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Correlational Studies for Drug Effects. Alec Walker October 2014. Correlational Studies. Population frequency Population exposure Inference on association The problem of common cause. How we evaluate causal connections. Theory. Prediction. Data. Experiment.
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Correlational Studies for Drug Effects Alec Walker October 2014
Correlational Studies • Population frequency • Population exposure • Inference on association • The problem of common cause
How we evaluate causal connections Theory Prediction Data Experiment
Rheumatic Heart Disease at the House of the Good Samaritan, Boston, 1921-1920 MassellBF et al. N Engl J Med. 1988;318(5):280-6
Theories for Drug Safety • Case Reports • Correlations • Analogy • Animal Experience • Rumor
Clinical Course of Rheumatic Carditis Loss of Murmurs in rheumatic carditis patients in Boston • Case Fatality
A General Theory Penicillin availability Loss of Murmurs in rheumatic carditis patients in Boston • Case Fatality
A Broader Prediction Penicillin availability Loss of Murmurs in rheumatic carditis patients in Boston National declines in mortality from scarlet fever and its complications • Case Fatality
A Broader Prediction Penicillin availability Loss of Murmurs in rheumatic carditis patients in Boston National declines in mortality from scarlet fever and its complications • Case Fatality Examine rates
US Mortality from Strep and RF MassellBF et al. N Engl J Med. 1988;318(5):280-6
Correlational Studies • Pay attention to the unit of observation • Risk or rate is typically the metric • Does observation unit stand as a proxy for exposure? • Does observation unit stand as a proxy for other variable characteristics that predict outcome? • Yes Confounding (“ecological fallacy”) • No Instrument