Mortality and Exacerbations by Global Initiative for Chronic Obstructive Lung Disease Groups ABCD: 2011 Versus 2017 in the COPDGene® Cohort

Background: The Global initiative for chronic Obstructive Lung Disease (GOLD) ABCD groupings were recently modified. The GOLD 2011 guidelines defined increased risk as forced expiratory volume in 1 second (FEV1) < 50% predicted or >= 2 outpatient or >= 1 hospitalized exacerbation in the prior year, whereas the GOLD 2017 guidelines use only exacerbation history. We compared mortality and exacerbation rates in the Genetic Epidemiology of COPD Study cohort (COPDGene (R)) by 2011 (exacerbation history/FEV1 and dyspnea) versus 2017 (exacerbations and dyspnea) classifications. Methods: Using data from COPDGene (R), we tested associations of ABCD groups with all-cause mortality (Cox models, adjusted for age, sex, race and comorbidities) and longitudinal exacerbations (zero-inflated Poisson models). Results: In 4469 individuals (mean age 63.1 years, 44% female), individual distributions in 2011 versus 2017 systems were: A, 32.0% versus 37.0% B, 17.6% versus 36.3% C, 9.4% versus 4.4% D, 41.0% versus 22.3% (observed agreement 76% [expected 27.8%], Kappa 0.67, p<0.001). Individuals in group D-2011 had 1.1 +/- 1.6 exacerbations/year (mean +/- standard deviation [SD]) versus 1.4 +/- 1.8 for D-2017 (median follow-up 3.7 years). Using group A as reference, for both systems, mortality (median follow-up 6.8 years) was highest in group D (D-2011, [hazard ratio] HR 5.2 [95% confidence interval (CI) 4.2, 6.4]; D-2017, HR 5.5 [4.5, 6.8]), lowest for group C (HR 1.9 [1.4, 2.6] versus HR 1.9 [1.3, 2.8]) and intermediate for group B (HR 2.6 [2.0, 3.4] versus HR 3.4 [2.8, 4.1]). GOLD 2011 had better mortality discrimination (area under the curve [AUC] 0.68) than GOLD 2017 (AUC 0.66, p<0.001 for comparison) but similar exacerbation rate prediction. Conclusions: Relative to the GOLD 2011 consensus statement, discriminate predictive power of the 2017 ABCD classification is similar for exacerbations but lower for survival.