The article entitled "Does More Intensive Treatment of Acute Myocardial Infarction in the Elderly Reduce Mortality? Analysis Using Instrumental Variables" by McClellan et al1 in this issue of The Journal is important for several reasons. The authors describe a new method in medical outcomes research called instrumental variables estimation. In principle, this approach eliminates the bias of patient selection on mortality in the Medicare population receiving varying intensities of treatment for acute myocardial infarction, particularly cardiac catheterization and associated coronary revascularization. The authors argue that this approach has the same effect as prospective randomization in eliminating unrecognized biases of patient selection on outcomes of differing treatment intensities.
The article makes the following conclusions for the Medicare population: (1) after acute myocardial infarction, cardiac catheterization and associated revascularization are performed less frequently in women and black men than in white men; (2) cardiac catheterization and associated revascularization have a marginal
Gould KL. Invasive Procedures in Acute Myocardial InfarctionAre They Beneficial?. JAMA. 1994;272(11):891-893. doi:10.1001/jama.1994.03520110071033