Identification of sarcopenia components that discriminate slow walking speed: a pooled data analysis

Authors: MANINI, TODD - UNIVERSITY OF FLORIDA; PATEL, SHEENA - CALIFORNIA PACIFIC MEDICAL CENTER RESEARCH INSTITUTE; NEWMAN, ANNE - UNIVERSITY OF PITTSBURGH; TRAVISON, THOMAS - HARVARD UNIVERSITY; KIEL, DOUGLAS - HARVARD UNIVERSITY; SHARDELL, MICHELLE - NATIONAL INSTITUTES OF HEALTH (NIH); PENCINA, KAROL - HARVARD UNIVERSITY; WILSON, KEVIN - HOLOGIC, INC.; KELLY, THOMAS - HOLOGIC, INC.; MASARO, JOSEPH - BOSTON UNIVERSITY; FIELDING, ROGER - JEAN MAYER HUMAN NUTRITION RESEARCH CENTER ON AGING AT TUFTS UNIVERSITY; MAGAZINER, JAY - UNIVERSITY OF MARYLAND; CORREA-DE-ARAUJO, ROSALY - NATIONAL INSTITUTE ON AGING (NIA, NIH); KWOK, TIMOTHY - THE CHINESE UNIVERSITY OF HONG KONG (CUHK); HIRANI, VASANT - UNIVERSITY OF SYDNEY; KARLSSON, MAGNUS - LUND UNIVERSITY; D'AGOSTINO, RALPH - BOSTON UNIVERSITY; MELLSTROM, DAN - UNIVERSITY OF GOTHENBURG; OHLSSON, CLAES - UNIVERSITY OF GOTHENBURG; RIBOM, EVA - UPPSALA UNIVERSITY; JORDAN, JOANNE - UNIVERSITY OF NORTH CAROLINA; BHASIN, SHALENDER - HARVARD UNIVERSITY; CAWTHON, PEGGY - CALIFORNIA PACIFIC MEDICAL CENTER

Submitted to: Journal of the American Geriatrics Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2020
Publication Date: 7/7/2020
Citation: Manini, T.M., Patel, S., Newman, A.B., Travison, T.G., Kiel, D.P., Shardell, M., Pencina, K., Wilson, K.E., Kelly, T.L., Masaro, J.M., Fielding, R.A., Magaziner, J., Correa-de-Araujo, R., Kwok, T.C., Hirani, V., Karlsson, M.K., D'Agostino, R., Mellstrom, D., Ohlsson, C., Ribom, E., Jordan, J.M., Bhasin, S., Cawthon, P.M. 2020. Identification of sarcopenia components that discriminate slow walking speed: a pooled data analysis. Journal of the American Geriatrics Society. 68(7):1419-1428. https://doi.org/10.1111/jgs.16524.
DOI: https://doi.org/10.1111/jgs.16524

Interpretive Summary: The Sarcopenia Definitions and Outcomes Consortium (SDOC) sought to identify cut-points for muscle strength and muscle mass measures that discriminate older adults with slow walking speed. This paper presents the core analyses used to guide the SDOC position statements. To do this we studied 8 cohorts of community-dwelling older adults (~14,000 men and ~5,000 women). We used a statistical approach called classification and regression trees to select which measures best discriminate slow-walkers. Muscle weakness by grip strength was found to the best discriminating variable for slowness in men and women. Men with weakness by grip strength were about 4 times more likely to be slow walkers than those without weakness. Women with weakness by grip strength were 2 times more likely to be slow walkers than women without weakness. Grip strength weakness consistently discriminated older adults with slowness. Muscle mass was not found to be a primary discriminator of slowness.

Technical Abstract: BACKGROUND: The Sarcopenia Definitions and Outcomes Consortium (SDOC) sought to identify cut points for muscle strength and body composition measures derived from dual-energy x-ray absorptiometry (DXA) that discriminate older adults with slow walking speed. This article presents the core analyses used to guide the SDOC position statements. DESIGN: Cross-sectional data analyses of pooled data. SETTING: University-based research assessment centers. PARTICIPANTS: Community-dwelling men (n = 13,652) and women: (n = 5,115) with information on lean mass by DXA, grip strength (GR), and walking speed. MEASUREMENTS: Thirty-five candidate sarcopenia variables were entered into sex-stratified classification and regression tree (CART) models to agnostically choose variables and cut points that discriminate slow walkers (<0.80 m/s). Models with alternative walking speed outcomes were also evaluated (<0.60 and <1.0 m/s and walking speed treated continuously). RESULTS: CART models identified GR/body mass index (GRBMI) and GR/total body fat (GRTBF) as the primary discriminating variables for slowness in men and women, respectively. Men with GRBMI of 1.05 kg/kg/m2 or less were approximately four times more likely to be slow walkers than those with GRBMI of greater than 1.05 kg/kg/m2. Women with GRTBF of less than 0.65 kg/kg were twice as likely to be slow walkers than women with GRTBF of 0.65 kg/kg or greater. Models with alternative walking speed outcomes selected only functions of GR as primary discriminators of slowness in both men and women. DXA-derived lean mass measures did not consistently discriminate slow walkers. CONCLUSION: GR with and without adjustments for body size and composition consistently discriminated older adults with slowness. CART models did not select DXA-based lean mass as a primary discriminator of slowness. These results were presented to an SDOC Consensus Panel, who used them and other information to develop the SDOC Position Statements.