HLTB15 WINTER 2013
LECTURE # 10 – EPIDEMIOLOGY & STUDY DESIGNS
What is the DEFINTION of EPIDEMIOLOGY?
o The study of the distribution and determinants of health-related states in
specified populations and the application of this study to control health
What is the DEFINITION of DEMOGRAPHY?
o The scientific study of human populations, including their size, composition,
distribution, density, and growth as well as the causes and socio-economic
consequences of changes in these factors.
What the different TYPES of EPIDEMIOLOGY?
o CLINICAL - internally within the body
o SOCIAL - behaviourally
o CRITICAL – structurally, contextually
o COMMUNITY - happens in community
o OCCUPATIONAL – happens in the workplace
What are the TWO classes of EPIDEMIOLOGICAL STUDIES?
o EXPERIMENTAL – exposure is varied to detrmien how many get the
o OBSERVATIONAL – occurrence of disease is observed in people who are
What are the TWO main types of STUDY DESIGNS?
o DESCRIPTIVE – disease and related factors are measure, used when
health problem is suspected and you want to develop hypotheses
What are the TYPES of DESCRIPTIVE STUDY DESIGNS? Describe them!
o CORRELATIONAL STUDIES: Correlational studies, data from entire
population is used, cannot link exposure to diease in the same person
o CASE REPORTS: profile of a single person
o CASE SERIES: describes the characteristics of a number of patients
o CROSS SECTIONAL STUDY – exposure and disease measured at one one
point in time, survey population of interest, temporal association
cannot be clearly determined
What are the TYPES of ANALYTICAL STUDY DESIGNS?
o PROSPECTIVE COHORT – idnividuals are grouped based on exposure
status and follow up to determine if exposure increases, decreases or
has no effect on the development of disease
We do it when there is STRONG suggestion of ASSOCIATION,
exposure is RARE, and there is a SHORT average time between
EXPOSURE and DISEASE
Advantages: Expensive, Time Consuming, Loss to Follow Up,
Limited to Rare Opportunities, Ascertainment of Disease HLTB15 WINTER 2013
Advantages: Classification before the disease develops,
Calculation of incidence rates among exposed and not exposed,
Calculate risk directly,