SARC-F and modified versions using arm and calf circumference: Diagnostic performance for sarcopenia screening and the impact of obesity.

Abstract

SARC-F is limited by low sensitivity for sarcopenia identification. As surrogates of muscle mass, mid-arm circumference (MAC) and/or calf circumference have been proposed as additions to SARC-F to enhance sarcopenia identification. The aim of this study was to evaluate the diagnostic performance of SARC-F, SARC-CalF, SARC-F + MAC, and SARC-CalF + MAC in sarcopenia detection, and to assess the impact of obesity on their diagnostic performance. We studied 230 healthy non-frail community-dwelling older adults age >50 years. We performed receiver operating characteristic curve analysis for SARC-F, SARC-CalF, SARC-F + MAC and SARC-CalF + MAC against sarcopenia diagnosed by the Asian Working Group for Sarcopenia (AWGS) 2019 as the reference standard. Obesity was defined by high waist circumference (men ≥90 cm, women ≥80 cm). We performed subgroup analysis to compare between obese and non-obese groups. The prevalence of sarcopenia was 27.0% by AWGS 2019. SARC-CalF + MAC had the best diagnostic performance (area under the curve [AUC] 0.74, 95% confidence interval [CI] 0.67-0.81; sensitivity 66.1%; specificity 69.1%), followed by SARC-CalF (AUC 0.70, 95% CI 0.62-0.78; sensitivity 21.0%; specificity 95.8%). SARC-F (AUC 0.57, 95% CI 0.49-0.66; sensitivity 0%; specificity 100%) performed significantly worsethan its modified versions (P < 0.05). There was higher accuracy of sarcopenia identification in obese compared with non-obese groups for SARC-F + MAC (AUC 0.75, 95% CI 0.65-0.85 vs. 0.58, 95% CI 0.46-0.70) and SARC-CalF + MAC (AUC 0.75, 95% CI 0.66-0.85 vs. 0.70, 95% CI 0.59-0.81). The addition of arm circumference to SARC-CalF confers better diagnostic accuracy for sarcopenia identification, especially in the obese group. Thus, MAC may complement SARC-CalF for community screening of sarcopenia amongst healthy community-dwelling older adults by increasing sensitivity for the detection of sarcopenic obesity. Geriatr Gerontol Int 2024; 24: 182-188.