Is it time to rethink disability assessment in low back pain? Reliability, internal consistency, and construct validity of the Brazilian WHODAS 2.0 for chronic low back pain

Background and Purpose: The World Health Disability Assessment Schedule 2.0 (WHODAS 2.0) was developed to assess health and disability based on the biopsychosocial model. The WHODAS 2.0 has not been validated for Brazilians with chronic non- specific low back pain (LBP). We aimed to evaluate the reliability, internal consistency, and construct validity of the Brazilian version of the WHODAS 2.0 in patients with chronic LBP. Methods: Methodological study. The Brazilian version of the WHODAS 2.0 was applied to 100 volunteers with chronic nonspecific LBP. Test-retest reliability, internal consistency, and construct validity were assessed using the Spearman correlation test, Cronbach's alpha (a) coefficient, and Spearman's correlation test between WHODAS 2.0, the Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ), and Fear Avoidance Beliefs Questionnaire (FABQ), respectively. Results: WHODAS 2.0 showed satisfactory test-retest reliability with a moderate correlation for total WHODAS 2.0 (r = 0.75, p < 0.05). Internal consistency was adequate for all domains and total score (a = 0.82-0.96). Regarding construct validity, WHODAS 2.0, ODI (r = 0.70, p < 0.05), and WHODAS 2.0 and RMDQ (r = 0.71, p < 0.05) had significant correlations. Total WHODAS 2.0 and FABQ-Phys subscale scores correlated moderately (r = 0.66, p < 0.05). Discussion: The Brazilian WHODAS 2.0 was proved to be a valid and reliable tool for patients with chronic LBP. The item referring to sexual intercourse had 27% and 30% of the missing values during the test and retest stage, respectively and had a high percentage of missing data for work- related questions (41% missing data) in the life activities domain; therefore, the data must be interpreted with caution. Implications for Physiotherapy Practice: WHODAS 2.0 can be used as a disability assessment strategy from a biopsychosocial perspective in this population.