Introduction to EpidemiologyEHS 6655Dr. Feito

Epidemiology

Basic science of public health: A quantitative basic science built on a working knowledge of

probability, statistics, and sound research methods; A method of causal reasoning based on developing and testing

hypotheses pertaining to occurrence and prevention of morbidity and mortality;

A tool for public health action to promote and protect the public’s health based on science, causal reasoning, and a dose of practical common sense.

Applied epidemiology

Use to describe the application or practice of epidemiology to address public health issues: Examples:

Monitoring of reports of communicable disease Weather a dietary component influences risk of developing a

disease Effectiveness and impact of cholesterol awareness program Analysis of historical trends and current data to protect public

health resources

Say what??

In short!

“Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.”

Definition Broken down

Study- “basic science of public health.”Distribution- concerned with the frequency and

pattern of health events in a population. Frequency- includes the number & rate or risk of Dz. Pattern- events by time, place & personal characteristics.

Determinants- causes & factors that influence the occurrence of a Dz (why & how). Health-related states or events- “diseases”

Definition Broken down, con’t

Specified populations- Clinicians = health of individual Epidemiologist = collective health of people

Application- data for directing public health action.

Uses

Population or community health assessmentIndividual decisionsCompleting the clinical pictureSearch for causes

Can we “prove” it?

Goals

Describe distribution of disease who gets the disease and where and when it occurs.

Analyze descriptive information identify risk factors associated with the probability of disease

occurrence.

Prevent disease occurrence modifying identified risk factors.

Evolution of Epidemiology

Early Thinkers

• Hippocrates (circa 400 B.C.)– Attempted to explain disease occurrence from

a rational instead of a supernatural viewpoint.– “On Airs, Waters, and Places”

• Suggested that environmental and host factors (e.g. behaviors) might influence the development of disease.

“…all parts of the body which have a function, if used in moderation and exercised in labours in which each is accustomed, become thereby healthy, well-developed and age more slowly, but if unused and left idle they become liable to disease, defective in growth and age quickly.” ~ c. 450 B.C.

Early Thinkers

John Graunt (1620 – 1674) Published analysis of mortality data in

1662. First to quantify patterns of birth, death,

and Dz occurrence, noting male-female disparities, high infant mortality, urban-rural differences, and seasonal variations (life tables)

Early Thinkers

William Farr (1807 – 1883) Founder of modern vital stats

& surveillance, developed basic principles used today.

Used John Graunt’s work to systematically collect and analyze Britain’s mortality statistics.

John Snow

“Father of Epidemiology”Studied cholera outbreaks

Discover the cause Prevent its recurrence

Work illustrates:

Physical Activity Epidemiology

Physical Activity Epidemiology

Studies factors associated with participation in Physical activity and how this behavior relates to the chance of disease or injury. Description of PA levels in a population Comparing levels of PA among populations Factors associated with PA Association between PA and risk of chronic diseases

Pioneers

Jerry Morris (UK; 1910 – 2009) After WWII CHD were in the rise Hypothesized:

“Deaths from CHD would be less common among physically active men at work than among those in sedentary jobs.” (1953)

Ralph S. Paffenbarger, Jr. (US; 1922 – 2007) Harvard Alumni Study