Translation, cultural adaptation, and validation of the Bath questionnaires and HAQ-S in Hindi for Indian patients with ankylosing spondylitis

The disease activity and functional impact of ankylosing spondylitis (AS) is currently measured through various questionnaire instruments, the most popular of which are the Bath indices. However, Hindi versions for use in Indian patients are not available. This study aimed to fill this lacuna. Translation and cross-cultural adaptation of the instruments—Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitits Metrology Index (BASMI), Bath Ankylosing Spondylitis Patient Global Score (BAS-G), and Health Assessment Questionnaire-Spondyloarthropathy (HAQ-S)—were done using standard guidelines. These were then self-administered to patients. The BASMI measurements, occiput-to-wall distance, chest expansion (in centimeters), total enthesis count, ESR, and C reactive protein (CRP) were measured. To assess reliability, the patient was called back on day 14, and the questionnaires were again self-administered, and the intra-class correlation coefficient was calculated to assess reliability. Correlation of questionnaire scores with acute phase reactants, measurements, and enthesitis index were used to assess for construct validity. Some modifications were done in the Bath indices and HAQ-S for cross-cultural adaptation. For validation, 41 patients of ankylosing spondylitis with a mean age of 34 years (±10.2) and disease duration of 5.8 years (±6.2) were included. The Bath Ankylosing Spondylitis Functional Index (BASFI), BASDAI, and HAQ-S showed good correlation among themselves (r = 0.69 to 0.84, p < 0.001), except for BAS-G with HAQ-S (r = 0.53, p < 0.001). Correlation between BASDAI and ESR (0.31, p = 0.05), CRP (0.48, p < 0.001), and enthesitis score (0.32, p = 0.045) was fair. Similarly, there was fair correlation of BASFI with ESR (0.55, p < 0.001), CRP (p = 0.60, p < 0.001), and various metrological measurements. These suggest convergent validity. However, there was a lack of correlation between metrological measurements and BASDAI, demonstrating divergent validity. The intra-class correlation coefficients between baseline and retest were acceptable: BASDAI intra-class correlation coefficients (ICC) 0.87 (0.78–0.93), BASFI ICC 0.90 (0.82–0.94), BAS-G ICC 0.75 (0.58–0.86), and HAQ-S ICC 0.91 (0.84–0.95). The Hindi versions of the BASDAI, BASFI, BAS-G, and HAQ-S were found to be valid and reliable for use in Hindi-speaking Indian patients with ankylosing spondylitis.