Sarcopenia Definitions and Their Associations With Mortality in Older Australian Women

Abstract

Objectives: To investigate the relationship of 4 sarcopenia definitions with long-term all-cause mortality risk in older Australian women.

Design: Data from the Perth Longitudinal Study in Aging Women from 2003 to 2013 was examined in this prospective cohort study. The 4 sarcopenia definitions were the United States Foundation for the National Institutes of Health (FNIH), the European Working Group on Sarcopenia in Older People (EWGSOP), and adapted FNIH (AUS-POP_F) and EWGSOP (AUS-POP_E) definitions using Australian population-specific cut-points [<2 standard deviation (SD)] below the mean of young healthy Australian women. All-cause mortality was captured via linked data systems.

Setting and participants: In total, 903 community-dwelling older Australian women (baseline mean age 79.9 ± 2.6 years) with concurrent measures of muscle strength (grip strength), physical function (timed-up-and-go; TUG) and appendicular lean mass (ALM) were included.

Measures: Cox-proportional hazards modeling was used to examine the relationship between sarcopenia definitions and mortality over 5 and 9.5 years.

Results: Baseline prevalence of sarcopenia by the 4 definitions differed substantially [FNIH (9.4%), EWGSOP (24.1%), AUS-POP_F (12.0%), AUS-POP_E (10.7%)]. EWGSOP and AUS-POP_E had increased age-adjusted hazard ratios (aHRs) for mortality over 5 years [aHR 1.88 95% confidence interval (CI) (1.24‒2.85), P < .01; aHR 2.52 95% CI (1.55‒4.09), P < .01, respectively] and 9.5 years (aHR 1.39 95% CI (1.06‒1.81), P = .02; aHR 1.94 95% CI (1.40‒2.69), P < .01, respectively). No such associations were observed for FNIH or AUS-POP_F. Sarcopenia components including weaker grip strength (per SD, 4.9 kg; 17%) and slower TUG (per SD, 3.1 seconds; 40%) but not ALM adjusted-variants (ALM/body mass index or ALM/height²) were associated with greater relative hazards for mortality over 9.5 years.

Conclusions/relevance: Unlike FNIH, the EWGSOP sarcopenia definition incorporating weak muscle strength and/or poor physical function was related to prognosis, as was the regionally adapted version of EWGSOP. Although sarcopenia definitions were not developed based on prognosis, this is an important consideration for globally standardizing the sarcopenia framework.

Keywords: Mortality; geriatrics; lean mass; muscle strength; physical function.