Muscle strength and physical performance as predictors of mortality, hospitalization, and disability in the oldest old

Objectives: To evaluate the predictive value of muscle strength and physical performance in the oldest old for all-cause mortality; hospitalization; and the onset of disability, defined as a decline in activities of daily living (ADLs), independent of muscle mass, inflammatory markers, and comorbidities.

Design: A prospective, observational, population-based follow-up study.

Setting: Three well-circumscribed areas of Belgium.

Participants: Five hundred sixty participants aged 80 and older were followed for 33.5 months (interquartile range 31.1-35.6 months).

Measurements: Grip strength, Short Physical Performance Battery (SPPB) score, and muscle mass were measured at baseline; ADLs at baseline and after 20 months; and all-cause mortality and time to first hospitalization from inclusion onward. Kaplan-Meier curves and Cox proportional hazards models were calculated for all-cause mortality and hospitalization. Logistic regression analysis was used to determine predictors of decline in ADLs.

Results: Kaplan-Meier curves showed significantly higher all-cause mortality and hospitalization in subjects in the lowest tertile of grip strength and SPPB score. The adjusted Cox proportional hazards model showed that participants with high grip strength or a high SPPB score had a lower risk of mortality and hospitalization, independent of muscle mass, inflammatory markers, and comorbidity. A relationship was found between SPPB score and decline in ADLs, independent of muscle mass, inflammation, and comorbidity.

Conclusion: In people aged 80 and older, physical performance is a strong predictor of mortality, hospitalization, and disability, and muscle strength is a strong predictor of mortality and hospitalization. All of these relationships were independent of muscle mass, inflammatory markers, and comorbidity.