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Presented at the Scientific Conference
of the Saudi Epidemiology Association on 24 November 2015, by Professor Omar
Hasan Kasule Sr. MB ChB (MUK). MPH (Harvard), DrPH (Harvard)
Epidemiology
is the study of the distribution and determinants of both disease and injury. Starting
as a study of epidemics, it extended to communicable infectious and later non-communicable
diseases. It has now become a methodological discipline that is applied even to
non-disease phenomena such as administration and decision making. Application
of the epidemiologic methodology to various disciplines has produced
sub-classifications such as communicable disease epidemiology, chronic disease
epidemiology, public-health epidemiology, clinical epidemiology, hospital
epidemiology, pharmaco-epidemiology, genetic epidemiology, molecular
epidemiology, occupational epidemiology, and environmental epidemiology. The epidemiological
methodology, following the scientific method, is empirical, inductive, and
refutative. Empiricism refers to reliance on physical proof. Induction is
building a theory from discrete observations. Refutation is rejection of a
supposition until empirical evidence proves otherwise.
Epidemiological
investigation is not as deterministic or as accurate as laboratory
investigation but is cheap, quick and easy. It has always suggested effective
disease preventive interventions even before the complete causal pathways were
worked out. It points the way to confirmatory laboratory investigation. An
epidemiologic investigation proceeds through identifying and describing a
problem, using the scientific method to formulate and test hypotheses, and
interpreting findings. Epidemiological information is sourced from existing
data (medical records) or studies (observational or experimental).
The case
control study is in my mind the most effective contribution of epidemiology to
modern disease investigation. The case-control study is popular because or its
low cost, rapid results, and flexibility. It uses a small numbers of subjects
and is used for both rare and common conditions. It is used for disease (rare
and non-rare) as well as non-disease situations. The 4 variants of case control
design (case-base, the case-cohort, the case-only, and the crossover) are widely
used.
Study
interpretation and communication of findings to the public pose problems. Risk
reports that are not yet confirmed are picked up by the media and create
unnecessary public concern. Study findings affect policy. Epidemiologists must
know how to communicate risk to the public. It is an ethical obligation to
report research findings to subjects so that they may take measures to lessen
risk. Epidemiological evidence is different from legal evidence.
Epidemiological evidence may not be accepted in a court of law because it has
few certainties; it is concerned with populations whereas legal evidence
pertains to individuals.