A pooled analysis of 15,632 COPD patients comparing the GOLD 2007 and 2011 staging systems for COPD focused on mortality

Background There is no universal consensus on the best staging system for chronic obstructive pulmonary disease(COPD). Although documents (eg, the Global Initiative for Chronic Obstructive Lung Disease [GOLD] 2007) havetraditionally used forced expiratory volume in 1 s (FEV1) for staging, clinical parameters have been added to someguidelines (eg, GOLD 2011) to improve patient management. As part of the COPD Cohorts Collaborative InternationalAssessment (3CIA) initiative, we aimed to investigate how individual patients were categorised by GOLD 2007 and2011, and compare the prognostic accuracy of the staging documents for mortality.Methods We searched reports published from Jan 1, 2008, to Dec 31, 2014. Using data from cohorts that agreed toparticipate and had a minimum amount of information needed for GOLD 2007 and 2011, we did a patient-basedpooled analysis of existing data. With use of raw data, we recalculated all participant assignments to GOLD 2007 I–IVclasses, and GOLD 2011 A–D stages. We used survival analysis, C statistics, and non-parametric regression to modeltime-to-death data and compare GOLD 2007 and GOLD 2011 staging systems to predict mortality.Findings We collected individual data for 15 632 patients from 22 COPD cohorts from seven countries, totalling70 184 person-years. Mean age of the patients was 63·9 years (SD 10·1); 10 751 (69%) were men. Based on FEV1 alone(GOLD 2007), 2424 (16%) patients had mild (I), 7142 (46%) moderate (II), 4346 (28%) severe (III), and 1670 (11%) verysevere (IV) disease. We compared staging with the GOLD 2007 document with that of the new GOLD 2011 system in14 660 patients: 5548 (38%) were grade A, 2733 (19%) were grade B, 1835 (13%) were grade C, and 4544 (31%) weregrade D. GOLD 2011 shifted the overall COPD severity distribution to more severe categories. There were nearly threetimes more COPD patients in stage D than in former stage IV (p<0·05). The predictive capacity for survival up to10 years was signifi cant for both systems (p<0·01) but area under the curves were only 0·623 (GOLD 2007) and 0·634(GOLD 2011), and GOLD 2007 and 2011 did not diff er signifi cantly. We identifi ed the percent predicted FEV1thresholds of 85%, 55% and 35% as better to stage COPD severity for mortality, which are similar to the ones usedpreviously.Interpretation Neither GOLD COPD classifi cation schemes have suffi cient discriminatory power to be used clinicallyfor risk classifi cation at the individual level to predict total mortality for 3 years of follow-up and onwards. Increasingintensity of treatment of patients with COPD due to their GOLD 2011 reclassifi cation is not known to improve healthoutcomes. Evidence-based thresholds should be searched when exploring the prognostic ability of current and newCOPD multicomponent indices.