Translation, cross-cultural adaptation, and validation of fatigue severity scale into Bangla in patients with systemic lupus erythematosus

Objective: Fatigue is common in patients with systemic lupus erythematosus (SLE). Fatigue severity scale (FSS) is used to measure fatigue. This study was aimed to develop a culturally adapted Bangla version of the English FSS and to validate it. Methods: English version of FSS was translated into Bangla and adapted in the local sociocultural context, following the recommendations of Beaton et al. One hundred and twenty SLE patients were assessed in the Rheumatology Department of Bangabandhu Sheikh Mujib Medical University. Content validity of the adapted Bangla version was evaluated by item-level content validity index (I-CVI) and scale-level content validity index (S-CVI). Correlation between FSS and health assessment questionnaire-disability index (HAQ-DI) and 12 item short form health survey (SF-12) was measured for the assessment of convergent validity. Internal consistency and test-retest reliability were also assessed. Results: Our procedure had no problem with the content and language. I-CVI and S-CVI for each item was one. FSS showed strong positive correlation (> 0.7) with HAQ-DI and strong negative correlation (>-0.7) with SF-12. The scale demonstrated excellent internal consistency (Cronbach's alpha = 0.93) and test-retest reliability (intraclass correlation coefficient = 0.93). Conclusions: The adapted Bangla version of FSS is a reliable and valid instrument and can be recommended for the self-assessment of fatigue in SLE patients.