Predictors of COPD exacerbations differ between grades of airflow limitation

Background History of exacerbations is a predictor of future exacerbations in COPD but there are also predictors that are independent of exacerbation history. However, it is unclear whether their relative contribution is consistent across different degrees of airflow limitation. Methods This analysis used data from COMPASS, a prospective study in COPD. Baseline demographics, clinical history, spirometry, and patient-reported outcomes were collected. Multivariable models were created to predict moderate or severe exacerbations in the 18 months after baseline. Covariates included FEV 1 % predicted, GOLD grade, mMRC and CAT scores, and exacerbation history. Goodness of fit was tested using C-statistics. Results At baseline there were 1696 patients; 89.6% males, 46.9% current smokers, mean age 65.4±7.5( sd ), post-bronchodilator FEV 1 66.6±20.1% predicted, and 0.5±1.0 moderate/severe exacerbations in the prior year. Over 18 months, 17.8% of patients had ≥1 moderate/severe exacerbation. The best fit model identified six independent variables, C-statistic 0.739. Subgroup analysis into GOLD grades I, II and III+IV combined showed different predictor patterns. In grade I, history of moderate exacerbations was the strongest predictor, together with chronic bronchitis and gastroesophageal reflux. In grades III+IV, only history of severe exacerbations and mMRC score were significant. Grade II showed an intermediate picture in which severe exacerbations, chronic bronchitis and gastroesophageal reflux were all significant. Conclusions There are multiple predictors of COPD exacerbations, that differ between GOLD grades. Future predictive models for exacerbation risk should take this into account for this.