COPD Mortality Predictions by GOLD 2017 vs Previous Versions

The new Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2017 classification does not predict all-cause and respiratory mortality in chronic obstructive pulmonary disease (COPD) more accurately than previous GOLD classification systems, according to a Danish study published in Lancet Respiratory Medicine.

Risk stratification of patients by COPD severity is an important clinical tool that provides the foundation for therapeutic recommendations. In contrast to earlier GOLD classification systems, the new GOLD 2017 classification separates the spirometric 1-4 staging from the ABCD groups, which are defined by symptoms and exacerbations.

Anne Gedebjerg, MD, from the Department of Clinical Epidemiology, Aarhus University Hospital in Denmark, and colleagues evaluated the predictive abilities of the new classification system in a nationwide cohort study that enrolled 33,765 hospital outpatients with COPD between January 1, 2008 and November 30, 2013.

Eligible patients were aged 30 years or older, had received a primary diagnosis of COPD or acute respiratory failure in combination with COPD as a secondary diagnosis, and had complete data on forced expiratory volume in 1 second, body mass index, modified Medical Research Council dyspnea scale score, and smoking status.  

The investigators categorized patients with complete data according to 2007, 2011, and 2017 classifications at the first contact with an outpatient clinic. They further subdivided patients by spirometry into 16 subgroups (1A to 4D) for the GOLD 2017 classification. For all groups and all 3 classifications, the investigators calculated adjusted hazard ratios (HRs) for all-cause and respiratory mortality and then compared the ability of the 3 GOLD classifications to predict mortality using receiver operating curves. 

Applying the GOLD 2017 classification, 3-year mortality rose with increasing exacerbations and dyspnea from group A (all-cause mortality, 10%; respiratory mortality, 3%) to group D (all-cause mortality, 36.9%; respiratory mortality, 18%). However, 3-year mortality was higher in group B than in group C patients (all-cause mortality, 23.8% vs 17.4% and respiratory mortality, 9.7% vs 6.4%, respectively). Compared with group A, adjusted HRs for all-cause mortality were 2.05 for group B, 1.47 for group C, and 3.01 for group D. Area under the curve (AUC) for all-cause mortality was 0.61 for GOLD 2007, 0.61 for GOLD 2011, and 0.63 for GOLD 2017. For respiratory mortality AUCs were 0.64, 0.63, and 0.65 for GOLD 2007, 2011, and 2017, respectively.

Although the GOLD 2017 classification based on ABCD groups only did not better predict mortality than earlier versions of GOLD classification, it did predict mortality more accurately than previous versions when the 16 subgroups were defined (P <.0001). 

Reference

Gedebjerg A, Szepligeti ZK, Holm Wackerhausen L-M, et al. Prediction of mortality in patients with chronic obstructive pulmonary disease with the new Global Initiative for Chronic Obstructive Lung Disease 2017 classification: a cohort study [published online January 10, 2018]. Lancet Respir Med. doi:10.1016/S2213-2600(18)30002-X