Finding the Best Thresholds of FEV(1) and Dyspnea to Predict 5-Year Survival in COPD Patients: The COCOMICS Study

BACKGROUND: FEV(1) is universally used as a measure of severity in COPD. Current thresholds are based on expert opinion and not on evidence. OBJECTIVES: We aimed to identify the best FEV(1) (% predicted) and dyspnea (mMRC) thresholds to predict 5-yr survival in COPD patients. DESIGN AND METHODS: We conducted a patient-based pooled analysis of eleven COPD Spanish cohorts (COCOMICS). Survival analysis, ROC curves, and C-statistics were used to identify and compare the best FEV(1) (%) and mMRC scale thresholds that predict 5-yr survival. RESULTS: A total of 3,633 patients (93% men), totaling 15,878 person-yrs. were included, with a mean age 66.4±9.7, and predicted FEV(1) of 53.8% (±19.4%). Overall 975 (28.1%) patients died at 5 years. The best thresholds that spirometrically split the COPD population were: mild ≥70%, moderate 56–69%, severe 36–55%, and very severe ≤35%. Survival at 5 years was 0.89 for patients with FEV(1)≥70 vs. 0.46 in patients with FEV(1) ≤35% (H.R: 6; 95% C.I.: 4.69–7.74). The new classification predicts mortality significantly better than dyspnea (mMRC) or FEV(1) GOLD and BODE cutoffs (all p<0.001). Prognostic reliability is maintained at 1, 3, 5, and 10 years. In younger patients, survival was similar for FEV(1) (%) values between 70% and 100%, whereas in the elderly the relationship between FEV(1) (%) and mortality was inversely linear. CONCLUSIONS: The best thresholds for 5-yr survival were obtained stratifying FEV(1) (%) by ≥70%, 56–69%, 36–55%, and ≤35%. These cutoffs significantly better predict mortality than mMRC or FEV(1) (%) GOLD and BODE cutoffs.