Lower limb function and 10-year survival in population aged 75 years and older

Abstract

Background: Scientific societies recommend assessing lower limb function in usual clinical practice. The Short Physical Performance Battery (SPPB) is one of the most validated tools to assess this, but its capacity to predict long-term mortality in very old population attending primary care has not been studied.

Objective: To assess the ability of the SPPB to predict 10-year survival in individuals aged 75 and over.

Methods: Prospective cohort study with a 10-year follow-up. A representative sample of people aged 75 years or older without severe dependence (Barthel Index > 20) treated at a Spanish primary care centre (n = 315). Baseline evaluation included geriatric assessment with most well-known death predictors. The three SPPB subtasks (standing balance, walking speed and chair stand tests) were administered. Kaplan-Meier curves and Cox proportional hazard models were calculated for all-cause mortality.

Results: Mean age was 81.9 years (60.6% female). Ten-year survival of elders with SPPB score <7 and ≥7 was 0.23 and 0.37 (P < 0.001), respectively. This difference remained statistically significant in the Cox model adjusted by age, gender, number of drugs prescribed, cognitive status, body mass index and visual sharpness (adjusted hazard ratio = 1.37; 95% confidence interval: 1.01-1.86). Also, walking speed and chair stand subtasks were both individual-independent predictors of 10-year survival.

Conclusions: Our findings indicate that SPPB is an independent predictor of long-term survival. The chair stand subtask could be a predictor as useful as the full performance battery, becoming a good alternative for primary care where the burden of performing all three subtasks could be excessive.

Keywords: Aged; cohort study; lower extremity function; physical performance; survival..