The impact on future risk of one moderate COPD exacerbation in GOLD A patients – a cohort study

Background: GOLD A patients are considered mild and with a low symptom burden. Therefore, our aim was to investigate the impact on future risk of a single moderate COPD exacerbation in GOLD A patients. Methods: Based on data from the Danish national registers, we included all patients ≥40 years with an ICD-10 J44 diagnosis (COPD Register, 2008-2014). Index was date of first registered modified Medical Research Council (mMRC) score 0-1; baseline period was 12 months pre-index. Patients were grouped as: A0, no exacerbation; and A1, one moderate exacerbation during baseline, and followed for one year for moderate exacerbations (defined as short-term course of prednisolone ± antibiotics), severe exacerbations (emergency visit or hospitalization) and death. Using A0 as reference, a Cox model estimated the hazard ratio for exacerbation (accounting for recurrent events). Multinominal logistic regression was used to estimate the odds ratio (OR) for exacerbation and death. Results: In total, 7,191 patients (mean (SD) age 65.6 (10.2) years, 53.1% male) were included, 3,958 GOLD A0 and 3,233 GOLD A1. During the 1-year follow-up, 59.6% (A0) and 44.9% (A1) had no exacerbation, 22.9% (A0) and 26.0% (A1) had one exacerbation, whereas 12.8% (A0) and 23.8% (A1) had a severe path with ≥2 moderate and/or ≥1severe exacerbation(s). In addition, 2.6% (A0) and 3.2% (A1) died. In A1, the OR for 1 moderate, ≥2 moderate and ≥1 severe exacerbation(s) was 1.50 [CI 1.33-1.68], 2.67 [2.30-3.11] and 1.88 [1.51-2.34] respectively, compared with A0 and the OR for death was 1.55 [1.16-2.10]. Conclusion: Even in GOLD A patients, one moderate exacerbation increases the odds of subsequent exacerbations and death significantly.