Predictive value of sarcopenia components for all-cause mortality findings from population-based cohorts

Authors: WESTBURY, LEO - University Of Southampton; HARVEY, NICHOLAS - University Of Southampton; BEAUDART, CHARLOTTE - University Of Namur; BRUYERE, OLIVIER - University Of Liege; CAULEY, JANE - University Of Pittsburgh; CAWTHON, PEGGY - University Of California San Francisco (UCSF); CRUZ-JENTOFT, ALFONSO - Instituto Ramon Y Cajal De Investigacion Sanitaria (IRYCIS); CURTIS, ELIZABETH - University Of Southampton; ENSRUD, KRISTINE - University Of Minnesota; FIELDING, ROGER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; JOHANSSON, HELENA - University Of Gothenburg; KANIS, JOHN - University Of Sheffield; KARLSSON, MAGNUS - Lund University; LANE, NANCY - University Of California, Davis; LENGELE, LAETITIA - Universite Catholique; LORENTZON, MATTIAS - Sahlgrenska University Hospital; MCCLOSKEY, EUGENE - University Of Sheffield; MELLSTROM, DAN - University Of Gothenburg; NEWMAN, ANNE - University Of Pittsburgh; OHLSSON, CLAES - Sahlgrenska University Hospital; ORWOLL, ERIC - Oregon Health & Science University; REGINSTER, JEAN-YVES - King Saud University; ROBOM, EVA - Uppsala University; ROSENGREN, BJORN - Lund University; SCHOUSBOE, JOHN - University Of Minnesota; DENNISON, ELAINE - University Of Southampton; COOPER, CYRUS - University Of Southampton

Submitted to: Aging Clinical and Experimental Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2024
Publication Date: 6/6/2024
Citation: Westbury, L.D., Harvey, N.C., Beaudart, C., Bruyere, O., Cauley, J.A., Cawthon, P., Cruz-Jentoft, A.J., Curtis, E.M., Ensrud, K., Fielding, R., Johansson, H., Kanis, J.A., Karlsson, M.K., Lane, N., Lengele, L., Lorentzon, M., Mccloskey, E., Mellstrom, D., Newman, A.B., Ohlsson, C., Orwoll, E., Reginster, J., Robom, E., Rosengren, B.E., Schousboe, J.T., Dennison, E.M., Cooper, C. 2024. Predictive value of sarcopenia components for all-cause mortality findings from population-based cohorts. Aging Clinical and Experimental Research. https://doi.org/10.1007/s40520-024-02783-x.
DOI: https://doi.org/10.1007/s40520-024-02783-x

Interpretive Summary: Muscle weakness and walking slowly are included in many definitions of sarcopenia and are linked to increased risk of death. In this large multi-national study, we examined the influence of muscle weakness and walking slowly on the risk of death when other more common risk factors for death are considered such as smoking, alcohol consumption and physical inactivity. We found that muscle weakness and slow walking were associated with increased risk of death even when accounting for these other well established risk factors. However, there was only a modest added increase in risk in these analyses suggesting a relatively small effect of muscle weakness and walking slowly on risk of death.

Technical Abstract: Background: Low grip strength and gait speed are included in many sarcopenia definitions and are strongly associated with mortality. However, there has been limited investigation of the additional risk explained by such sarcopenia components over and above more readily obtainable clinical risk factors. We aimed to quantify this using a multinational assembly of cohort studies. Methods: Participants from the Health, Aging and Body Composition (Health ABC) Study, Osteoporotic Fractures in Men (MrOS) Study (United States), and the Hertfordshire Cohort Study (HCS) were analysed. Appendicular lean mass (ALM) was ascertained using DXA; muscle strength by grip dynamometry; and usual gait speed over courses of 2.4 to 6m. Deaths were recorded and verified. Associations between sarcopenia components and mortality were examined using Cox regression with cohort as a random effect. The strength of association regarding each sarcopenia component and the discriminative capacity of models according to Harrell's Concordance Index (C-index) were examined with and without adjustment for established mortality risk factors. Results: Mean (SD) age of participants (n=8362) was 73.8 (5.1) years; 5231 (62.6%) participants died during a median follow-up time of 13.3 years. Grip strength (hazard ratio (95% CI) per SD decrease: 1.14 (1.10, 1.19)) and gait speed (1.21 (1.17, 1.26)), but not ALM index (1.01 (0.95, 1.06)), were associated with mortality in mutually-adjusted models after accounting for the covariates age, sex, BMI, smoking status, alcohol consumption, physical activity, ethnicity, education, history of fractures and falls, femoral neck bone mineral density (BMD), self-rated health, cognitive function and number of comorbidities. However, whilst a model including only the covariate set gave a C-index of 0.69 (95% CI: (0.68, 0.70)), this was only increased to 0.70 (0.69, 0.70) with inclusion of grip strength and gait speed. Furthermore, a model containing only age and sex as exposures gave a C-index of 0.65 (0.64, 0.66), which only increased to 0.67 (0.67, 0.68) after inclusion of these two measures. Conclusions: Low grip strength and gait speed were associated with increased risk of death during follow-up, independent of established mortality risk factors. However, the magnitude of the effect was relatively small, and these measures provided only minimal improvement in discriminative capacity regarding mortality. Therefore, measurement of grip strength and gait speed may generate only modest adjunctive risk information compared with other more readily obtainable clinical risk factors.