OBJECTIVE: To determine the impact of outpatient anticoagulant/antiplatelet therapy on treatment charges in patients receiving coronary artery stents in a managed care population. METHODS: Patients were selected from the PharMetrics Integrated Outcomes Database who underwent coronary angioplasty and stent insertion between January 1 and June 30, 1999 and who had at least 6 months of continuous enrollment in their health plan following the beginning of the treatment episode. Patients were grouped according to whether they received outpatient anticoagulant/antiplatelet prescription drug therapy following their stent procedure. Patients were also stratified by history of acute myocardial infarction (AMI) and presence of comorbid conditions (diabetes and hypertension). Total charges associated with the stenting treatment episode (up to 6 months following the procedure) were assessed. RESULTS: 2,713 patients receiving anticoagulant/antiplatelet therapy and 438 untreated patients met all selection criteria. The two treatment groups were similar in age (58.6 vs. 58.0 years respectively, p=0.322) and in the frequency of AMI (37.7% vs. 37.9% respectively, p=0.939) and of one or more comorbidities (73.3% vs. 71.5% respectively, p=0.427). Mean charges over the study period for the anticoagulant/antiplatelet cohort exceeded those in the untreated cohort by $4,748 (p=0.014). Pharmacy charges accounted for only $297 of this excess ($660 vs. $363, respectively). Most of the difference between treatment groups was in the medical costs of interventional cardiology. CONCLUSION: Among coronary stent recipients, the mean charge for a 6-month period in patients who also received anticoagulant/antiplatelet prescription drug therapy was 14% higher than in the untreated cohort, due mainly to higher medical charges. It is possible that untreated patients were less severely ill or had a favorable risk profile. Further investigation of these data will examine this issue.