Association of physician and hospital volume with use of aspirin and reperfusion therapy in acute myocardial infarction

BACKGROUND. The association between volume of patients treated and quality of care has important implications for patient referral policies and approaches to quality improvement. Most studies have focused on hospital volume alone and health outcomes. OBJECTIVES. The objective of this work was to examine the association of hospital and physician volume with use of aspirin and reperfusion therapy in the management of acute myocardial infarction (AMI) in eligible patients. METHODS. We reviewed charts of 2,215 patients treated at 35 Minnesota hospitals for AMI between October 1, 1992, and July 31, 1993, comparing use of aspirin and reperfusion therapy in eligible patients across different physician and hospital volume categories through multiple logistic regression. RESULTS. Aspirin use did not vary significantly with physician volume. Use of reperfusion therapy was reduced among the lowest-volume physicians only (adjusted OR, 0.38; 95% CI, 0.15-0.94). Compared with the highest volume hospitals (treating >200 patients), aspirin use among lower-volume hospitals was lower. This was statistically significant only in the hospitals treating <30 patients (adjusted OR, 0.54; 95% CI, 0.30-0.97). These same hospitals had increased odds of using thrombolytics (adjusted OR, 3.02; 95% CI, 1,40-6.53). CONCLUSIONS. Differences in use of aspirin and reperfusion therapy occur at the extremes of hospital and physician volume. These observed differences are in the anticipated direction, except for the increased use of thrombolytics at very-low-volume hospitals. This may be a "desperation reaction" with a perceived lack of other alternatives, such as cardiac catheterization labs and cardiologists.