Use of beta-blocker therapy in older patients after acute myocardial infarction in Ontario

Background: Despite its proven efficacy, beta-blocker therapy remains under used in elderly patients after myocardial infarction (MI). The objectives o f this study were to identify undertreated groups of seniors and to determi ne whether older and frailer patients are being selectively dispensed low-d ose beta-blocker therapy. Methods: From a comprehensive hospital discharge database, all people aged 66 years or more in Ontario who survived an acute MI between April 1993 and March 1995 were identified and classified into those who did not receive b eta-blocker therapy and those dispensed low, standard or high doses of this agent. Logistic regression models were used to study the effect of age, se x, comorbidity, potential contraindications to beta-blocker therapy and res idence in a long-term-care facility on the odds of not being dispensed a be ta-blocker. Among beta-blocker users, the odds of being dispensed low relat ive to standard or high doses of this agent were evaluated. Results: Of the 15 542 patients, 7549 (48.6%) were not dispensed a beta-blo cker. Patients 85 years of age or more were at greater risk of not receivin g beta-blocker therapy (adjusted odds ratio [OR] 2.8, 95% confidence interv al [CI] 2.5-3.2) than were those 66 to 74 years. Having a Charlson comorbid ity index of 3 or greater was associated with an increased risk of not rece iving beta-blocker therapy (adjusted OR 1.5, 95% CI 1.3-1.8) compared with having lower comorbidity scores. Patients who resided in a long-term-care f acility were at increased risk of not being prescribed beta-blocker therapy (adjusted OR 2.6, 95% CI 2.0-3.4). Among the 5453 patients with no identif iable contraindication to beta-blocker therapy, women were significantly le ss likely than men to receive this agent (p = 0.005). Of the 6074 patients who received beta-blockers, 2248 (37.0%) were dispensed low-dose therapy. P atients aged 85 years or more had an increased risk of being dispensed low- dose therapy (adjusted OR 1.6, 95% CI 1.3-2.0) compared with those aged 66 to 74 years. Compared with those who had the lowest comorbidity scores, pat ients with the highest comorbidity scores were more likely to be dispensed low-dose beta-blocker therapy (adjusted OR 1.3, 95% CI 1.0-1.8). Interpretation: Almost half of Ontario patients aged 66 or more who survive d an MI, particularly those who were older or frailer, did not receive beta -blocker therapy. Among those dispensed beta-blocker therapy, older and fra iler patients were more frequently dispensed low-dose therapy.