Translation and validation of the Korean version of the Sarcopenia Quality of Life (SarQoL-K®) questionnaire and applicability with the SARC-F screening tool

Purpose The purpose of this paper was to translate and validate into the Korea language and setting the Sarcopenia Quality of Life (SarQoL (R)) questionnaire. Methods The participants consisted of 450 individuals in Namgaram-2 cohort who were followed up in 2019-2020. The study participants were divided into four groups: (1) SARC-F < 4, (2) SARC-F >= 4 and robust grip strength, (3) SARC-F >= 4, low grip strength, robust muscle mass, (4) SARC-F >= 4, low grip strength, and low muscle mass. To assess construct validity, population with sarcopenia-associated symptoms (SARC-F >= 4) apart from the Korean SarQoL (SarQoL-K (R)) completed the Korean versions of two generic questionnaires, the Short Form-36 and the EuroQoL 5-dimension. To validate the Korean SarQoL (R), we assessed its validity (discriminative power, construct validity), reliability (internal consistency, test-retest reliability), and floor/ceiling effects. Results The SarQoL-K (R) questionnaire was translated without major difficulties. The mean SarQoL-K scores were 72.9 (95%, CI; 71.2-74.6) in SARC-F < 4, 54.6 (95%, CI; 50.7-58.3) in SARC-F >= 4 and robust grip strength, 47.0 (95%, CI; 43.8-50.1) in SARC-F >= 4, low grip strength, robust muscle mass, 46.6 (95%, CI; 43.0-50.1) in SARC-F >= 4, low grip strength, and low muscle mass. The results indicated good discriminative power across each four groups (p < 0.001), high internal consistency (Cronbach's alpha of 0.866), and excellent test-retest reliability (ICC = 0.977, 95% CI 0.975-0.979). No floor- or ceiling-effects were observed. Conclusions This is the first study to confirm the reliability and validity of the Korean version of the SarQoL (R). We demonstrated that the population with sarcopenia-associated symptoms (determined using the SARC-F questionnaire) has a lower quality of life.