Principles of Epidemiology & Epidemiologic methods
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Introduction • Epidemiology began with Adam & Eve • Epi- Among, Demos- people, logos- study) • Foundation laid in 19th century.
Definition• “The study of the distribution & determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.” (John M. Last, 1988)• Three components: – Studies of disease frequency, – Studies of the distribution and – Studies of the determinants.
Disease frequency• Measurement of frequency of – Disease, disability, death• Summarizing these in terms of rates & ratios.• Essential for comparing with diff. population / subgroup of the same population.• May yield important clues to disease aetiology & development of strategies for disease prevention / control.
Distribution of Disease• Disease / health related matters not uniformly distributed in the populations.• It occurs in patterns in a community &, study of these patterns in terms of time, place & persons may lead to the hypotheses about risk / causative factors and leads to measures for control / prevention of the diseases.• This part of epidemiology “Descriptive epidemiology”
Determinants of diseases• Test etiological hypotheses and identify the underlying risk / causative factors of the disease.• Analytical epidemiology.• Help in development of health programs, interventions & policies.
Aims of Epidemiology• To describe the distribution & magnitude of health & disease problems in human populations.• To identify etiological factors / risk factors in the pathogenesis of disease• To provide the data essential to the planning, implementation & evaluation of services for the prevention, control and treatment of diseases and to the setting up of priorities among those services.