Dr Eva Batistatou. Outline of this presentation… What is epidemiology? The Fundamentals of Epidemiology course What is biostatistics? The Biostatistics.

Fundamentals of Epidemiology

&Biostatistics

Dr Eva Batistatou

Outline of this presentation…

What is epidemiology?

The Fundamentals of Epidemiology course

What is biostatistics?

The Biostatistics course

What is Epidemiology?

Origin of the term:

epi (upon) + demos (people) + logy (study of)

What is Epidemiology?

Definition:

e.g.

‘The study of the distribution and determinants of disease frequency in man’

MacMahon & Pugh (1970)

One of the pioneers of epidemiology due to his study of cholera in London in 1854.

John Snow

(1813-1858)

Importance of Epidemiology in Public Health

Epidemiology provides the basis for describing and explaining disease occurrence in a community

Examples of epidemiological questions:

How many new cases of AIDS were reported among teenagers in USA last year?

We might want to compare the number of reported cases to numbers in prior years to get a sense of whether AIDS is increasing or decreasing in this age group.

The number of reported new cases of AIDS is almost three times higher in young adults, 20-24years of age, compared to teenagers.

…seeking an explanation for the difference into behaviors/factors that differ between the age groups eg sexual activity, intravenous drug use.

Importance of Epidemiology in Public Health

Also…

Epidemiology provides a basis for developing, prioritizing, and evaluating public health programs

Examples of epidemiological questions:

What problems are present in the community?

What problems have the greatest public health impact?

Are adequate health services available and accessible?

Is a specific public health program successful?

Risk

The probability of disease developing in an individual in a specified time interval

Association

The relationship between an exposure or risk factor and an outcome

Bias and confounding

Systematic errors in the collection or interpretation of data that must be minimised

Causation

Establishing that the association between an exposure and an outcome is causal

Descriptive studies

Describe the distribution of disease in relation to person, place and time

Case-control studies

What is the likelihood of exposure in people with disease compared with people without disease?

Cohort studies

What is the likelihood of developing disease for people who are exposed compared with people who are not exposed?

Intervention studies

What is difference in outcome among people who received the intervention compared to people who did not?

On completion of the FOE unit you should be able to:

Calculate incidence and prevalence rates

Outline the advantages and disadvantages of descriptive studies, case-control studies, cohort studies and interventional studies

Calculate the appropriate effect measures within these study designs such as the OR and the RR

Understand the types of bias that can occur in observational studies

Understand the impact that bias, confounding and effect modification can have on observational studies

Perform direct and indirect age standardisation

Understand the principles of routine epidemiological surveillance and screening

What do we need to answer our epidemiological questions?

Data!!!

And then…what?

What is Biostatistics?

It is the science which deals with development and application of the most appropriate methods for the:

Collection of data

Presentation of the collected data

Analysis and interpretation of the results

Making decisions on the basis of analysis

Collection of data

Sources of data

Records Surveys Experiments

Types of data

Constant Variable

s

Types of Variables

Qualitativee.g. favourite colour

Quantitative

Discretee.g. shoe size

Contin.e.g. height

Presentation of the collected data

Presentation of the collected data

Manchester Children’s Growth and Vascular Health Study data

On completion of the Biostats unit you should be familiar with:

the concepts on which statistical methods are based

different types of data and different types of statistical tests

statistical analysis using a statistical package (e.g. Excel, StatsDirect, SPSS)

focus on understanding and interpreting the output from a statistical package

And also…

Descriptive statistics: mean, median, standard deviation, confidence intervals etc

Hypothesis tests: z-test, t-test, Mann-Whitney, chi-square etc

Sample size, correlation and simple linear regression

Multiple linear regression and logistic regression

Survival analysis

Assignments

Assignment 1

- Week 5 (30% of final mark)

Assignment 2

- Week 10 (70% of final mark)

Overall score0-40% Fail40-50% Diploma pass50-70% Masters pass70-100% Distinction pass

Recommended reading

Raj Bhopal (2002) Concepts of Epidemiology: an integrated introduction to the ideas, theories, principles and methods of epidemiology

Kirkwood and Sterne (2003) Essential Medical Statistics