Specialty of principal care physician and Medicare expenditures in patients with coronary artery disease: Impact of comorbidity and severity

Objective: To explore differences in expenditures for elderly patients with acute and chronic coronary artery disease according to the specialty of th e principal care physician. Study Design: Retrospective analysis of Medicare claims. Patients and Methods: A total of 250,514 patients with coronary artery dise ase (International Classification of Diseases, Ninth Revision, Clinical Mod ification [ICD-9-CM] codes 410-414) were drawn from a national random sampl e of 1992 Medicare expenditures. Patients were classified by the physician type with the highest number of Medicare Part B outpatient claims into a ca rdiologist group and a generalist group. The outcome was mean total expendi tures, stratifying (1) by comorbidity as measured by the modified Charlson Index and (2) by severity defined as the proportion of patients with acute myocardial infarction or unstable angina. Results: Those patients in the cardiologist group had lower comorbidity and higher severity than those in the generalist group. Overall mean expenditu res were significantly higher for the cardiologist group than for the gener alist group ($7658 vs $6047; P < .001). These differences in mean expenditu res were evident at each level of comorbidity. However, when stratified by severity of diagnosis, differences were seen predominantly in those with ac ute diagnoses. For those with either acute myocardial infarction or unstabl e angina, the mean expenditures were higher for the cardiologist group than for the combined generalist group ($15,378 vs $12,260; P<.001); however, t he mean expenditures for those with only chronic conditions were similar ($ 4856 vs $4745; P=.53). Conclusion: Expenditures were higher when cardiologists were the principal care physicians treating patients with acute disease but not chronic diseas e.