Severity of mobility limitation and adverse outcomes in heart failure

BACKGROUND: Mobility limitation is prevalent in patients with heart failure (HF), but the dose-response relationship between its severity and adverse outcomes remains unquantified. METHODS: We conducted a patient-level pooled analysis of two prospective Japanese cohort studies, including 2103 hospitalised patients with HF with no exclusion criteria. Mobility limitation at discharge was categorised into four levels: category I (independent outdoor walking), category II (indoor independence but requiring outdoor assistance), category III (requiring indoor assistance) and category IV (unable to walk). The primary endpoint was a 2-year composite of HF rehospitalisation or all-cause mortality. Adjusted analyses accounted for age, sex, comorbidities, biomarkers and medications. RESULTS: Among 2820.7 person-years of follow-up, 998 composite outcomes occurred. Incidence rates per 100 person-years for the primary outcome increased with mobility limitation severity: 24.9 (category I), 47.0 (II), 59.3 (III) and 84.8 (IV) (p for trend <0.001). Adjusted HRs (95% CI) using category I as reference were 1.22 (95% CI 1.04 to 1.45) for II, 1.39 (95% CI 1.11 to 1.73) for III and 1.71 (95% CI 1.34 to 2.20) for IV. While the graded association was clear for mortality, it was less evident for HF rehospitalisation alone, likely reflecting competing mortality risks. CONCLUSIONS: This study demonstrates a strong and graded association between mobility limitation severity and adverse outcomes in HF, suggesting its utility for refined risk stratification.