Arun epidemio

SEMINAR ON EPIDEMIOLOGICAL METHODS

"I keep six honest serving men;they taught me all I know Their names are what, why , when, how , where, and who"

ETYMOLOGY

The term “epidemiology” is derived from three Greek words 'epi' means among or upon 'demos' meaning people and 'logos 'means study or knowledge.

DEFINITIONS

the branch of medical science dealing with epidemics (Parkin in 1873)

Epidemiolgy is the science of mass phenomena of infectious diseases. (FROST, 1927)

Epidemiology is the study of disease, any disease, as a mass phenomenon.

(GREENWOOD , 1934)

DEFINITIONS

The study of the distribution and determinants of disease frequency in man . (MacMahan , 1960)

Epidemiology is the study of various factors and conditions that determine the occurrence and distribution of health . disease, defect, disability , and death among groups of individuals.

(Clark, 1965)

DEFINITIONS

”the study of the distribution and determinants of health related states and events in specific populations and the application of the study of control health problems"

(John.M.Last 1988).

History Of Epidemiology

Epidemiology begins with Adam and Eve , both trying to investigate the qualities of the "forbidden fruit".

The first epidemiologist that emerged on the scene was Hippocrates himself.(460-447 BC).

History Of Epidemiology

The most outstanding epidemiological study in the nineteenth century was that conducted by john Snow on cholera in London in the year 1854 in which he established, beyond any doubt, that cholera is a water-borne disease.

History Of Epidemiology The application of epidemiology in nursing can

be traced back to Florence Nightingale, considered the issues related to the hospital statistics and diseases classification and took suggestions from William Farr, the chief statistician, General Registar Office,England. Florence Nightingale contributed to the development of epidemiology in her work with British soldiers during the Crimean War (1854 to 1856)

History Of Epidemiology

Recently, epidemiological studies were instrumental in exploring the natural history of AIDS,identifying modifiable risk factors associated with it and providing a framework for its control at a time when neither a vaccine nor an effective treatment is available.

BASIC CONCEPTS IN EPIDEMIOLOGY

agent host environment

agent

hostenvironment

BASIC CONCEPTS IN EPIDEMIOLOGY Agent: an animate or inanimate factor that must

be present or lacking for a disease or condition to develop.

Host: a living species (human or animal) capable of being infected or affected by an agent.

Environment: all that is internal or external to a given host or agent and that is influenced and influences the host and/or agent.

Scope Of Epidemiology

Scope: Scope means opportunity for unhampered motion, activity , or thought, or extend of appications.

Scope Of Epidemiology

Epidemiology studies the determinants of health-related states and events.

Epidemiology studies the distribution of health-related states and events; the distribution is viewed in three epidemiological dimensions of time, place and person.

Scope Of Epidemiology

Epidemiology finds application in the control of health problems.

Modern epidemiology deals with measurements of occurrence of health related states or events which include diseases, disabilities, death, physiological conditions, health needs, health demands, health care utilization and health behaviors.

Scope Of Epidemiology

Evaluation of usefulness and effectiveness of new or innovative techniques.

Conducting epidemiological researches on changing trends in the distribution and determinants of health and illness.

AIMS OF EPIDEMIOLOGY

Aim: The word aim means to direct towards an intented target

AIMS OF EPIDEMIOLOGY

According to International Epidemiological Association(IEA), epidemiology has three main aims,

To describe the distribution and magnitude of health and disease problems in human populaions.

To identify the etiological factors or risk factors in the pathogenicity of disease.

To provide the data essential to the planning , implementation and evaluation of services.

USES OF EPIDEMIOLOGY

to study the occurrence of diseases in a population.

to study historically the rise and fall of disease in the population.

to identify health problems in a community. quantifying a health problems in the

community

USES OF EPIDEMIOLOGY

quantifying a health problems in the community

to diagnose the health of the community

Searching for cause and risk factors to identify determinants of disease

USES OF EPIDEMIOLOGY

to estimate individual risks and chances to plan health services to evaluate intervention measures to complete Natural History of Diseases. to identify syndrome. to forecast future disease trends.

Ultimate Aim Of Epidemiology

eliminate or reduce the health problem or its consequences

promote the health and well being of society as a whole.

METHODS OF EPIDEMIOLOGY

Method is defined as a mean or manner of procedure, especially a regular and systematic way of accomplishing something.

Classification Of Epidemiological Studies

1) Observational epidemiology Descriptive epidemiologyAnalytical epidemiology ecological studies cross-sectional studies case control studies cohort studies2)Experimental Or Investigative Epidemiology Randomized controlled trial Field trial Community trial

1) Observational epidemiology

The observational studies collect evidences based on the observations of routine records , reports, and routine happenings. Under observational epidemiology , an epidemiologists measures the incidence and prevalence of disease, death, defect or disability or any other event in the community or population and does not intervene. Observational epidemiology falls into descriptive epidemiology and analytical epidemiology.

Descriptive Epidemiology Descriptive epidemiology refers to the distribution of

disease, death, and other health outcomes in the population according to person, place, and time. This type of epidemiology provides a picture of how things are or have been the who, where, and when of disease patterns.

Descriptive studies are usually the first phase of an epidemiological investigation.

These studies are concerned with observing the distribution or disease, or health related characteristics in human .populations and identifying characteristics with which the disease seems to be associated

Procedures in descriptive Studies Defining the population to be studied Defining the disease under study Describing the disease by

Time place person

Measurement of disease . Comparing with known indices . Formulation of an etiological hypothesis .

Defining the population to be studied Criteria for defining a population The "defined population" can be the whole

population in a geographic area, or more often are representative sample taken from it. The defined population can also be a specially selected group such as age and sex groups, occupational groups, hospital patients, school children, small communities as well as wider groupings

Defining the population to be studied

The defined population needs to be large enough so that age, sex and other specific rates are meaningful.

The community chosen should be stable without migration into or out of the area.

It should be clear who does and who does not belong to the population as for example, visitors and relations.

The most essential ingredient is community participation.. Furthermore, the population should not be overtly different from other communities in the region.

Finally, a health facility should be close enough to provide relatively easy access for patients requiring medical services.

2. DEFINING THE DISEASE UNDER STUDY The , epidemiologist looks out for an

"operational definition", i.e..a definition by which the disease or condition can be identified and measured in the defined population with a degree of accuracy.

DESCRIBING THE DISEASE

The primary objective of descriptive epidemiology is to describe the occurrence and distribution of disease (or health- related events or characteristics within populations) by time, place and person .and identifying those characteristics associated with presence of absence of disease in individuals This involves' systematic collection and analysis of data. . It is only an initial separation or grouping of variables according to time, place and person

Time Distribution

Epidemic Trends 1.Short-term fluctuations The best known short-term fluctuation in the occurrence

of a disease is an epidemic. According to modern concepts an epidemic is defined as "the occurrence in a community or region of cases of an illness or other health - events clearly in excess a normal expectancy". The community or region, and the time period in which the cases occur, are specified precisely. Epidemicity is thus relative to usual frequency of the disease in the same area, among the specified population, at the same season of the year

Main features of a Point epidemicThe main features of a "point-source" epidemic

are: (i) the epidemic curve rises and falls rapidly,

with no secondary waves ii) the epidemic tends to be explosive, there is clustering of cases within a narrow interval of time, and

(iii) more importantly, all the cases develop within one incubation period of disease ..

EXPERIMENTAL EPIDEMIOLOGY

(a) Confirming cause—effect associations or judging the validity of hypotheses established by observational studies.

(b) Evaluating various treatment modalities and interventional procedures applicable in hospital situations.

(c) Evaluating the feasibility, efficacy and relevance of various preventive programmes of public health significance.

(d) Evaluating the feasibility, efficacy and relevance of various risk-intervention approaches of public health importance.

(f) to provide "scientific proof" of etiological (or risk) factors which may permit the modification or control of those diseases.

COHORT STUDY

Cohort study is another type of analytical (observational) study which is usually undertaken to obtain additional evidence to refute or support the existence of an association between suspected cause and disease. Cohort study is known by a variety of names : prospective study, longitudinal study, incidence study, and forward looking study.

EXPERIMENTAL EPIDEMIOLOGY

TYPES

There are three designs of experimental or intervention epidemiology:

· Randomized controlled trials • Field trials · Community trials.

Randomized Controlled Trials (Rct) The randomized controlled trials are also

known a randomized clinical trial.

Obiectlve Objective of RCT is to study the

effectiveness of a new drug or a regimen in ‘patients’

Randomized Controlled Trials (Rct) Steps1. First step in RCT is to prepare a plan of study or

protocol what you wish to test or study.2. Define study population.3. Selection of participants by defined criteria as

per plan.4. Randomization of participants.5. Treatment group and control group.

(intervention)6. Follow-up of these groups.7.Assessment of outcome(Analysis)

FIELD TRIALS

Field trials in contrast to clinical trials focus on healthy populations who are exposed to the risk of development of disease.

COMMUNITY TRIALS

ln these trials, the treatment groups are commununities rather than individuals

Common Errors In Epidemiological Methods

Random Errors Sampling errors

EPIDEMIOLOGY AND NURSES

Role of nurse as an epidemiologist Role : Roles refers to what is expected of

a nurse in any setting or situation.

which include

Role of nurse as an epidemiologist

Administration of general and specific health survey

Participation in early diagnosis and treatment

Identification And Notification of certain specific diseases

Health education

Role of nurse as an epidemiologist

Facilitation and Mentoring .Leader Researcher

SOME RECENT EVENTS

CONCLUSION