Validation of the 7-day FABPRO-GI questionnaire in Turkish Fabry disease patients

Background Gastrointestinal (GI) symptoms affect over 50% of patients with Fabry disease (FD) and significantly impair quality of life. The 7-day FABry Disease Patient-Reported Outcome-Gastro intestinal (FABPRO-GI) is the first disease-specific instrument for assessing GI symptoms in FD. However, psychometric validation beyond content validity has not been published. We aimed to evaluate the psychometric properties of the Turkish version of the 7-day FABPRO-GI. Methods This cross-sectional validation study included 53 patients with genetically confirmed FD from Turkey. Participants completed both the Turkish 7-day FABPRO-GI (8 severity items, 0–10 scale) and the Gastrointestinal Symptom Rating Scale (GSRS; 5 domains, 1–7 scale). We assessed internal consistency, floor/ceiling effects, convergent and discriminant validity, association with clinical variables, multiple regression analysis, and structural equation modeling (SEM). Results The FABPRO-GI demonstrated excellent internal consistency (Cronbach’s alpha = 0.904). Convergent validity was supported by strong correlations between conceptually similar FABPRO-GI items and GSRS domains and by a strong correlation between total FABPRO-GI and GSRS scores ( r = 0.798, p < 0.001). Discriminant validity was supported by the absence of correlation between FABPRO-GI constipation and GSRS diarrhea ( r = 0.018, p = 0.898). In SEM, GSRS and FABPRO-GI latent factors showed a strong structural association (β = 0.93, p = 0.002), although overall model fit was suboptimal. In multiple regression, FABPRO-GI scores were independently associated with potassium, lyso-Gb3, age, diabetes, triglycerides, body mass index, and AST. Conclusions The Turkish version of the 7-day FABPRO-GI demonstrates excellent reliability and construct validity. This is the first study to provide psychometric validation of the FABPRO-GI beyond content validity, supporting its use in Turkish patients with Fabry disease; test-retest reliability and responsiveness to change require further evaluation. Clinical trial number Not applicable.