SARC-F: A symptom score to predict persons with sarcopenia at risk for poor functional outcomes

Background: A brief, inexpensive screening test for sarcopenia would be helpful for clinicians and their patients. To screen for persons with sarcopenia, we developed a simple five-item questionnaire (SARC-F) based on cardinal features or consequences of sarcopenia. Methods: We investigated the utility of SARC-F in the African American Health (AAH) study, Baltimore Longitudinal Study of Aging (BLSA), and National Health and Nutrition Examination Survey (NHANES). Internal consistency reliability for SARC-F was determined using Cronbach's alpha. We evaluated SARC-F factorial validity using principal components analysis and criterion validity by examining its association with exam-based indicators of sarcopenia. Construct validity was examined using cross-sectional and longitudinal differences among those with high (≥4) vs. low (<4) SARC-F scores for mortality and health outcomes. Results: SARC-F exhibited good internal consistency reliability and factorial, criterion, and construct validity. AAH participants with SARC-F scores≥4 had more Instrumental Activity of Daily Living (IADL) deficits, slower chair stand times, lower grip strength, lower short physical performance battery scores, and a higher likelihood of recent hospitalization and of having a gait speed of <0.8m/s. SARC-F scores≥4 in AAH also were associated with 6year IADL deficits, slower chair stand times, lower short physical performance battery scores, having a gait speed of <0.8m/s, being hospitalized recently, and mortality. SARC-F scores≥4 in the BLSA cohort were associated with having more IADL deficits and lower grip strength (both hands) in cross-sectional comparisons and with IADL deficits, lower grip strength (both hands), and mortality at follow-up. NHANES participants with SARC-F scores≥4 had slower 20ft walk times, had lower peak force knee extensor strength, and were more likely to have been hospitalized recently in cross-sectional analyses. Conclusions: The SARC-F proved internally consistent and valid for detecting persons at risk for adverse outcomes from sarcopenia in AAH, BLSA, and NHANES.