Psychometric performance of the Kannada version of sarcopenia quality of life questionnaire (SarQoL(®))

BACKGROUND: The Sarcopenia Quality of Life (SarQoL®) is a patient reported quality-of-life questionnaire specific to sarcopenia. In the Indian context, its availability is limited to Hindi, Marathi and Bengali vernacular languages. AIMS: This study aimed to translate, cross-culturally adapt the SarQoL® questionnaire into Kannada and investigate its psychometric properties. METHODS: The SarQoL®-English version was translated into Kannada with the developer’s permission and in accordance with their requirements. To validate the discriminative power, internal consistency and floor and ceiling effect of the SarQoL®-Kannada questionnaire were assessed in the first step. In the second step, the construct validity and the test–retest reliability of the SarQoL®-Kannada was determined. RESULT: There was no difficulty in the translation process. A total of n = 114 participants (sarcopenic participants n = 45 and n = 69 non-sarcopenic participants) were included. The good discriminative power of the SarQoL®-Kannada questionnaire {quality of life for sarcopenic subjects [56.43 ± 11.32] vs. non-sarcopenic ones [79.38 ± 8.16], p < 0.001}. High internal consistency (Cronbach’s alpha coefficient was 0.904) and no ceiling/ floor effect were reflected. Excellent test–retest reliability (intraclass correlation coefficient was 0.97, 95% CI 0.92–0.98) were found. A good convergent and divergent validity with similar and different domains of WHOQOL-BREF was observed, while EQ-5D-3L had good convergent and weak divergent validity. CONCLUSION: The SarQoL®-Kannada questionnaire is valid, consistent and reliable for the measurement of quality of life of sarcopenic participants. SarQoL®-Kannada questionnaire is now available to be used in clinical practice and as a treatment outcome indicator in research. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12891-023-06559-8.