COPD: Classification System Misses the Mark

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) classifies patients with chronic obstructive pulmonary disease (COPD) into four groups, A-D. Joohae Kim of the Division of Pulmonary and Critical Care Medicine at Seoul National University College of Medicine, and colleagues evaluated lung function changes according to those four groups, and found that there was “no significant difference in lung function decline rates according to GOLD groups.” The study was published in the International Journal of Chronic Obstructive Pulmonary Disease on September 7, 2015.

The GOLD categories are based on symptoms and risks. Although several other studies had investigated the clinical outcomes according to GOLD group, only two other studies had focused on lung function decline before this one. The researchers performing this study expected to provide further information on the best uses of the GOLD classification system. The researchers used data from the Korean Obstructive Lung Disease (KOLD) study, which was a multicenter, prospective, longitudinal, cohort study.

There were a total of 175 patients included in this study, with 33.1% being classified in group A, 25.7% group B, 8,6% group C, and 32.6% in group D. The researchers did not find any significant difference in lung function decline between the four groups. Groups A and B are considered low risk groups, whereas C and D are high risk groups.

Although it may seem that lung function decline would be worse among those patients in the high risk groups C and D, the researchers offer several possible explanations for the similarity in decline across all four groups. For example, exacerbation history may play a role in lung function decline and there is no evidence that worse symptoms lead to a faster decline.

Despite some limitations, such as the fact that all of the participants were Korean and male, the researchers concluded that the GOLD group classification system could not predict lung function decline. They suggest that the older method of using postbronchodilator forced expiratory volume in one second is a better predictor of lung function decline.