Does More Intensive Treatment of Acute Myocardial Infarction in the Elderly Reduce Mortality? Analysis Using Instrumental Variables

Comment: Increasingly, outcome analysis will be used to determine benefit or lack of benefit of cosdy treatment protocols, especially when minimal return as measured in prolongation of life is achieved only with use of limited resources. This approach has been hampered in the past by investigators' inability to compare study groups with unobservable characteristics. This report documents the validity of applying a statistical method called instrumental variables estimation in the analysis of outcome data in which some patient variables cannot be observed. The clinical conclusion of the study is that elderly patients living in rural areas do not receive the acuity of care, i.e., catheterization and revascularization, as often as their counterparts in urban areas. The effect on outcome is limited to the first day following acute myocardial infarction. The authors argue that a cost-effective balance might be achieved by shifting resources to rural areas, performing fewer catheterizations and revascularizations in the urban setting, and having greater availability of prehospital and intensive care in the rural setting.