Health and Quality of Life Outcomes (May 2010)

Validation of the "World Health Organization Disability Assessment Schedule, WHODAS-2" in patients with chronic diseases

  • Burger Helena,
  • Svetskova Olga,
  • Cieza Alarcos,
  • Alonso Jordi,
  • Vilagut Gemma,
  • Chatterji Somnath,
  • Nieto Marta,
  • Almansa Josué,
  • Ayuso-Mateos Jose,
  • Garin Olatz,
  • Racca Vittorio,
  • Francescutti Carlo,
  • Vieta Eduard,
  • Kostanjsek Nenad,
  • Raggi Alberto,
  • Leonardi Matilde,
  • Ferrer Montse

DOI
https://doi.org/10.1186/1477-7525-8-51
Journal volume & issue
Vol. 8, no. 1
p. 51

Abstract

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Abstract Background The WHODAS-2 is a disability assessment instrument based on the conceptual framework of the International Classification of Functioning, Disability, and Health (ICF). It provides a global measure of disability and 7 domain-specific scores. The aim of this study was to assess WHODAS-2 conceptual model and metric properties in a set of chronic and prevalent clinical conditions accounting for a wide scope of disability in Europe. Methods 1,119 patients with one of 13 chronic conditions were recruited in 7 European centres. Participants were clinically evaluated and administered the WHODAS-2 and the SF-36 at baseline, 6 weeks and 3 months of follow-up. The latent structure was explored and confirmed by factor analysis (FA). Reliability was assessed in terms of internal consistency (Cronbach's alpha) and reproducibility (intra-class correlation coefficients, ICC). Construct validity was evaluated by correlating the WHODAS-2 and SF-36 domains, and comparing known groups based on the clinical-severity and work status. Effect size (ES) coefficient was used to assess responsiveness. To assess reproducibility and responsiveness, subsamples of stable (at 6 weeks) and improved (after 3 moths) patients were defined, respectively, according to changes in their clinical-severity. Results The satisfactory FA goodness of fit indexes confirmed a second order factor structure with 7 dimensions, and a global score for the WHODAS-2. Cronbach's alpha ranged from 0.77 (self care) to 0.98 (life activities: work or school), and the ICC was lower, but achieved the recommended standard of 0.7 for four domains. Correlations between global WHODAS-2 score and the different domains of the SF-36 ranged from -0.29 to -0.65. Most of the WHODAS-2 scores showed statistically significant differences among clinical-severity groups for all pathologies, and between working patients and those not working due to ill health (p Conclusions The latent structure originally designed by WHODAS-2 developers has been confirmed for the first time, and it has shown good metric properties in clinic and rehabilitation samples. Therefore, considerable support is provided to the WHODAS-2 utilization as an international instrument to measure disability based on the ICF model.