Validation of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument 2.0 in English- and Chinese-speaking patients in a multi-ethnic Singapore systemic sclerosis cohort

The aim of this study was to (1) translate the Gastrointestinal Tract Instrument (GIT) 2.0 from English to Chinese and (2) validate both versions in a multi-ethnic systemic sclerosis cohort in Singapore (SCORE). The English GIT2.0 was translated to Chinese using a standard forward-backward translation approach. Psychometric evaluation of the GIT2.0 included internal consistency reliability (using Cronbach’s alpha), test-retest reliability (using intra-class correlation coefficient (ICC)), scale level factor analysis, and construct validity (using Spearman correlation) against the modified Scleroderma Health Assessment Questionnaire (S-HAQ) and the SF-36 v2. Most of the patients were females (88.6%) and Chinese (78.2%), with mean (SD) age of 51.0 (13.0) years and median disease duration of 4.5 years. We administered English (n = 146) and Chinese (n = 74) GIT2.0. The mean (SD) total GIT score was 0.29 (0.37). There was good internal consistency (Cronbach’s alpha >0.70 for all subscales) and good test-retest reliability for the scale and all subscales (ICC 0.71–0.92) except for “diarrhoea” (ICC = 0.54). Our hypothesised a priori construct validity was supported by moderate correlations between the total GIT score and S-HAQ GI subscale (r = 0.446), and the social functioning subscale and SF36v2 role-social domain (r = 0.337), and weak-to-moderate correlation between the emotional subscale and SF-36v2 role-emotional (r = 0.295) and mental health (r = 0.298) domains and mental component summary (r = 0.356). Exploratory factor analysis of the seven subscales yielded a two-factor solution explaining 69.63% of the total variance. This study provides evidence for the reliability and validity of the English and Chinese GIT2.0 to be used in Singapore for research and routine practice.