Assessment of SARC-F Sensitivity for Probable Sarcopenia Among Community-Dwelling Older Adults: Cross-Sectional Questionnaire Study

Abstract

Background: The European Working Group on Sarcopenia in Older People (EWGSOP2) recommends the use of the 5-item SARC-F questionnaire by clinicians to screen for probable sarcopenia. The recommended threshold of ≥4 has low sensitivity and high specificity in identifying probable sarcopenia. While this high threshold is capable of excluding clients without probable sarcopenia, difficulty lies in using this screening tool to identify clients with low muscle strength. Objective: This study aims to reassess the SARC-F as used in a primary care clinic for the determination of the incidence of probable sarcopenia and to determine if a test of handgrip strength is necessary for diagnosis of probable sarcopenia. Methods: We screened 204 patients ≥ 65 years (117 men, 87 women) during routine visits with the SARC F. Probable sarcopenia was defined by EWGSOP2 grip strength cut points (≤ 27 kg for men, ≤ 16 kg for women). Receiver operating characteristic (ROC) analysis identified the SARC F threshold that best balanced sensitivity and specificity. Results: Probable sarcopenia was present in 12% of participants. Age (73.9 ± 6.2 y) and BMI (29.5 ± 5.8 kg/m²) did not differ by sex, but men showed higher grip strength (36.3 ± 8.1 kg vs 22.4 ± 5.5 kg, P < .001) and lower SARC F scores (0.9 ± 1.7 vs 1.9 ± 2.3, P < .001). A SARC F cut point of ≥ 2 yielded an AUC of 0.77 (95% CI 0.67–0.88), with sensitivity 0.78, specificity 0.75, accuracy 0.77, PPV 0.31, and NPV 0.96. Grip strength differed significantly between screen positive and screen negative groups at both the ≥ 2 and ≥ 4 thresholds (P < .001). Conclusions: A SARC- F threshold of ≥2 is recommended as an optimal tradeoff between sensitivity and specificity when identifying community-dwelling older adults with probable sarcopenia. This is lower than the currently accepted recommendation of ≥4. Our findings promote the recommended early detection and treatment by medical professionals by the EWGSOP2 by improving the ability to identify individuals with low muscle strength with this screening procedure.