Introduction: Many patients with chronic obstructive pulmonary disease (COPD) do not report exacerbations and may benefit from simple guidance about when to seek medical attention, so we developed a COPD Exacerbation Recognition Tool (CERT).
Methods: The study was run across three sites in China in patients who had an exacerbation within the previous year. Step 1: focus group qualitative study (total 48 patients) captured symptoms associated with an exacerbation. Step 2: cognitive debriefing to ensure items were appropriately worded. Step 3: 150 patients (69 years, 21% female, FEV₁ 63% predicted, CAT 15, 2 exacerbations in previous year) completed a questionnaire composed of the items from Steps 1 and 2 using two response options – severity during an exacerbation and magnitude of change from usual state. Responses were analysed in terms of frequency and tested for influence of demographic factors. Exploratory factor analysis (EFA) identified key domains. Using these results, an expert panel guided choice of items that formed the CERT.
Results: Following Steps 1 and 2, 29 candidate items were selected for Step 3. Response rates with the two response options were very similar. There was minimal influence of demographic factors on response to the items. EFA using the 11 items with the highest response rates identified two principal factors, Factor 1: breathlessness and activity limitation (79.1% of variance), Factor 2: cough and sputum (20.9% of variance). Five items were selected for the CERT based on response rate and EFA factor loading: worsening cough, increased sputum volume, shortness of breath, laborious breathing, and limitation of motion. Sensitivity analysis suggested that worsening of two or more symptoms had good sensitivity and specificity for the presence of an exacerbation.
Discussion: The CERT is an evidence-based tool to provide patients with simple-to-follow guidance about when to seek medical attention when their COPD symptoms worsen.
Keywords: chronic obstructive pulmonary disease, exacerbations, COPD exacerbation tool