A Comparison of GOLD and STAR Severity Stages in Individuals With COPD Undergoing Pulmonary Rehabilitation.

BACKGROUND

Alongside the recognized Global Initiative for Obstructive Lung Disease (GOLD) classification, the Staging of Airflow Obstruction by Ratio (STAR) severity scheme has been proposed for categorizing COPD.

STUDY QUESTION

What are the agreement and utility of the GOLD and STAR classifications in patients with severe COPD entering the rehabilitation setting?

STUDY DESIGN AND METHODS

Medical records were reviewed in this multicenter retrospective study, examining key functional variables and their changes in a large cohort of patients with COPD undergoing pulmonary rehabilitation.

RESULTS

A total of 1,516 participants (33.7% female participants; median age, 72.0 years) were included in the analysis. Compared with GOLD, the use of the STAR classification resulted in a different disease severity category for 53.4% of patients. An unweighted Cohen's kappa of 0.25 and a Bangdiwala B value of 0.24 indicated a fair agreement between the 2 classifications. Higher weighted agreement measures (0.47 and 0.78, respectively) suggested that discrepancies between the classifications mainly occurred for contiguous stages. GOLD exhibited superior discrimination between stages for chronic respiratory failure, whereas STAR exhibited better performance in detecting hyperinflation. In terms of their application within pulmonary rehabilitation settings, GOLD exhibited superior performance compared with STAR in identifying the minimal clinically important difference in 6-min walking distance and modified Medical Research Council score. Accordingly, GOLD but not STAR acted as an independent predictor for achieving a minimal clinically important difference in modified Medical Research Council score (OR, 1.48; 95% CI, 1.12-1.94; P = .005) and also independently predicted changes in the Braden scale score (β = 0.154; P = .004).

INTERPRETATION

STAR exhibited a more uniform gradation of disease severity and enhanced performance in detecting hyperinflation, but our preliminary findings do not endorse its utilization in the rehabilitation setting.