To the Editor.
—Dr Katz and colleagues1 compare the actual disposition of patients with a diagnosis of unstable angina in emergency departments (EDs) with recommendations based on a national guideline from the Agency for Health Care Policy and Research (AHCPR). This work is significant because guidelines potentially influence both quality of care and utilization of scarce resources. Furthermore, the pressure to adopt guidelines is increasing as managed care proliferates.However, we would temper the authors' conclusion that adoption of the guideline is unlikely to achieve significant reductions in hospitalization. First, the definition of the cohort of patients in the study by Katz et al is likely to underestimate the number of low-risk patients and, thus, the extent of potential reductions. Katz et al did not explicitly distinguish between 2 groups of patients: those identified with unstable angina, who are at low risk for acute myocardial infarction (MI), vs those