Validating the Persian version of the amyotrophic lateral sclerosis-specific quality of life-revised instrument

Background: Amyotrophic Lateral Sclerosis-Specific Quality of Life-Revised (ALSSQOL-R) encompasses 50 items which assess quality of life (QOL) in patients with amyotrophic lateral sclerosis (ALS) in six major domains. This study aims to translate the ALSSQOL-R into Persian and evaluate its reliability and validity among Iranian patients. Methods: ALSSQOL-R was translated by the standard multi-step forward-backward method. Content validity was calculated using item content validity index (I-CVI). Three items in the “intimacy” domain were deleted considering Iranian culture. Cronbach’s alpha was used for all 6 dimensions to calculate the internal consistency reliability. Test-retest reliability was evaluated using intraclass correlation coefficient (ICC) with one-month interval. Concurrent validity was measured by the validated version of 36-Item Short Form Health Survey (SF-36) questionnaire. Results: Sixty-three patients with ALS were enrolled in the study. I-CVI was 70%, promoted to 85% after modifications (acceptable). Regarding internal consistency reliability, Cronbach’s alpha in all six domains was ≥ 0.70 and total Cronbach’s alpha was 0.89 which is assumed as good. In terms of test-retest reliability, ICC [95% confidence interval (CI)] was 0.91 (91%) and Pearson correlation coefficient (r) was 0.90 (P 0.001), all indicating an excellent reliability. The concurrent validity was established based on a strong correlation with SF-36 (r = 0.744, P 0.001). Conclusion: The findings show that the modified Persian version of ALSSQOL-R is a valid and reliable QOL questionnaire which can be used for Iranian patients with ALS in both clinical and research settings.