Pcv17 predictors of time to discontinue beta-blocker following acute myocardial infarction: an analysis of the medicare 5% national sample data 2006-2007

To study the predictors of beta-blocker therapy discontinuation among post myocardial infarction (MI) patients enrolled in Medicare. This is a retrospective cohort study utilizing a Medicare 5% national sample claims data for 2006-2007. Medicare beneficiaries with continuous Part A, B, and D enrollment in 2006=2007, and who were hospitalized for an acute MI in the first six months of 2006 were identified using a validated algorithm, requiring a hospitalization episode ≥3 and ≤180 days with an ICD-9-CM of 410.x1 as principal or secondary diagnosis. Post-MI patients with a filled prescription for beta-blocker within 90 days of discharge were followed until the end of the study period. Time to discontinuation was defined as days from initiation of therapy to a gap of >90 days in therapy. Survival curves were modeled using the Kaplan-Meier technique, and potential predictors of therapy discontinuation, including demographic characteristics, comorbid conditions and concomitant medications were estimated using Cox proportional hazards regression. Of the 2,505 subjects who met our inclusion criteria, 65.1% were females, 83.3% were Caucasian, mean age 78.6 (±8.2) years. About 15% of them discontinued therapy within six months and around 35% discontinued within a year. Males were more likely to discontinue therapy as compared to females (HR=1.166; [1.020-1.334]; p=0.0245) and Caucasians (HR=0.674; [0.557-0.815]; p<0.0001) were less likely to discontinue therapy compared to African Americans. The results of Cox proportional hazards model shows that diabetes (HR=1.224; [1.069-1.402]; p=0.0035), dyslipidemia (HR=0.675; [0.565-0.807]; p<.0001), CHF (HR=1.234; [1.03-1.478]; p=0.0223), cerebrovascular disease (HR=1.206; [1.057-1.376]; p=0.0054) and COPD (HR=1.209; [1.061-1.377]; p=0.0043) were significant predictors of time to discontinuation. Patients on concomitant statin treatment were less likely to discontinue beta-blocker therapy (HR=0.774; [0.667-0.899]; p=0.0008). Many patients initiating beta-blocker therapy post MI fail to consistently remain on the treatment. Several demographic characteristics and comorbid conditions are associated with this behavior.