Association of β-Blockers With Functional Outcomes, Death, and Rehospitalization in Older Nursing Home Residents After Acute Myocardial Infarction

Abstract

Importance: Although β-blockers are a mainstay of treatment after acute myocardial infarction (AMI), these medications are commonly not prescribed for older nursing home residents after AMI, in part owing to concerns about potential functional harms and uncertainty of benefit.

Objective: To study the association of β-blockers after AMI with functional decline, mortality, and rehospitalization among long-stay nursing home residents 65 years or older.

Design, setting, and participants: This cohort study of nursing home residents with AMI from May 1, 2007, to March 31, 2010, used national data from the Minimum Data Set, version 2.0, and Medicare Parts A and D. Individuals with β-blocker use before AMI were excluded. Propensity score-based methods were used to compare outcomes in people who did vs did not initiate β-blocker therapy after AMI hospitalization.

Main outcomes and measures: Functional decline, death, and rehospitalization in the first 90 days after AMI. Functional status was measured using the Morris scale of independence in activities of daily living.

Results: The initial cohort of 15 720 patients (11 140 women [70.9%] and 4580 men [29.1%]; mean [SD] age, 83 [8] years) included 8953 new β-blocker users and 6767 nonusers. The propensity-matched cohort included 5496 new users of β-blockers and an equal number of nonusers for a total cohort of 10 992 participants (7788 women [70.9%]; 3204 men [29.1%]; mean [SD] age, 84 [8] years). Users of β-blockers were more likely than nonusers to experience functional decline (odds ratio [OR], 1.14; 95% CI, 1.02-1.28), with a number needed to harm of 52 (95% CI, 32-141). Conversely, β-blocker users were less likely than nonusers to die (hazard ratio [HR], 0.74; 95% CI, 0.67-0.83) and had similar rates of rehospitalization (HR, 1.06; 95% CI, 0.98-1.14). Nursing home residents with moderate or severe cognitive impairment or severe functional dependency were particularly likely to experience functional decline from β-blockers (OR, 1.34; 95% CI, 1.11-1.61 and OR, 1.32; 95% CI, 1.10-1.59, respectively). In contrast, little evidence of functional decline due to β-blockers was found in participants with intact cognition or mild dementia (OR, 1.03; 95% CI, 0.89-1.20; P = .03 for effect modification) or in those in the best (OR, 0.99; 95% CI, 0.77-1.26) and intermediate (OR, 1.05; 95% CI, 0.86-1.27) tertiles of functional independence (P = .06 for effect modification). Mortality benefits of β-blockers were similar across all subgroups.

Conclusions and relevance: Use of β-blockers after AMI is associated with functional decline in older nursing home residents with substantial cognitive or functional impairment, but not in those with relatively preserved mental and functional abilities. Use of β-blockers yielded a considerable mortality benefit in all groups.

Figure 1. Association between beta-blocker use and death and re-hospitalization

Panel A shows time to death among beta blocker users and non-users. Panel B shows time to re-hospitalization in the 2 groups. There are no events in the first 14 days after hospital discharge because subjects who left the nursing home for any reason in the first 14 days after hospital discharge were excluded from analysis. Red lines are beta blocker-users; blue lines are non-users. Shaded areas are the 95% confidence intervals around each survival curve.

Figure 2. Impact of beta blockers on functional decline and death: subgroup analyses

P values show the significance of effect modification on the multiplicative scale. Values for additive effect modification are as follows, and are expressed as relative excess risk due to interaction (RERI). For the outcome of functional decline, RERI (95% CI) for moderate ADL dependence is 0.11 (−0.36 to 0.58), P=0.65 and for high ADL dependence is 0.66 (0.20 to 1.13), p<0.01, indicating positive additive interaction for high ADL dependence; RERI (95% CI) for worse cognitive performance score is 0.08 (−0.12 to 0.29), P=.42; RERI (95% CI) for higher age is −0.14 (−0.38 to 0.11), P=.27; RERI (95% CI) for ICU/CCU stay is −0.03 (−0.29 to 0.24), P=0.85. For the outcome of death, RERI (95% CI) for moderate ADL dependence is −0.35 (−0.70 to 0.01), P=0.05, indicating potential negative additive interaction, and for higher ADL dependence is −0.19 (−0.54 to 0.17), p=0.31; RERI (95% CI) for worse cognitive performance score is −0.15 (−0.42 to 0.12), P=.29; RERI (95% CI) for higher age is 0.00 (−0.21 to 0.22), P=.97; RERI (95% CI) for ICU/CCU stay is −0.05 (−0.26 to 0.14), P=0.60. *ADL score <14 corresponds to independence or requiring limited assistance with ADLs; ADL score 14–19 corresponds to requiring extensive assistance; and ADL score 20 or above corresponds to extensive dependence on others to perform ADLs. *CPS score 0–2 corresponds to normal to mildly impaired cognition including mild dementia. CPS score 3–6 corresponds to moderate or severe cognitive impairment (roughly equivalent to a Folstein Mini Mental State Exam score of 14/30 or lower).