Cardiac rehabilitation and frailty: a systematic review and meta-analysis

Aims: Frailty among cardiac rehabilitation (CR) participants is associated with worse health outcomes. However, no literature synthesis has quantified the relationship between frailty and CR outcomes. The purpose of this study was to examine frailty prevalence at CR admission, frailty changes during CR, and whether frailty is associated with adverse outcomes following CR. Methods and results: We searched CINAHL, EMBASE, and MEDLINE for studies published from 2000 to 2023. Eligible studies included a validated frailty measure, published in English. Two reviewers independently screened articles and abstracted data. Outcome measures included admission frailty prevalence, frailty and physical function changes, and post-CR hospitalization and mortality. Observational and randomized trials were meta-analysed separately using inverse variance random-effects models. In total, 34 peer reviewed articles (26 observational, 8 randomized trials; 19 360 participants) were included. Admission frailty prevalence was 46% [95% CI 29-62%] and 40% [95% CI 28-52%] as measured by Frailty Index and Kihon Checklist (14 studies) and Frailty Phenotype (11 studies), respectively. Frailty improved following CR participation (standardized mean difference (SMD): 0.68, 95% CI 0.37-0.99; P < 0.0001; six studies). Meta-analysis of observational studies revealed higher admission frailty and increased participants' risk of all-cause mortality (hazard ratio: 9.24, 95% CI 2.93-29.16; P = 0.0001; four studies). Frailer participants at admission had worse physical health outcomes, but improved over the course of CR. Conclusion: High variability in frailty tools and CR designs was observed, and randomized controlled trial contributions were limited. The prevalence of frailty is high in CR and is associated with greater mortality risk; however, CR improves frailty and physical health outcomes.