Prognostic value of domain-specific changes in physical function in frail older patients with heart failure

Background Improving physical functions in frail patients with heart failure (HF) can lead to a better prognosis. The Short Physical Performance Battery (SPPB) is an established prognostic tool in these patients; however, the prognostic significance of in-hospital changes in its individual components remains unclear. This study investigated whether changes in balance, gait speed, and the five-chair-stand test (5STS) during hospitalisation are differentially associated with all-cause and cause-specific mortality in frail older HF patients. Methods This retrospective observational study included 665 older (≥60 years) patients hospitalised for acute decompensated HF with a baseline SPPB score ≤9 points, which was used to define frailty. The SPPB was assessed at the initiation of in-hospital rehabilitation (baseline) and at discharge (follow-up). Patients were classified into two groups: improved (changes in each component >0 points) and non-improved (changes in each component ≤0 points). The main outcome was all-cause mortality. Secondary outcomes included mortality by cause of death (cardiovascular [CV] and non-CV), physical function at discharge (i.e., quadriceps isometric strength [QIS] and 6-minute walk distance [6MWD]), and quality of life (QOL) evaluated by the SF-36 physical functioning score. Kaplan–Meier curves with log-rank tests and multivariable Cox regression analysis, adjusted for clinical confounders, were used for mortality analyses. Analysis of covariance (ANCOVA) was used to compare physical functions and QOL. Results During a median follow-up of 1.70 years, 166 all-cause deaths occurred, including 94 CV and 72 non-CV deaths. Kaplan–Meier analysis demonstrated that improvements in the total SPPB score, gait speed, and 5STS were associated with significantly lower all-cause mortality, whereas improvements in balance were not. After adjusting for covariates, improvement in gait speed (adjusted hazard ratio [aHR] 0.73, 95% confidence interval [CI]: 0.46–0.97) and 5STS (aHR 0.86, 95% CI: 0.44–0.87) was associated with a lower risk of all-cause mortality. Regarding cause-specific mortality, improvement in gait speed was associated with a reduced risk of CV death (aHR 0.51, 95% CI: 0.32–0.83). In contrast, improvement in the 5STS was associated with a reduced risk of non-CV death (aHR 0.57, 95% CI: 0.34–0.95). ANCOVA demonstrated that patients who improved in gait speed or the 5STS had significantly higher QIS, longer 6MWD, and better QOL at discharge compared with non-improved patients (all p<0.001). In contrast, no significant differences were observed for balance. Conclusion In frail older HF patients, in-hospital improvement in dynamic SPPB components, especially gait speed and 5STS, was associated with lower all-cause mortality, and better physical functions and QOL. Serial assessment of individual SPPB components may support refined prognostic stratification and stage-specific rehabilitation strategies.