A Comparison of GOLD and STAR Severity Stages in Individuals with Chronic Obstructive Pulmonary Disease 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 chronic obstructive pulmonary disease (COPD). STUDY QUESTION What is the agreement and utility of the GOLD and STAR classifications in severe COPD patients 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 COPD patients undergoing pulmonary rehabilitation (PR). RESULTS A total of 1,516 participants (33.7% females, median age 72.0 years) were included in the analysis. Compared to GOLD, the use of the STAR classification resulted in a different disease severity category for 53.4% of patients. An unweighted Cohen's κ of 0.25 and a Bangdiwala B value of 0.24 revealed a fair agreement between the two classifications. Higher weighted agreement measures (0.47 and 0.78, respectively) suggested that discrepancies between the classifications mainly occurred for contiguous stages. GOLD demonstrated superior discrimination between stages for chronic respiratory failure, while STAR exhibited better performance in detecting hyperinflation. In terms of their application within PR settings, GOLD exhibited superior performance compared to STAR in identifying the minimal clinically important difference (MCID) in 6-minute walking distance and modified Medical Research Council (mMRC) score. Accordingly, GOLD but not STAR acted as an independent predictor for achieving a MCID in mMRC (OR: 1.48; 95% CI: 1.12-1.94; P=0.005) and also independently predicted changes in Braden score (β=0.154; P=0.004). INTERPRETATION STAR shows 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.