A score to predict short-term risk of COPD exacerbations (SCOPEX)

Background: There is no clinically useful score to predict chronic obstructive pulmonary disease (COPD) exacerbations. We aimed to derive this by analyzing data from three existing COPD clinical trials of budesonide/formoterol, formoterol, or placebo in patients with moderate-tovery- severe COPD and a history of exacerbations in the previous year. Methods: Predictive variables were selected using Cox regression for time to first severe COPD exacerbation. We determined absolute risk estimates for an exacerbation by identifying variables in a binomial model, adjusting for observation time, study, and treatment. The model was further reduced to clinically useful variables and the final regression coefficients scaled to obtain risk scores of 0-100 to predict an exacerbation within 6 months. Receiver operating characteristic (ROC) curves and the corresponding C-index were used to investigate the discriminatory properties of predictive variables. Results: The best predictors of an exacerbation in the next 6 months were more COPD maintenance medications prior to the trial, higher mean daily reliever use, more exacerbations during the previous year, lower forced expiratory volume in 1 second/forced vital capacity ratio, and female sex. Using these risk variables, we developed a score to predict short-term (6-month) risk of COPD exacerbations (SCOPEX). Budesonide/formoterol reduced future exacerbation risk more than formoterol or as-needed short-acting beta(2)-agonist (salbutamol). Conclusion: SCOPEX incorporates easily identifiable patient characteristics and can be readily applied in clinical practice to target therapy to reduce COPD exacerbations in patients at the highest risk.