Reanalysis of the Japanese experience using the combined COPD assessment of the 2011 GOLD classification

Abstract

Background: The Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2011 consensus report proposed a new classification system, incorporating symptoms with future risk, in subjects with chronic obstructive pulmonary disease (COPD). We hypothesized it could be applied to Japanese COPD patients.

Methods: We previously analyzed clinical factors related to 5-year mortality in 150 male outpatients with COPD. We reviewed the data and reanalyzed the relationships between the new GOLD classification and various outcomes including mortality.

Results: There were 51 (34.0%), 12 (8.0%), 57 (38.0%), and 30 (20.0%) patients in GOLD A (forced expiratory volume in 1s [FEV1] ≥ 50% predicted and modified Medical Research Council [mMRC] 0-1), GOLD B (FEV1 ≥ 50% predicted and mMRC ≥ 2), GOLD C (FEV1<50% predicted and mMRC 0-1), and GOLD D (FEV1 <50% predicted and mMRC ≥ 2), respectively. The GOLD 2011 classification correlated significantly with exercise capacity and multi-dimensional disease staging. Cox proportional hazards analysis revealed that, among several methods categorizing symptoms, the GOLD A-D classification was significantly associated with mortality (p=0.0055).

Conclusion: Although the relative number of patients in each category of the combined COPD assessment classification depended on the choice of symptom measures, the categories defined by the mMRC scale (score 0-1 versus ≥ 2) were most useful for future risk assessed as mortality. GOLD A had the lowest mortality, followed by GOLD B and C, and D had the highest mortality. Exercise capacity was also stratified by the new GOLD classification.

Keywords: COPD Assessment Test; Chronic obstructive pulmonary disease; Global Initiative for Chronic Obstructive Lung Disease; Mortality; St. George's Respiratory Questionnaire.