The Development and Initial Psychometric Testing of a Patient-Reported Outcome Measure to Assess COPD-Related Emotional Distress

Purpose: Emotional distress is prevalent in patients with COPD and highly relevant to patients. Research in chronic disease indicates that illness-related emotional distress might be specific and sensitive enough to explain self-management behaviour. However, as no currently available instrument assesses COPD-related emotional distress (CRED), it has only been assessed regarding overall distress, using mainly anxiety and depression as outcomes. Therefore, this study aimed to develop and test a preliminary item list to measure CRED. Patients and Methods: Following Food and Drug Administration (FDA) guidelines, a multistep mixed-method study was conducted. Based on an earlier qualitative study and literature review, a conceptual framework and item list were developed. The item list’s content validity was assessed via patient interviews using cognitive debriefing techniques and a survey involving a panel of clinicians. Finally, its psychometric properties were tested in a cross-sectional study. Construct validity was established by comparing the CRED-V1 with established questionnaires like the COPD Assessment Test (CAT), the Hospital Anxiety and Depression Scale (HADS), and the modified Medical Research Counsel (mMRC) dyspnoea scale. Results: The first German COPD-Related Emotional Distress questionnaire–version 1 (CRED–V1) contained 36 items. Its content validity was confirmed by nine patients and ten clinicians. Psychometric testing in 264 patients with COPD revealed two formative (symptom- and treatment-related) and four reflective (restricted mobility-, restricted relationship-, disease unpredictability- and stigma-related) subcategories. For all reflective subscales, Cronbach’s alpha values were > 0.8. Structural equation modelling was possible for 32 items: An R 2 value of 0.656 allowed the calculation of a CRED total score (CRED–TS). A regression model using the CRED-TS as the outcome variable showed that the most important explanatory variables were the CAT and HADS depression scores. Conclusion: This work reports the initial development of a new innovative tool for the assessment of CRED in patients with COPD.