Deterioration and Mortality Risk of COPD Patients Not Fitting into Standard GOLD Categories : Results of the COSYCONET Cohort

Abstract

Background: Patients with COPD-specific symptoms and history but FEV1/FVC ratio ≥0.7 are a heterogeneous group (former GOLD grade 0) with uncertainties regarding natural history. Objective: We investigated which lung function measures and cutoff values are predictive for deterioration according to GOLD grades and all-cause mortality. Methods: We used visit 1–4 data of the COSYCONET cohort. Logistic and Cox regression analyses were used to identify relevant parameters. GOLD 0 patients were categorized according to whether they maintained grade 0 over the following 2 visits or deteriorated persistently into grades 1 or 2. Their clinical characteristics were compared with those of GOLD 1 and 2 patients. Results: Among 2,741 patients, 374 GOLD 0, 206 grade 1, and 962 grade 2 patients were identified. GOLD 0 patients were characterized by high symptom burden, comparable to grade 2, and a restrictive lung function pattern; those with FEV1/FVC above 0.75 were unlikely to deteriorate over time into grades 1 and 2, in contrast to those with values between 0.70 and 0.75. Regarding mortality risk in GOLD 0, FEV1%predicted and age were the relevant determinants, whereby a cutoff value of 65% was superior to that of 80% as proposed previously. Conclusions: Regarding patients of the former GOLD grade 0, we identified simple criteria for FEV1/FVC and FEV1% predicted that were relevant for the outcome in terms of deterioration over time and mortality. These criteria might help to identify patients with the typical risk profile of COPD among those not fulfilling spirometric COPD criteria.