Development and validation of the Capacity of Daily Living during the Morning questionnaire and the Global Chest Symptoms Questionnaire in COPD

This report concerns the development and validation of two patient-reported outcomes questionnaires developed to assess chronic obstructive pulmonary disease (COPD) patients' ability to perform morning activities and to evaluate their morning symptoms. Based on interviews with COPD patients, the Capacity of Daily Living during the Morning (CDLM) questionnaire and the Global Chest Symptoms Questionnaire (GCSQ) were developed, linguistically validated and incorporated into two multicentre, randomised trials involving a total of 1,100 COPD patients; those trials were registered at ClinicalTrials. gov (NCT00496470 and NCT00542880). Data from these trials were used to determine the reliability, validity and responsiveness of the questionnaires and to derive estimates of minimal important differences (MIDs). Both questionnaires displayed good-to-high reliability (Cronbach's a 0.75-0.93). Analysis of convergent validity showed that CDLM and GCSQ scores correlated significantly (p, 0.001) with symptoms, health-related quality of life (HRQoL) and use of rescue medication. In both trials, CDLM and GCSQ scores discriminated between patients with different levels of HRQoL, as assessed by the St George's Respiratory Questionnaire for COPD patients (SGRQ-C), but not with disease severity, as assessed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. A significant improvement in CDLM and GCSQ scores occurred in response to treatment. Estimations of MID scores, corresponding to an SGRQ-C MID of 4, were 0.20 for the CDLM questionnaire and 0.15 for the GCSQ. Both the CDLM questionnaire and the GCSQ are easy-to-use, reliable, responsive, selfadministered questionnaires that report on patients' symptoms and ability to perform morning activities.