Chronic Airways Assessment Test: psychometric properties in patients with asthma and/or COPD

BackgroundNo short patient-reported outcome (PRO) instruments assess overall health status across different obstructive lung diseases. Thus, the wording of the introduction to the Chronic Obstructive Pulmonary Disease (COPD) Assessment Test (CAT) was modified to permit use in asthma and/or COPD. This tool is called the Chronic Airways Assessment Test (CAAT).MethodsThe psychometric properties of the CAAT were evaluated using baseline data from the NOVELTY study (NCT02760329) in patients with physician-assigned asthma, asthma + COPD or COPD. Analyses included exploratory/confirmatory factor analyses, differential item functioning and analysis of construct validity. Responses to the CAAT and CAT were compared in patients with asthma + COPD and those with COPD.ResultsCAAT items were internally consistent (Cronbach's alpha: > 0.7) within each diagnostic group (n = 510). Models for structural and measurement invariance were strong. Tests of differential item functioning showed small differences between asthma and COPD in individual items, but these were not consistent in direction and had minimal overall impact on the total score. The CAAT and CAT were highly consistent when assessed in all NOVELTY patients who completed both (N = 277, Pearson's correlation coefficient: 0.90). Like the CAT itself, CAAT scores correlated moderately (0.4-0.7) to strongly (> 0.7) with other PRO measures and weakly (< 0.4) with spirometry measures.ConclusionsCAAT scores appear to reflect the same health impairment across asthma and COPD, making the CAAT an appropriate PRO instrument for patients with asthma and/or COPD. Its brevity makes it suitable for use in clinical studies and routine clinical practice.Trial registration: NCT02760329.Plain language summaryChronic Airways Assessment Test: a questionnaire adapted to assess overall health in asthma and/or COPDWhat is it about?Asthma and chronic obstructive pulmonary disease (COPD) can have a significant effect on a person's health and wellbeing. For people with these conditions, most of the health questionnaires available for use in patient care are designed for one specific diagnosis - either asthma (e.g. Asthma Control Test) or COPD (e.g. COPD Assessment Test [CAT]). A small number of questionnaires are available for use in both asthma and COPD, but these either take too long to complete, or do not focus on the overall health of patients. Since the symptoms in asthma and COPD overlap, a health questionnaire is needed for use in both asthma and COPD that can be completed during a routine visit to a doctor. This questionnaire could also help with research into the impact of lung diseases in people who have an unclear diagnosis.The CAT was changed so that people with asthma or COPD (or both) could use the same test. We named this new version the Chronic Airways Assessment Test (CAAT). Our goal was to determine whether CAAT scores meant the same level of health in people with asthma, COPD, or both conditions.The CAAT has eight questions, each scored 0 to 5, and takes only a few minutes to complete. The first three questions ask about the person's symptoms, including how often they cough and whether they have chest mucus or chest tightness. The remaining five questions ask how the person's asthma or COPD (or both) affects their daily life. These questions ask about shortness of breath, difficulties doing activities at home, confidence in leaving their home, whether they sleep soundly and how much energy they have.We found that the CAAT performed similarly in people with asthma or COPD (or both). This indicates that the CAAT score means a similar thing for someone with asthma, COPD or both conditions.Why is it important?The CAAT is a quick and simple way for patients to share with their doctor how bad their symptoms are and how much they affect their daily life. The development of the CAAT means that only one questionnaire is needed to measure the effect of a person's symptoms on their current level of health, whether they have asthma, COPD, or both. This will allow doctors to improve the level of care patients receive.