Correlational Studies for Drug Effects

Alec Walker October 2014

1

Correlational Studies

Population frequency Population exposure Inference on association The problem of common cause

How we evaluate causal connections

3

Theory

Prediction

Experiment

Data

Rheumatic Heart Disease at the House of the Good Samaritan, Boston, 1921-1920

4

Massell BF et al. N Engl J Med. 1988;318(5):280-6

Theories for Drug Safety

Case Reports Correlations Analogy Animal Experience Rumor

Case Fatality

Clinical Course of Rheumatic Carditis

Loss of Murmurs

in rheumatic carditis patients in Boston

Case Fatality

A General Theory

Loss of Murmurs

in rheumatic carditis patients in Boston

Penicillin availability

Case Fatality

A Broader Prediction

Loss of Murmurs

in rheumatic carditis patients in Boston

Penicillin availability

National declines in

mortality from scarlet fever

and its complications

Case Fatality

A Broader Prediction

Loss of Murmurs

in rheumatic carditis patients in Boston

Penicillin availability

National declines in

mortality from scarlet fever

and its complications

Examine rates

US Mortality from Strep and RF

10

Massell BF 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

Suicide v. CCBs in Sweden

Thank You!