Factors associated with the use of evidence-based therapies after discharge among elderly patients with myocardial infarction

Background

In an accompanying article, we report moderate between-hospital variation in the postdischarge use of β-blockers, angiotensin-modifying drugs and statins by elderly patients who had been admitted to hospital with acute myocardial infarction. Our objective was to identify the characteristics of patients, physicians, hospitals and communities associated with differences in the use of these medications after discharge.

Methods

For this retrospective, population-based cohort study, we used linked administrative databases. We examined data for all patients aged 65 years or older who were discharged from hospital in 2005/06 with a diagnosis of myocardial infarction. We determined the effect of patient, physician, hospital and community characteristics on the rate of postdischarge medication use.

Results

Increasing patient age was associated with lower postdischarge use of medications. The odds ratios (ORs) for a 1-year increase in age were 0.98 (95% confidence interval [CI] 0.97–0.99) for β-blockers, 0.97 (95% CI 0.97–0.98) for angiotensin-converting-enzyme inhibitors and angiotensin-receptor blockers and 0.94 (95% CI 0.93–0.95) for statins. Having a general or family practitioner, a general internist or a physician of another specialty as the attending physician, relative to having a cardiologist, was associated with lower postdischarge use of β-blockers, angiotensin-modifying agents and statins (ORs ranging from 0.46 to 0.82). Having an attending physician with 29 or more years experience, relative to having a physician who had graduated within the past 15 years, was associated with lower use of β-blockers (OR 0.71, 95% CI 0.60–0.84) and statins (OR 0.81, 95% CI 0.67–0.97).

Interpretation

Patients who received care from noncardiologists and physicians with at least 29 years of experience had substantially lower use of evidence-based drug therapies after discharge. Dissemination strategies should be devised to improve the prescribing of evidence-based medications by these physicians.The use of medications such as acetylsalicylic acid (ASA), β-blockers, angiotensin-modifying drugs (angiotensin-converting-enzyme [ACE] inhibitors and angiotensin-receptor blockers) and statins is a mainstay of secondary prevention of myocardial infarction. In a companion study published in this issue of CMAJ, we report substantial increases in the use of evidence-based drug therapies after discharge among elderly patients with myocardial infarction over a 14-year period.¹ However, despite temporal improvements, the prescribing of evidence-based drug therapies differed among hospitals in 2005.Studies from the late 1980s to the mid-1990s showed that the prescribing of evidence-based drug therapies was influenced by patient characteristics.^2–6 However, the extent to which postdischarge prescribing is influenced by patient, physician, hospital and community characteristics has not been extensively explored.Our objective was to identify patient, physician, hospital and community characteristics associated with the use of of evidence-based drug therapies after discharge among patients with myocardial infarction.