Research in context
Evidence before this study
COPD affects many people worldwide, but its definition and staging remain controversial. Before 2011, the GOLD classification scheme was based exclusively on forced expiratory volume in 1 s (FEV1) thresholds. The 2011 GOLD document proposed a new classification scheme based on spirometry, the history of exacerbations, and symptoms. Since the publication of that document, several reports have compared it with the old 2007 grading, with somewhat conflicting results.
Added value of this study
We obtained and pooled individualised data from 22 published COPD cohorts, totalling 15 632 patients that contributed 70 184 person-years of follow-up to the study. The most important finding was that the 2011 GOLD classification scheme did not improve the prediction of mortality, as compared to the 2007 classification. Through the large size of the sample, we were able to overcome many of the limitations of individual studies, and had a large statistical power for most subanalyses. Therefore, we conclude that the more complicated GOLD 2011 classification scheme is no better than the simpler previous one based on spirometry only. The use of the 2011 staging system resulted in many more patients with the most severe disease (more in GOLD D than in GOLD IV), making them seem more ill. Further, GOLD class C might be superfluous because patients in this category have a similar mortality as those in class B and treatment strategies do not differ between the two groups.
Implications of all the available evidence
Neither GOLD COPD classification schemes had sufficient discriminatory power to be used clinically for risk-classification at the individual level to predict total mortality for 3 years of follow-up and up to 10 years. It is yet to be established if an increased intensity of treatment of patients with COPD by their GOLD 2011 reclassification improves their health outcomes.