Post-myocardial infarction beta-blockers improve mortality but may decrease function in elderly nursing home patients

1. In this propensity-matched retrospective cohort study, elderly nursing home residents who used beta-blockers after an acute myocardial infarction, especially those with underlying cognitive or functional impairment, were more likely to have a decrease in function compared with those not using beta-blockers.

2. However, use of beta-blockers post-myocardial infarction had improved mortality. Re-hospitalization rates were similar across groups.

Evidence Rating Level: 2 (Good)

Study Rundown: While the use of beta-blockers after an acute myocardial infarction (AMI) is well established in reducing mortality, there may be some side effects (falls, bradycardia, etc.) which can offset these benefits in elderly patients. This retrospective cohort study aimed to study the association of beta-blockers after AMI with functional decline, mortality and re-hospitalization among long-stay nursing home residents 65 years or older.

Users of beta-blockers, particularly those with underlying cognitive or functional impairment, were more likely to experience a functional decline compared with non-users of beta-blockers. However, mortality amongst users of beta-blockers was lower. The rates of re-hospitalization were similar across both users and non-users of beta-blockers. There was no significant relationship between use of beta-blockers and functional decline in those with intact cognitive or mild dementia, or those with baseline functional independence. The strength of the study included the size and specificity of the cohort studied. Limitations included the observational nature and its associated bias, but the researchers used propensity matching to reduce this bias.

Click to read the study, published today JAMA Internal Medicine

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

In-Depth [retrospective cohort study]: This retrospective cohort study was conducted using Medicare Part A and Part D claims, Online Survey Certification and Reporting system for nursing home information, and the Minimum Data Set, which included assessments of nursing home residents in the USA. The study population included nursing home residents 65 years or older hospitalized for an AMI from May 2007 to March 2010 and lived in a nursing home at least 30 days before the hospitalization but were not on beta-blockers at least 4 months prior to the AMI. Patients who died, were rehospitalized within 2 weeks of index hospitalization, and those who did not return to the nursing home post-discharge were excluded. The main exposure of interest was use of a beta-blocker in the immediate post-hospitalization period. No specification of type or dose of beta-blocker was made. The primary outcome was functional decline, defined as a loss of 3 points on the validated Morris scale of independence in ADLs between prehospital baseline and on assessment 3 months post-discharge. Secondary outcomes include death and rehospitalization within 90 days of discharge. Propensity score-based methods and intention to treat methods were used for matching of beta-blocker users and non-users, and for statistical analysis.

The propensity-matched cohort included 5496 new users of beta-blockers and an equal number of non-users. Those who were on beta-blockers were more likely to experience functional decline (OR 1.14; 95%CI 1.02-1.28) as compared to non-users. The number needed to harm was 52. This risk of functional decline seemed to be modified by baseline cognitive and functional status, wherein those with moderate to severe cognitive impairment or functional dependency experienced worse functional decline. Those with intact cognition or functional independence actually had little evidence of functional decline. Lastly, those on beta-blockers had decreased risk of mortality (HR 0.74; 95%CI 0.67-0.83). Rates of re-hospitalization were similar across both groups (HR 1.06; 95%CI 0.98-1.14).

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