Influence of physician specialty on adoption and relinquishment of calcium channel blockers and other treatments for myocardial infarction.

Objective: Recent reports have linked calcium channel blockers (CCBs) with an increased risk of acute myocardial infarction (AMI). We sought to determine to what extent physicians relinquished CCBs following these adverse reports and if there were differences in the use of CCBs and other AMI therapies across 3 levels of specialist involvement: generalist attendings, collaborative care (generalist with cardiologist consultation), and cardiologist attendings.
Design: We measured use of CCBs during hospitalization for AMI before (1992--1993) and after (1995--1996) the adverse CCB reports, controlling for hospital-, physician-, and patient-level variables. We also examined use of effective medications (aspirin, beta-blockers, thrombolytic therapy) and ineffective AMI treatments (lidocaine).
Setting: Thirty-seven community-based hospitals in Minnesota.
Patients: Population-based sample of 5,347 patients admitted with AMI.
Measurements: The primary outcome was prescription of a CCB at the time of discharge from hospital. Secondary outcomes included use of other effective and ineffective AMI therapies during hospitalization and at discharge.
Main Results: Compared with cardiologists, generalist attendings were less likely to use aspirin (37% vs 68%; adjusted odds ratio [OR], 0.58; 95% confidence interval [95% CI], 0.42 to 0.80) and thrombolytics (29% vs 64%; adjusted OR, 0.18; 95% CI, 0.13 to 0.25), but not beta-blockers (20% vs 46%; adjusted OR, 0.93; 95% CI, 0.66 to 1.31). From 1992--1993 to 1995--1996, the use of CCBs in patients with AMI decreased from 24% to 10%, the net result of physicians starting CCBs less often and discontinuing them more often. In multivariate models, the odds of CCB relinquishment after the adverse reports (adjusted OR, 0.33; 95% CI, 0.27 to 0.39) were independent of, and not modified by, the involvement of a cardiologist.
Conclusions: Compared with cardiologists, generalist physicians were less likely to adopt some effective AMI therapies, particularly those associated with risk such as thrombolytic therapy. However, generalists were as likely as cardiologists to relinquish CCBs after the adverse reports. This pattern of practice may be the generalist physicians' response to an expanding, but increasingly risky and uncertain, pharmacopoeia.