Low Muscle Mechanical Power, Worse Clinical Outcomes? A Cohort of Patients on Hemodialysis

Background and hypothesis: In older adults, low muscle mechanical power is an independent predictor of adverse clinical outcomes. In patients with chronic kidney disease, this has not yet been explored. In this study, we hypothesized that low muscle mechanical power is independently associated with increased risks of all-cause mortality and hospitalization in patients on hemodialysis. Methods: This study is a secondary analysis of the SARC-HD cohort, which enrolled patients from 19 dialysis centers across Brazil. Adults undergoing hemodialysis were assessed at baseline for relative muscle mechanical power using the five times sit-to-stand test (5-STS rel ). Low relative muscle mechanical power was defined based on sex– and age-specific lowest tertiles (p33) of STS rel values (W⋅kg −1 ) whithin our cohort. All-cause mortality and hospitalizations were collected through a 24-month follow-up period. Cox proportional hazards regression was modeled, with adjustment for clinically relevant confounders. Results: A total of 922 adults on hemodialysis were included (48.6% ≥60 years and 61.5% males), with 12.8% mortality and 35.4% hospitalization rates. Low muscle mechanical power was associated with an increased risk of all-cause mortality, with an adjusted hazard ratio (aHR) of 1.67 (95% CI: 1.15 – 2.41), but it was not associated with hospitalization (aHR=1.08, 95% CI: 0.87–1.36). In a subgroup analysis of age, the all-cause mortality outcome was significant in patients ≥ 60 years, with an aHR of 2.19 (95% CI: 1.41–3.40), but not in young (aHR=1.02, 95% CI: 0.50–2.10). Conclusions: In patients on hemodialysis, low muscle mechanical power was strongly associated with a greater mortality risk, particularly among older patients. These findings position low muscle mechanical power as a clinically and potentially relevant aging-related condition.