Tradeoffs in Medication Adherence after Acute Myocardial Infarction Confer Different Mortality Risks

For patients with acute myocardial infarction, nonadherence to beta blockers doesn’t reduce mortality—as long as they are taking their prescribed angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) and statins, reports a study in the Journal of the American College of Cardiology.

The researchers analyzed “tradeoffs in adherence” to multiple preventive therapies using data on nearly 91,000 Medicare beneficiaries aged 65 or older with acute myocardial infarction between 2008 and 2010. All patients survived at least 180 days after being hospitalized for acute myocardial infarction and received prescriptions for ACEIs/ARBs, beta blockers, and statins.

Medicare Part D prescription claims were used to analyze adherence to the three classes of drugs, and adherence was defined as at least 80% of days covered for each medication. Mortality was compared for patients who were adherent to none, one, two, or all three medications. Follow-up for mortality continued for 18 months after the 180-day postdischarge period.

Overall, 51.5% of patients were nonadherent to at least one of the three medications: 30.7% were nonadherent to ACEIs/ARBS, 23.8% to beta blockers, and 23.0% to statins. During mean follow-up of about 1 year, 10.6% of patients died. Adjusted mortality was 9.3% for patients adherent to all three medications, compared to 14.3% for those nonadherent to all three therapies.

About 9% of patients were adherent to ACEIs/ARBs and statins, but not beta blockers. In this group of patients, mortality was not significantly different from that for those who were adherent to all three medications. Adjusted hazard ratios for mortality were 1.65 for those nonadherent to all three therapies, 1.32 for those adherent to beta blockers only, and 1.26 for those adherent to statins only. For those adherent to ACEIs/ARBS only, the adjusted hazard ratio was 1.19; 1.17 for those adherent to beta blockers and statins only, and 1.12 for those adherent to ACEIs/ARBs and beta blockers only.

The benefits of adherence to ACEIs/ARBs were greater in patients with diabetes on subgroup analysis. In contrast, the directions of the associations were generally similar in other subgroups. The effects of adherence tradeoffs tended to be larger in men than women and in older compared to younger patients.

Suboptimal adherence to secondary preventive therapies after acute myocardial infarction is well documented. Few clinical trial data are available to guide the balance of risks and benefits of these medications, particularly in older adults taking many different prescriptions.

The new findings confirm that only about half of older adults are adherent to all three recommended medications after acute myocardial infarction. Those who are adherent to ACEIs/ARBs and statins show no significant reduction in one-year mortality, compared to those adherent to all three medications. All other nonadherence groups show increased mortality risks.

“[L]ong-term adherence to ACEIs/ARBs and statins may be more important than adherence to beta blockers after acute myocardial infarction,” the investigators conclude. They emphasize the need for further studies to clarify the clinical implications of their findings [Korhonen MJ, et al. Adherence tradeoff to multiple preventive therapies and all-cause mortality after acute myocardial infarction. J Am Coll Cardiol 2017; 70:1543−1554].

October/November 2017 (Vol. 9, Number 10 & 11)