THE HISTORY AND SCOPE OF EPIDEMIOLOGY

 

INTRODUCTION

-      epidemiologic research methods are a powerful tool for studying health.  Several issues that are typical of epidemiologic research studies are:

·        When there is a linkage or association between a factor and a health outcome, does this observation mean that the factor is a cause of disease?

·        If there is an association, does the amount of disease vary according to the amount of exposure to the factor?

·        Based on the observation of such an association, what practical steps should individuals and public health departments take?

·        Do the findings from an epidemiologic study merit panic or a measured response?

·        How applicable are the findings to settings other than the one in which the research was conducted?

 

-      epidemiology – a discipline that describes, quantifies, and postulates causal mechanisms for health phenomena in populations

 

EPIDEMIOLOGY DEFINED

-         from the word epidemic; from the Greek words epi (upon), demos (people); and logy (study of). 

-         concerned with the distribution and determinants of health and diseases, morbidity, injuries, disability, and mortality in populations.  The key aspects of this definition are determinants, distribution, population, and health phenomena (definition from text)

 

Determinants

-         factors or events that are capable of bringing about a change in health (physical inactivity)

 

Distribution

-         frequency of disease among population subgroups

 

Population

-         “population medicine” because its principles examine specific populations rather than individuals

 

Health Phenomena

-         investigate the state of health of chronic or infectious diseases – disability, injury, limitation of activity or mortality

 

Morbidity and Mortality

-         morbidity – illness, mortality – death

 

 

Aims and Levels

-         epidemiology is concerned with

·        describing the health status of populations by enumerating the cases of disease, obtaining relative frequencies of the disease within subgroups, and discovering important trends in the occurrence of disease

·        explaining etiology of disease by discovering causal factors as well as discovering modes of transmission

·        predicting occurrence of disease by estimating actual number of cases that will develop as well as to identify the distribution within populations (interventions and health care resources)

·        controlling the distribution of disease

 

FOUNDATIONS OF EPIDEMIOLOGY

Epidemiology is Interdisciplinary

-         draws from biostatistics; social, behavioral and medical sciences

-         why?, it is hard to explain diseases (chronic or acute) in an epidemiological manner through any one discipline

 

Methods and Procedures

-         population research – empirical; requires quantification (transfer to numbers)

-         often requires counting the number of cases of disease and examining their distribution according to demographic variables (age, sex, race, etc…)

 

Use of Special Vocabulary

-         frequency of disease occurrence – chapters 3 and 4 (morbidity and mortality; person, place and time)

-         study designs – chapters 6 and 7

 

Methods for Ascertainment of Epidemic Frequency of Disease

-         surveillance data collected on a continuous basis to determine if an epidemic has occurred

 

HISTORICAL ANTECEDENTS OF EPIDEMIOLOGY

 

 

RECENT APPLICATIONS OF EPIDEMIOLOGY

-         use of epidemiology has exploded in the last twenty years

-         on an almost daily basis, epidemiologic reports can be found in local or national newspapers

 

Infectious Diseases in the Community

-         infectious and communicable diseases – not relevant to this class

 

Health and the Environment

-         environmental exposure – not quite relevant, more so than infectious diseases

 

Chronic Disease, Lifestyle, and Health Promotion

-         Physical activity and CVD – very relevant

 

Psychologic and Social Factors in Health

-         Home environment, stress, staits, and traits of psychological health – fairly relevant

 

Molecular and Genetic Epidemiology

-         Genetic component of obesity is important; however, genetics is beyond the scope of this class

 

CONCLUSION

-         epidemiology is the study of distribution and determinants of disease

-         sometimes referred to as “population medicine”

-         quantification, special vocabulary and interdisciplinary approach