Performance of the SarQoL quality of life tool in a UK population of older people with probable sarcopenia and implications for use in clinical trials: findings from the SarcNet registry.

BACKGROUND: The Sarcopenia Quality of Life (SarQoL) questionnaire is a disease-specific sarcopenia quality of life tool. We aimed to independently assess SarQoL with a particular focus on its suitability as a clinical trial outcome measure. METHODS: We analysed data from the UK Sarcopenia Network and Registry. Measures of physical performance and lean mass were collected at baseline. SarQoL and the Strength, Assistance, Rise, Climb - Falls (SARC-F) questionnaire (to assess functional ability) were collected at both baseline and six-month follow-up. Global changes in fitness and quality of life at 6 months were elicited on seven-point Likert scales. Internal consistency was assessed using Cronbach's alpha. Responsiveness (Cohen's d and Guyatt coefficients) and minimum clinically important differences were calculated for participants reporting slight improvement or worsening in their global scores. Concurrent validity was assessed by correlating baseline SarQoL scores with measures of physical performance and functional ability. RESULTS: We analysed data from 147 participants, 125 of whom underwent follow up assessment; mean age 78 years; 72 (49%) were women. Internal consistency was good; Cronbach's alpha was 0.944 at baseline and 0.732 at telephone follow-up. Correlation between baseline and follow-up SarQoL was weak (r = 0.27; p = 0.03). The minimum clinically important improvement ranged from 5 to 21 points giving trial sample size estimates of 25-100 participants. SarQoL scores were moderately correlated with handgrip (r = 0.37; p < 0.001), SARC-F (r = - 0.45; p < 0.001), short physical performance battery (r = 0.48; p < 0.001) and 4-m walk speed (r = 0.48; p < 0.001). CONCLUSIONS: SarQoL has acceptable performance in older UK participants with probable sarcopenia and is sufficiently responsive for use in clinical trials for sarcopenia.