Lung function decline rates according to gold group in patients with chronic obstructive pulmonary disease

Background: Since the Global Initiative for Chronic Obstructive Lung Disease (GOLD) groups A-D were introduced, the lung function changes according to group have been evaluated rarely. Objective: We investigated the rate of decline in annual lung function in patients categorized according to the 2014 GOLD guidelines. Methods: Patients with COPD included in the Korean Obstructive Lung Disease (KOLD) prospective study, who underwent yearly postbronchodilator spirometry at least three times, were included. The main outcome was the annual decline in postbronchodilator forced expiratory volume in 1 second (FEV1), which was analyzed by random-slope and random-intercept mixed linear regression. Results: A total 175 participants were included. No significant postbronchodilator FEV1 decline was observed between the groups (-34.4±7.9 [group A]; -26.2±9.4 [group B]; -22.7±16.0 [group C]; and -24.0±8.7 mL/year [group D]) (P=0.79). The group with less symptoms (-32.3±7.2 vs -25.0±6.5 mL/year) (P=0.44) and the low risk group (-31.0±6.1 vs -23.6±7.7 mL/year) (P=0.44) at baseline showed a more rapid decline in the postbronchodilator FEV1, but the trends were not statistically significant. However, GOLD stages classified by FEV1 were significantly related to the annual lung function decline. Conclusion: There was no significant difference in lung function decline rates according to the GOLD groups. Prior classification using postbronchodilator FEV1 predicts decline in lung function better than does the new classification.