Association And Causation

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Association And Causation DR.D.SHANKAR REDDY MD COMMUNITY MEDICINE:

Association And Causation DR.D.SHANKAR REDDY MD COMMUNITY MEDICINE

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Descriptive studies endeavors to suggest aetiological hypotheses. Analytical and Experimental studies test’s hypotheses. Association may be defined as the occurrence of two variables more than that would occur by chance alone.

Association:

Association Spurious association Indirect association Direct (Causal) association: i ) one to one causal association ii) multifactorial causation

Spurious Association:

Spurious Association Perinatal mortality Home 5174 births 5.4/1000 Hospital 11156 births 27.8/1000

Indirect Association:

Indirect Association Confounder eg : Iodine deficiency related to altitude and Endemic goitre . Sucrose and CHD Iodine deficiency Altitude Endemic Goitre

Direct( causal) Association:

Direct( causal) Association One to one: is complicated by one factor being responsible for more than one disease. Haemolytic streptococci causes strep. Sore throat, Scarlet fever, Erysipelas . Multifactorial : NCD CHD

Additional Criteria For Judging Causality (Bradford Hill):

Additional Criteria For Judging Causality (Bradford Hill) Temporal Association: Strength of Association : Dose response relationship: Replication of finding: Biologic plausibility: Consideration of alternate explanations: Cessation of exposure: Consistency with other knowledge: Specificity of the association:

Uses of Epidemiology:

Uses of Epidemiology Identifying the causes of disease Legionnaire’s disease Completing the clinical picture of disease Tuskegee experiment Determining effectiveness of therapeutic and preventive measures Mammograms, clinical trials Identifying new syndromes Varieties of hepatitis

Uses of Epidemiology:

Uses of Epidemiology Monitoring the health of a community, region, or nation Surveillance, accident reports Identifying risks in terms of probability statements DES daughters Studying trends over time to make predictions for the future Smoking and lung cancer. Estimating health services needs

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