Improved observational method for studying therapeutic efficacy. Suggestive evidence that lidocaine prophylaxis prevents death in acute myocardial infarction
R. I. Horwitz and A. R. Feinstein
Criteria for patient eligibility in a randomized clinical trial can be used
to improve the design of observational case-control studies. The new
strategy has been illustrated in a case-control investigation of whether
lidocaine prophylaxis prevents death in patients with acute myocardial
infarction. From among patients hospitalized with myocardial infarction in
a special care unit during 1974 to 1978, there were 151 fatalities (cases)
and 151 survivors (controls) selected for study. After removal of the
ineligible cases and controls, lidocaine prophylaxis was found to have no
effect on death from pump failure or nonarrhythmic causes, but was
significantly protective against death from ventricular arrhythmias,
particularly in patients with congestive heart failure. If confirmed by
rigorously designed longitudinal studies, the improved case-control
technique could serve as a useful "screening' device to assess the efficacy
of medical or surgical treatments that cannot be tested with randomized
clinical trials.
