Unravelling the Information Contained in the Single Items of the COPD Assessment Test for Different Outcomes and Smoking Status in Patients with COPD: Results from COSYCONET

Int J Chron Obstruct Pulmon Dis. 2024 Dec 5:19:2629-2638. doi: 10.2147/COPD.S475112. eCollection 2024.

Abstract

Background: The COPD Assessment Test (CAT) comprises eight questions. We evaluated the information that each of the questions and the total score contributed to outcomes and characteristics of chronic obstructive lung disease (COPD), including their dependence on smoking status.

Methods: Patients with COPD of the COSYCONET cohort with Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1-4 and the former grade 0 were included. The evaluated outcomes included mortality, exacerbation risk, the comorbidities asthma, cardiac disease (coronary artery disease/heart failure), osteoporosis, and emphysema, for which a reduction in carbon monoxide transfer coefficient (KCO) <55% predicted was considered as marker. Analyses were performed by Cox proportional hazard or logistic multiple regression analyses separately for smokers and nonsmokers.

Results: In total, 2509 patients had complete data, among them 1884 nonsmokers (ex or never; 38.4% female; mean age±SD 66.1±8.5 years) and 625 current smokers (45.1% female, 61.6±7.9 years). The pattern of responses to the single questions of the CAT differed between outcome variables, as well as between smokers and nonsmokers, but in most cases the total score was superior to the single items. The CAT total score was associated with mortality (p<0.05) only in nonsmokers, while for exacerbation frequency/severity, it was of about equal importance in smokers and nonsmokers. Regarding KCO, the total score was indicative (p<0.05) only in nonsmokers. Particularly in smokers, single items could show opposite signs of their coefficients which therefore largely cancelled in the total score.

Conclusion: Our results show in detail for which outcomes single items are informative in nonsmokers and current smokers with COPD, overall being more informative in nonsmokers. Only regarding exacerbation risk, the predictive value was similar in both groups. These results might be helpful to extract as much as possible information from a COPD questionnaire that is often part of routine assessment.

Trial registration: NCT01245933.

Keywords: COPD; COPD assessment test CAT; clinical questionnaire; exacerbation; mortality; smoking status.

Publication types

  • Multicenter Study
  • Observational Study
  • Comparative Study

MeSH terms

  • Aged
  • Comorbidity
  • Disease Progression
  • Ex-Smokers / statistics & numerical data
  • Female
  • Humans
  • Logistic Models
  • Lung* / physiopathology
  • Male
  • Middle Aged
  • Non-Smokers
  • Predictive Value of Tests
  • Prognosis
  • Proportional Hazards Models
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive* / diagnosis
  • Pulmonary Disease, Chronic Obstructive* / mortality
  • Pulmonary Disease, Chronic Obstructive* / physiopathology
  • Risk Assessment
  • Risk Factors
  • Severity of Illness Index
  • Smokers
  • Smoking* / adverse effects
  • Smoking* / epidemiology
  • Surveys and Questionnaires
  • Time Factors

Associated data

  • ClinicalTrials.gov/NCT01245933

Grants and funding

COSYCONET is supported by the German Federal Ministry of Education and Research (BMBF) Competence Network Asthma and COPD (ASCONET) and performed in collaboration with the German Center for Lung Research (DZL). The project is funded by the BMBF with grant number 01 GI 0881, and by DZL with grant-number 82DZLI05B2. It is furthermore supported by unrestricted grants from AstraZeneca GmbH, Bayer Schering Pharma AG, Boehringer Ingelheim Pharma GmbH & Co. KG, Chiesi GmbH, GlaxoSmithKline, Grifols Deutschland GmbH, MSD Sharp & Dohme GmbH, Mundipharma GmbH, Novartis Deutschland GmbH, Pfizer Pharma GmbH, Takeda Pharma Vertrieb GmbH & Co. KG, Teva GmbH for patient investigations and laboratory measurements. For the present study, an additional grant for data management was given by Novartis Pharma GmbH. The funding body had no involvement in the design of the study, or the collection, analysis or interpretation of the data.