Translating and Validating a Hindi Version of the Spine Functional Index: Cross-cultural Adaptation and Psychometric Testing in an Indian Orthopedic Population.

INTRODUCTION

Existing Hindi patient-reported measures for spinal disorders assess the cervical and lumbar spine separately. The spine functional index (SFI) evaluates whole-spine functional limitation using 25 items, with validated Spanish, Turkish, and Chinese versions, but not Hindi. This study aimed to translate and culturally adapt the SFI into Hindi (SFI-Hi) and evaluate its measurement properties, including responsiveness and the minimal clinically important difference (MCID), in Indian patients with spinal disorders.

MATERIALS AND

METHODS

The SFI was translated and culturally adapted using forward-backward translation, expert review, and pilot testing. One hundred eighty-six consecutive adults with chronic (≥12 weeks) cervical, lumbar, or combined spinal disorders completed the SFI-Hi, Hindi functional rating index (FRI-Hi), Hindi SF-12, and a pain visual analog scale (VAS); cervical patients also completed the Hindi neck disability index (NDI-Hi), and lumbar patients the Hindi Oswestry disability index (ODI-Hi). Ninety stable participants repeated the SFI-Hi after 5-7 days, and 92 treated patients were reassessed at 6 weeks for responsiveness and MCID. Internal consistency, test-retest reliability, measurement error, construct validity, principal component analysis (PCA), responsiveness, MCID, and floor/ceiling effects were assessed.

RESULT: Mean SFI-Hi score was 49.0 ± 16.6 on a 0-100 disability scale. Internal consistency was high (Cronbach's α = 0.92), and test-retest reliability was excellent (ICC2,1 = 0.96, 95% CI 0.94-0.98), with a standard error of measurement of 2.8% and minimal detectable change of 6.5%. PCA identified a single dominant component explaining 35.0% of variance. Correlations were observed with the ODI-Hi (r = 0.64), FRI-Hi (r = 0.56), NDI-Hi (r = 0.53), VAS (r = 0.46), and SF-12 physical functioning (r = -0.54); only three of six prespecified hypotheses were confirmed. The SFI-Hi demonstrated good responsiveness (standardized response mean 0.84), with a 13.2-point improvement at 6 weeks (P < 0.001); the anchor-based MCID was 8 points (AUC 0.81). No clinically important floor or ceiling effect was observed. I was observed.

CONCLUSION

The SFI-Hi demonstrated high internal consistency, excellent test-retest reliability, good responsiveness, and a predominantly unidimensional structure in this Indian cohort, with partial support for construct validity. It is a promising whole-spine outcome measure for Hindi-speaking patients, warranting further evaluation in larger, more diverse populations.