Clinical impacts of the classification by 2017 GOLD guideline comparing previous ones on outcomes of COPD in real-world cohorts

PURPOSE: While GOLD classification has been revised, its clinical impacts on outcomes of COPD patients have not been widely evaluated in real-world cohorts. MATERIALS AND METHODS: According to 2007, 2013, and 2017 GOLD classifications, distribution and clinical characteristics of group-shifted patients and the risk of acute exacerbation were analyzed in combined Korean COPD cohorts. Future risk for annual moderate-to-severe exacerbation was estimated as incidence rate ratio (IRR) and compared by groups. RESULTS: Among 1,880 COPD patients, in GOLD 2017 classification, groups B and A were increased to 61.2% and 22.2% of total population, while group C was shrunken to 2.2% and patients with higher risk were decreased (16.6% in GOLD 2017 vs 44.7% in GOLD 2013). The kappa coefficient of agreement of both systems was 0.581 (agreement 71.7%). Groups B and D showed higher IRR of moderate-to-severe exacerbation than group A (IRR 2.4 and 5.3 respectively, P<0.001), whereas group C was not different from group A. When groups C and D were combined, the IRR for acute exacerbation for each group showed good linear trends (2.5 [1.6–3.7] for group B and 4.8 [3.0–7.7] for combined group [C+D], P<0.001). CONCLUSIONS: In the revised GOLD 2017 system, COPD patients with higher risk were much decreased in Korean cohorts, and group C was negligible in size and clinical impacts on expecting future exacerbation. Serial increase in the risk for exacerbation was more concrete and predictable when group C was combined with group D.