated, or will be vaccinated with a placebo.

- Another example would be a test of whether the introduction of iron-fortified

salt in the community would reduce the incidence of anaemia in the community.

- A community trial aimed at changing diet might include widespread information campaigns using the local media, as well as measures to

increase the availability of healthy foods in the local shops.

Review questions

1. In a descriptive epidemiological study, what types of information does the epidemiologist gather?

2. What is the purpose of an analytical study? Contrast case-control and cohort studies in regard to methodology (design) and usefulness.

3. How do intervention (experimental) studies differ from analytical

studies? What value do they have in epidemiology? To what four

principles must researchers adhere in order to properly carry out an intervention study?



4. Choose the best study design you would use to do the following: a) evaluate whether a new drug is effective in treating a condition

b) examine the cause of death by age, sex and area of residence for people living in Egypt last year

c) measure the amount diabetic cases in a population d) examine whether people exposed to an unusual industrial

chemical are at an increased risk of developing certain diseases

e) determine whether a mass media campaign to encourage people to change an aspect of their life style is effective

f) identify possible causes of a rare disease

Final Report Writing

Main components of a research report:

I. Title or cover page

II. Abstract III. Introduction

IV. Objectives V. Methodology VI. Research results (findings)

VII. Discussion VIII. Conclusions IX. Recommendations

X. References XI. Annexes or appendices (data collection tools, tables)

I. TITLE OR COVER PAGE

Cover page includes: research title, names of the authors with their titles and positions, and the institution that is publishing the report.

The research title could consist of a challenging statement or question, followed by an informative subtitle covering the content of the study and indicating the area

where the study was implemented.

II. ABSTRACT (SUMMARY)

The abstract/summary should be written only after the final draft of the report has been completed.

It should contain:

- a very brief description of the problem (WHAT) - the main objectives (WHY) - the place of study (WHERE)

- the type of study and methods used (HOW) - major findings and conclusions



- the major recommendations

III. INTRODUCTION

It should certainly contain some relevant background data related to the problem,

then the statement of the problem should follow. It should contain a paragraph on what you hoped to achieve with the results of the study.

Note: Be selective, remembering that this section serves to justify your study, not to display your ability to read literature. IV. RESEARCH OBJECTIVES

The general and specific objectives should be included as stated in the proposal.

If necessary, you can adjust them slightly for style and sequence. However, you

should not change their basic nature.

If you have not been able to meet some of the objectives, this should be stated in

the methodology section and in the discussion of the findings.

V. METHODOLOGY

The methodology you followed for the collection of your data should be described

in detail.

The methodology section should include a description of:

the study type

major study variables on which data was collected

the study population, sampling method and the size of the sample

data-collection techniques used

how the data was collected and by whom

procedures used for data analysis, including statistical tests (if

applicable)

Methodological limitations: If you have deviated from the original study

design presented in your research proposal, you should explain to what extent you did so and why. The consequences of this deviation for meeting certain

objectives of your study should be indicated under the heading ‗limitations of the study‘.

VI. RESEARCH RESULTS (FINDINGS)

- The systematic presentation of your findings in relation to the research

objectives is the crucial part of your report.

- A description of the findings may be complemented by a limited number of tables or graphs that summarize the findings.



VII. DISCUSSION

- The findings can now be discussed by objective or by cluster of related

variables.

- The discussion may include findings from other related studies that support or contradict your own.

- It is important to present and discuss the limitations of the study.

- Some general conclusions may be included as well.

VIII. CONCLUSIONS

- The conclusions should follow logically from the discussion of the findings.

- As the discussion will follow the sequence in which the findings have been presented (which in turn depends on your objectives) the conclusions should logically follow the same order.

IX. RECOMMENDATIONS

- The recommendations should follow logically from the discussion of the findings.

- Recommendations may be summarized according to the groups towards which they are directed, for example:

policy-makers

health and health-related managers at different levels

health and health-related staff who could implement the activities

potential clients

the community at large

- Remember that action-oriented groups are the most important in this section.

- In making recommendations, use not only the findings of your study, but also supportive information from other sources.

X. REFERENCES

- References should be written in 'Vancouver style'.

- Citing References

1. Number references consecutively throughout the body of the

text in the order in which they are first mentioned. 2. DO NOT include references in your abstract. Identify references

in text, tables and legends by numerals in parenthesis e.g. (1), (2,3) or (3-6).



3. Some journals require references to be indicated in superscript which makes typing more difficult.

4. DO NOT use abstracts as your source of information, you must consult the full text of the article before using it as a cited

reference. 5. When citing authors in the text, acknowledge only the first

author where there are three or more authors, e.g. Williams et

al.(1994) stated that .....(1). Where there are two authors cite both, e.g. Jones and Smith (1997) reported that ....(2). Note that

a reference at the end of a sentence is included before the period.

6. The list of references must begin on a new page and they are

cited by number and sequenced by order of citation. Include all authors in the list of references.

How to format various reference sources? Journals

Harrison KL, Forster TH. Instruction to authors. Aust J Med Sci 1996; 17: 45-47. Author(s) of a book

Murray-Smith S. Right Words: A guide to English usage in Australia. 2nd ed. Melbourne: Penguin Books; 1990.

Author(s) of a chapter in a book

Bogduk N. Spinal pain: backache and neck pain. In: Gandevia SC, Burke D, Anthony M, editors. Science and practice in clinical neurology. Melbourne:

Cambridge University Press; 1993; 39-57. Internet referencing:

1. Document/Individual Work

Tyner R. Sink or Swim: Internet search tools and techniques (version 3) [WWW document]. Okanagan University College, 7 July 1998.

http://oksw01.okanagan.bc.ca/libr/connect96/search.htm [accessed 19 July 1998]. 2. Journals

Zorn P, Emanoil M, Marshall L, Panek M. Advanced searching: Tricks of the trade. Online [WWW]. 1996 May; 9 pages.

http://www.onlineinc.com/onlinemag/MayOL/zorn5.html [accessed 19 July 1998].

XI. ANNEXES OR APPENDICES

- The annexes should contain any additional information needed to enable

professionals to follow your research procedures and data analysis. - Examples of information that can be presented in annexes are:

Tables referred to in the text but not included in order to keep the

report short.

Interview schedule/ questionnaires (and/or other data collection

tools).



Making a scientific presentation Introduction

The quality of presentations in scientific meetings often leaves much

to be desired.

A number of sources are now available to help researchers improve

their presentations. Some are listed under the references and additional sources for this chapter. A good scientific presentation must follow the following three ―Ps‖. It should be: Planned with care,

Prepared with care and Presented with care. The following sections provide some useful guidelines, particularly for beginners.

Planning of the presentation

In planning a scientific presentation, presenters need to ask the organizers of the scientific meeting about: the audience and their

level of knowledge and interest in the subject since the planning of the presentation will be different for a specialist audience, a

generalist audience or a mixed audience; the time available for the presentation; and the type of visual aids available. Presenters should ask themselves what the main message (or messages) is that they

would like to convey and how it can be conveyed to the type of audience concerned in the time allotted.

The manuscript of an article (as submitted for publication) should not be used as such for a scientific presentation. The difference between speaking and writing is the same as the difference between hearing

and reading. A reader chooses his own pace; the listener must accept the pace chosen

by the speaker. Listening to the news on television is different from reading the

news in a newspaper. To change a written scientific paper into an oral presentation, the presenter must

follow three ―s words‖: Select, Synthesize, and Simplify. Select from the written article the points to present. Synthesize the information in the article to package it in the limited time available. Simplify the presentation of the data, so that it can be

easily followed and understood by the audience In the planning stage, the title of the presentation has to be decided and an abstract has to be submitted to the

organizers of the scientific meeting. A good title can be defined as the fewest possible words that adequately describe the contents of the presentation.



The abstract can attract or put off the audience. The abstract is the part

of the presentation that will be published in the conference programme. A good abstract should be a miniature version of the presentation. The abstract should be

sent to organizers before the deadline and in the format and length requested

Preparation Preparation of text In preparing the text of a scientific presentation: • Avoid too much detail and resist the temptation to overload the presentation with information.

• Avoid jargon and abbreviations, unless they are clear to all the audience. • Aim at the average person in the audience.

• Use plain English. The structure of a presentation is different from the structure of a written paper.

Normally, it should consist of three parts: introduction, main message and conclusions.

The introduction should tell the audience what the presentation will be about. Where possible, the opening sentences should capture the attention of the

audience. It helps to have something like a ―punch line‖, which will alert the audience to the importance of the subject. The main message should be clear and

concise. The usual detail of a written paper is unsuitable for a presentation. It is generally unwise to introduce more than one new idea every 2 to 3 minutes. The conclusion should summarize the main points. Try for a strong finish. Stopping

speaking is not finishing. Leave the audience with a ―take home message‖.

Preparation of visual aids: speaking visually Objectives for using visual aids It has been said that we

remember 20% of what we hear, 30% of what we see, but between 50% and 75% of what we see and hear (Sorgi and Hawkins, 1985). A Chinese proverb says ―A picture is worth a thousand words‖. Visual aids are not an

objective in themselves. They are used to serve one or more of the following objectives:

• holding the attention of the audience • presenting the data in a clear way • delivering the presentation without having to read from notes.

Commonly used visual aids include slides, overhead transparencies and comp uter

assisted presentations.



Slides Slides are the commonest visual aid used in scientific presentations. They

can make or break the presentation. Until recently photographic film slides were very commonly used; now electronic slides presented as a data show have largely

taken over. The basic rules for a good presentation are the same for film slides and electronic slides. There are three main types of slide: text slides, data slides (tables, graphs, flow charts) and figure slides. A mix of text, data and figure slides

helps to maintain the interest of the audience.

Text slides are not meant to be read by the speaker, but by the audience.

Lettering should generally be limited to 4 lines and should never be more than 7, including the title. It is advisable not to use more than 8 words per line.

Complicated tables are not visual aids. They have been described

as instruments of torture for the audience. Tables of data suitable for written publication are highly unsuitable for a scientific presentation. The term ―Railway

Timetable slides‖ is sometimes used to describe the difficulty with slides showing complicated tables. Do not use more than seven lines (including title) and four

columns in any table. The writing on a film slide should be easily legible by the naked eye. Use the whole area of the slide. There is no need to put the data in an outer box. Note in the design of the table that the transparent area in a film slide is

not square but oblong. Columns are preferably separated by a space larger than the width of the column.

Graphs should replace tables where possible in a visual presentation. They

are better in showing relationships. Preparation of graphs has now been made easy by computer programs. Four types of graphs are often used: bar or column

charts; curves; pie-charts; and scatter graphs.

•Bar charts are better for lettering than column charts. Avoid overcrowding the

slide. The number of bars should be limited to five to seven. An overcrowded column chart is sometimes called a ―New York Skyline‖ slide, to emphasize that it is not

suitable for presentation.

• No more than two or three curves can be shown on a slide. Space on the slide

should not be wasted. • The slices of a pie-chart must not be too numerous nor too small. Three to five

divisions are ideal. • Scatter graphs are good for slide presentation. They give a clear and simple overview of the scatter of the data to show relationship. Flow charts should not be



complicated. A complicated flow chart looking like a ―subway‖ map is not useful for a presentation.

A complicated flow chart can be built up in a number of successive slides. Figure slides of drawings and pictures, if meant for humour, should be selected

with care and sensitivity to the type of audience. They should not offend the feelings of anyone in the audience.

Tips in slide preparation A common mistake is to try to put too much on one slide. As a general rule, no slide should be shown unless it can be read by the back row of the audience. As a general rule, lettering on a film slide should be large enough to be read by the

naked eye without projection.

• The shape of a fi lm slide is rectangular: 36 × 24 mm. The dimensions of the

material on the slide should be prepared with this in mind. • Upper case letters are less legible than lower case letters. This is why lower case

is commonly used in direction signs on motorways and on the underground. Our eyes are more accustomed to small letters in books and newspapers.

• While choice of color is a matter of taste and judgment to a certain extent, color should not be used for decoration but to improve understanding. Select colors that project well. Popular combinations are blue and white, and green and yellow. Red

text may be more difficult to read. The number of colours should be limited to what is really necessary for presenting the data in a clear way.

Presentation The challenge to the speaker is to hold the attention of the audience. Particularly

when the lights are dim, the audience can have sweet dreams during a boring presentation

Get ready

Speak well

Manage your slides

Keep to the time

Be prepared to answer questions



Evidence Based Medicine

III. Evidence-Based Medicine (EBM)

2.1.2 Learning objectives:

By the end of this session, students will be able to:

1. Define EBM.

2. Explain the concept of EBM.

3. Explain why do we need (importance of) EBM in clinical practice.

4. Identify the five steps in the EBM Process.

5. Identify the parts of a well-built clinical question.

6. Construct a well-formed clinical questions using PICO method.

7. List the most common types of questions related to clinical tasks.

8. Determine the types of studies that give the best evidence for different

types of questions

9. Rank the level of evidence provided by different study designs.

10. Identify EBM resources and websites for searching relevant information.

Definition. Evidence-

based medicine has

been defined as "the conscientious, explicit,

and judicious use of current best evidence in making decisions about

the care of the individual patient.



Concept of EBM

EBM is the integration of clinical expertise, patient values, and the best research evidence into the decision making process for patient care. Clinical expertise refers to the clinician's cumulated experience, knowledge and

clinical ski lls. The patient brings to the encounter his or her own personal and unique concerns, expectations, and values. The best evidence is usually found in

clinically relevant research that has been conducted using sound methodology. Evidence-Based Practice requires new ski lls of the clinician, including efficient literature searching, and the application of formal rules of evidence in evaluating

the clinical literature.

Why do we need EBM?

- Medical knowledge is expanding at such a pace that makes it difficult for

medical practitioners to keep up with reading all the scientific literature and other up-to-date valid medical information.

- The inadequacy of traditional sources for medical information because they

are out-of-date (textbooks), sometimes wrong (expert opinions), ineffective

(didactic continuing medical education), or too overwhelming in their volume, and too variable in their validity for practical clinical use (medical journals).

- There is a large gap between what we know from research and what we do

in clinical practice.

- Much research is published — some valid and some invalid — clinicians are

unaware of most of it, or do not have the ‗tools‘ to assess its quality.

- Researchers, on the other hand, may not understand the information needs

of clinicians, and often present their work in a way that is not easily accessible to busy practitioners.

- Every day, doctors encounter questions that need to be answered in order to make the best decisions about patient care.

- Thus, introducing general practitioners and other health care professionals

to the concept of EBM will help them to avoid ‗information overload‘ but, at the same time, find and apply the most useful information on which health

care decisions are based.

Clinicians are required to:

1. Keep updated with current best evidence. 2. Learn to access, select, appraise and utilize up-to-date medical

information. 3. Skillful navigation of useful internet sites and use of appropriate search

engines for locating current best evidence

The Steps in the EBM Process



There are five steps to be considered in EBM process: 1. Asking an answerable clinical question.

2. Searching for the best evidence. 3. Critically appraising (evaluating) the evidence.

4. Applying the evidence to individual patient care, and 5. Evaluating the process.

clinical question 1: Formulate an answerable Step

- Start with the patient: a clinical problem/question arises during the patient encounter.

- Construct a well built clinical question using PICO method:

PICO is a method that helps one remember the key components of a well

focused question. The question needs to identify the key problem of the patient, what treatment you are considering for the patient, what alternative

treatment is being considered (if any) and what is the outcome you want to avoid or promote. Parts of a well-built clinical question:

a. Population/Patients

b. Intervention c. Comparison d. Outcome

Patient/ Population

Intervention/ Exposure

Comparison

Outcome Type of Question

In patients with acute myocardial

infarction (MI)

does early treatment with a

(a drug statin

used to lower cholesterol levels)

none decrease cardio- vascular

mortality

Therapy

In women with suspected

coronary artery disease (CAD)

what is the accuracy of

exercise ECHO

compared to exercise

ECG

for diagnosing significant

CAD?

Diagnosis

Types of Questions:

The most common types of questions related to clinical tasks are:

1. How to treat a disease or condition? How to select treatments to offer patients that do more good than harm and that are worth the efforts and costs of using them? INTERVENTION (THERAPY)

2. Does this person have the problem? How to select and interpret diagnostic tests? DIAGNOSIS

3. What causes the problem? AETIOLOGY AND RISK FACTORS



4. How to estimate the patient's likely clinical course over time and anticipate likely complications of disease? PROGNOSIS AND

PREDICTION

Types of Studies in Medical Literature:

Primary (Original research)

Experimental:

- Randomized controlled clinical trials (RCCT)

Observational:

- cohort studies - case-control studies

- Cross-sectional studies - Case series - case reports

Secondary

Reviews of original research

Practice guidelines

Types of study designs suitable for each clinical question

Type of clinical question

Suggested best type of Study

Therapy

RCT

Diagnosis

Cross-sectional, blind comparison to

a gold standard Etiology/Harm

RCT > cohort > case control > case series

Prognosis Cohort study > case control > case

series Prevention RCT > cohort study > case control >

case series

The Hierarchy of Study Design and Levels of Evidence

This pyramid serves as a guideline to the hierarchy of study design. You may not always

find the highest level of study to answer your question. In the absence of the best evidence,

you then need to consider moving down the pyramid. Step 2: Searching for the best evidence

Select the appropriate resource(s) and conduct a search. EBM Resources:



The following is a list of some valuable resources for practicing EBM.

Databases

PubMed | Cochrane Library | Center for Reviews & Dissemination

Summaries of the primary evidence

ACP Journal Club | Clinical Evidence | Dynamed | eMedicine | Essential Evidence Plus | FPIN Clinical Inquiries | UpToDate

Electronic textbooks and libraries AccessMedicine | ACPMedicine | ACP PIER | Stat!Ref | First Consult MDConsult EBM Websites:

JAMA Evidence: Fundamental tools for understanding and applying the

medical literature and making clinical diagnoses: http://www.jamaevidence.com

NC Evidence-Based Medicine Education Center of Excellence:

http://library.ncahec.net/ebm/pages/index.htm

Duke University Medical Center Library: Evidence-Based Medicine (EBM):

http://www.mclibrary.duke.edu/subject/ebm

Lamar Soutter Library, UMass Medical School, Worcester, MA Evidence-

Based Medicine Tutorials: http://library.umassmed.edu/EBM/tutorials/index.cfm

University of Illinois at Chicago, Evidence Based Medicine: Finding the Best Clinical Literature: http://www.uic.edu/depts/lib/lhsp/resources/ebm.shtml

Centre for Evidence-Based Medicine http://www.cebm.net/

Step 3: Appraise (Evaluate) the evidence

Appraise that evidence for its validity (closeness to the truth) and applicability (usefulness in clinical practice). We have now identified current information which can answer our clinical question.

The next step is to read the article and evaluate the study. Key issues that help determine the validity of study: There are three basic

questions that need to be answered for every type of study:

1. Are the results of the study valid?

2. What are the results? 3. Will the results help in caring for my patient? Are the results fulfilling the

patient's preferences?

(Refer to your EBM tutorial class)

Step 4: Apply the evidence

Return to the patient :



- What are your patient values and preferences? Is the evidence ( research provide an outcome that is similar to your patients' preferences?

- Integrate that evidence with clinical expertise, patient preferences and apply it to practice.

Step 5: Evaluate your performance with this patient Practice exercise:

Mr. X is 60 year-old presenting with 1 hour retrosternal chest pain. ECG shows lateral ST-elevation consistent with AMI. The physician is confused about the role of aspirin in this case.

1. Formulate PICO question.

2. What is the type of this clinical question? 3. What is the best study design to answer this question?



Note………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………



………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………



………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………



………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………



……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..