Developing Functional Capacity Thresholds for Diagnosis of Sarcopenia in Africa: the multi-country MUFASSA Study

Background Sarcopenia, the age-related decline in muscle strength and function, contributes to frailty, disability, and mortality. Aim To establish the first African-specific thresholds (AFRO-SARC) for sarcopenia diagnosis. Methods Population-representative samples of adults aged ≥40years were recruited in The Gambia, Zimbabwe and South Africa. Grip strength, gait speed, and chair-rise time(CRT) were assessed. Questionnaires and physical assessments captured clinical and anthropometric outcomes. Sex-specific thresholds were derived using distribution-based approaches using 40.0-49.9-year as referent group. Between-country comparability supported pooled thresholds. Prevalence of low muscle function and sarcopenia (low grip strength plus slow gait speed) was estimated and examined in relation to clinical outcomes. Results Among 5,274 adults, AFRO-SARC thresholds were, in men and women respectively: grip strength <28.0kg, <20.3kg; gait speed <0.50m/s, <0.47m/s; CRT >18.5s, >21.5s. Overall, 14.6% men and 16.6% women had low grip strength, 5.6% and 12.8% slow gait speed; 20.5% of men and 18.4% of women slow CRT. Sarcopenia prevalence was 2.3% in men and 3.7% in women; 7.3% in men and 9.1% in women aged ≥70years. AFRO-SARC-sarcopenia was associated with poor physical performance (SPPB≤8; Odds Ratio(ORs) 27.8-84.0), greater disability (ORs 1.9-26.9), low mid upper arm circumference (ORs 2.5-3.8 women and 3.5 men aged ≥70years), poorer Healthy Ageing Scores(β-2.3 to -13.0), and slower CRT amongst adults aged ≥70(β 4.3 -4.7; all p<0.01) supporting construct validity. Conclusions This study provides the first harmonised African thresholds for sarcopenia diagnosis. AFRO-SARC offers a practical, biologically-grounded and scalable approach with greater population specificity than existing criteria, providing a foundation for clinical assessment.