Determinants of cardiac catheterization use in older Medicare patients with acute myocardial infarction.

BACKGROUND Cardiac catheterization is substantially underused among higher-risk patients with acute myocardial infarction (AMI) with appropriate indications but overused among patients with inappropriate indications. We sought to determine the importance of anticipated benefit and anticipated harm on the use of cardiac catheterization among older patients with AMI. METHODS AND RESULTS We performed an analysis of Medicare fee-for-service beneficiaries hospitalized with an AMI between 1998 and 2001. Multivariate models were developed to determine relative importance of anticipated benefit (baseline cardiovascular risk), anticipated harm (bleeding risk, comorbidities), and demographic factors (age, sex, race, regional invasive intensity) in predicting cardiac catheterization use within 60 days of AMI admission. Analyses were stratified by American College of Cardiology/American Heart Association class I or II as appropriate, and class III as inappropriate. Determinants of reduced likelihood of cardiac catheterization among 42 241 AMI patients with appropriate indications included (in order of importance) older age (likelihood chi(2)=1309.5), higher bleeding risk score (likelihood chi(2)=471.2), more comorbidities (likelihood chi(2)=276.6), female sex (likelihood chi(2)=162.9), hospitalization in low (likelihood chi(2)=67.9) or intermediate intensity invasive regions (likelihood chi(2)=22.4) (all P<0.001), and baseline cardiovascular risk (likelihood chi(2)=6.4, P=0.01). Among 2398 AMI patients with inappropriate indications, significant determinants of greater procedure likelihood included younger age, male sex, lower bleeding risk score, and fewer comorbidities. CONCLUSIONS Regardless of the procedure indication, the decision to perform cardiac catheterization in this population appears largely driven by demographic factors and potential harm rather than potential benefit of the procedure.