Comparing Hospitals

To the Editor: Chen et al. (Jan. 28 issue) 1 found that mortality rates for patients with myocardial infarction were lower at top-ranked hospitals than at others. Although the study was well done, it is premature to conclude that hospital rankings by commercial magazines are valuable. This conclusion depends on three assumptions that must be validated. The first assumption is that the risk-adjustment procedure was adequate. Even good risk-adjustment procedures may not take into account systematic differences in risk among hospitals. Possible sources of systematic differences include variations in the following factors: the response time of paramedical services and the technology . . .