1 Introduction Biostatistics and Epidemiology

The Census

• They conducted this to find out how many people there are in the country.

• Every 5 years every Roman man had to register

• The men had to declare their family, wife, children, slaves, and riches.

• If a man didn’t do this his possessions would be confiscated; if a man wanted to free his slave he would only have to enter his name as a citizen

Census in Roman Empire

• The Romans wanted to know how many people belonged to their empire for taxation purposes.

• There was a decree from the Roman Government that people must go back to their original place.

2,500 years old

Epidemiology’s roots are nearly

Hippocrates

During the 400 B.C.

• He declared a viewpoint disease occurrence is not due to supernatural events. He believes it is caused by some microorganism or some substances that come from the environment.

• His essay Entitled “On Airs, Waters, and Places” suggested that Environmental and host factors such as behaviors might influence the development of disease.

John Graunt

Father of Demography. He took note of the different signs and symptoms of the disease and made a compilation of it. Book “Bills of Mortality” published in 1662

John Snow

Father of Epidemiology. The first one who had an impact on the count of diseases of an epidemic in London specifically “Cholera”.

1929, 1937, 1948

• In ____ a huge paper on application of statistics was published in Physiology Journal by Dunn.

• In ____, 15 articles on statistical methods by Austin Bradford Hill, were published in book form.

• In ____, a RCT (Randomized Control Trial) of Streptomycin for pulmonary TB., was published in which Bradford Hill had a key influence.

Randomized Control Trial

• This is the procedure used or done by epidemiologists when they have to make vaccines or produce medicines. The trial should be fully finished before they give the vaccine.

• The last phase of the trial is usually done through a mass trial - it is tried on many people and checked to see if it has bad effects.

1952, 1982

Then the growth of Statistics in Medicine from _____ was an 8-fold increase by ______.

Statistics

The science which deals with collection, classification, and tabulation of numerical facts as the basis for explanation, description, and comparison of the phenomenon”(Lovitt)

Biostatistics

• Statistics arising out of biological sciences, particularly of Medicine and Public Health.

• The methods used in dealing with statistics in the fields of medicine, biology and public health for planning, conducting and analyzing data which arise in investigations of these branches.

Purpose of Biostatistics

• Health Disciplines are becoming increasingly quantitative.

  • Statistics pervades the medical literature

• The planning, conduct and interpretation of much of health research are becoming increasingly reliant on statistical methodology.

Preventive Medicine

• To provide the magnitude of any health problem in the community.

• To find out the basic factors underlying ill-health.

• To evaluate the health programs which were introduced in the community (success/failure).

• To introduce and promote health legislation.

Clinical Medicine

• Documentation of medical history of diseases

• Planning and conduct of clinical studies

• Evaluating the merits of different procedures

• In providing methods for the definition of “normal” and “abnormal”

• Planning

• Design

• Execution (Data collection)

• Data Processing

• Data analysis

• Presentation

• Interpretation

• Publication

WHAT DOES STATISTICS COVER?

• Design of study

• Sample size & power calculations

• Selection of sample and controls

• Designing a questionnaire

• Data Management

• Choice of descriptive statistics & graphs

• Application of univariate and multivariate statistical analysis techniques

HOW A “BIOSTATISTICIAN” CAN HELP

Epidemiology

The study of the distribution and determinants of health-related states in specified populations, and the application of this study to control health problems

• upon

• people

• study

epi- ______, demi- ____, ology- ______

Frequency

• Number of health events

• Relationship of the number of events to the size of the population.

Example of Frequency

Example: Number of cases of diabetes in a population

Example of Frequency. Relationship of the number of events to the size of the population

• Example: The resulting rate allows the comparison of disease occurrence across different populations

Pattern

The occurrence of health-related events by time, place, and person.

• Time patterns

• Place patterns

• Personal Characteristics

Types of Patterns

Time patterns

Annual, seasonal, weekly, daily, hourly, weekday versus weekend, or any other breakdown of time that may influence disease or injury occurrence.

Place patterns

Geographic variation, urban/rural differences, and location of work sites or schools.

Personal Characteristics

Demographic factors - related to risk of illness, injury, or disability such as age, sex, marital status, and socioeconomic status, behaviors and environmental exposures.

Determinants

Causes and other factors that influence the occurrence of disease and other health-related events.

Examples of Determinants

Examples: Socio-demographic factors (age, sex, marital status), Socio-economic factors (family income), environmental factors, individual and family lifestyle, community, political scenario

Determinants

• Assess whether groups with different rates of disease differ in their demographic characteristics to provide sufficient evidence to direct prompt and effective public health control and prevention measures.

  • Examples : genetic or immunologic make-up, behaviors, environmental exposures, or other socalled potential risk factors

Social Determinants of Health (WHO)

Determinants of Health