WHODAS 2.0 to Assess Disability in the Rehabilitation of Individuals With Chronic Respiratory Conditions: Responsiveness and Interpretability.

Only 33 people took part, all from one rehabilitation unit in Brazil, and most had COPD, so the results may not hold for other respiratory conditions or other settings. There was no control group. People were measured before and after the same programme, so the improvement could come from the programme, from getting better anyway, or from being assessed twice. The seven people who dropped out or could not follow the programme were left out of the analysis, which tends to make the results look better than they are. The 12-item version of WHODAS 2.0 gives only one overall score, so it cannot show which areas of life improved, such as mobility versus self-care or participation. Everyone had to be able to walk and take part in exercise training to join, so the findings do not apply to people who are housebound or acutely unwell. The correlation between the change in WHODAS score and the change in SGRQ score was only fair, so the two questionnaires are not measuring quite the same thing. The estimate of the smallest noticeable change comes from a small sample, and the confidence interval around the change reported by those who felt better crosses zero.

The research received no specific grant from public, commercial or not-for-profit funders. One author held a Master of Science scholarship from the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (FUNCAP) and from CAPES. The authors declare no conflicts of interest. There is no statement that a funder designed the study, analysed the data or wrote the manuscript.

Do not read the fall in disability scores as proof that this exercise programme works. There was no control group, so the improvement may reflect the programme, natural recovery or simply being assessed twice, and the people who dropped out or could not keep up were excluded from the analysis. The study was testing whether the WHODAS 2.0 questionnaire can detect change, and that is all it shows.