Disability related to COPD tool (DIRECT): towards an assessment of COPD-related disability in routine practice

Abstract

Background

Chronic Obstructive Pulmonary Disease (COPD) is a worldwide public health concern. It is also a major source of disability that is often overlooked, depriving patients of effective treatments. This study describes the development and validation of a questionnaire specifically assessing COPD-related disability.

Methods

The DIsability RElated to COPD Tool (DIRECT) was developed according to reference methods, including literature review, patient and clinician interviews and test in a pilot study. A 12-item questionnaire was included for finalization and validation in an observational cross-sectional study conducted by 60 French pulmonologists, who recruited 275 COPD patients of stage II, III and IV according to the GOLD classification. Rasch modeling was conducted and psychometric properties were assessed (internal consistency reliability; concurrent and clinical validity).

Results

The DIRECT score was built from the 10 items retained in the Rasch model. Their internal consistency reliability was excellent (Cronbach’s alpha = 0.95). The score was highly correlated with the Saint George’s Respiratory Questionnaire Activity score (r = 0.83) and the London Handicap Scale (r = −0.70), a generic disability measure. It was highly statistically significantly associated to four clinical parameters ( P < 0.001): GOLD classification, BODE index, FEV ₁ and 6-minute walk distance.

Conclusion

DIRECT is a promising tool that could help enhance the management of COPD patients by integrating an evaluation of the COPD-related disability into daily practice.