Discrepancies between modified Medical Research Council dyspnea score and COPD assessment test score in patients with COPD.

Abstract

Background and objectiveAccording to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, either a modified Medical Research Council (mMRC) dyspnea score of ≥2 or a chronic obstructive pulmonary disease (COPD) assessment test (CAT) score of ≥10 is considered to represent COPD patients who are more symptomatic. We aimed to identify the ideal CAT score that exhibits minimal discrepancy with the mMRC score.MethodsA receiver operating characteristic curve of the CAT score was generated for an mMRC scores of 1 and 2. A concordance analysis was applied to quantify the association between the frequencies of patients categorized into GOLD groups A–D using symptom cutoff points. A κ-coefficient was calculated.ResultsFor an mMRC score of 2, a CAT score of 15 showed the maximum value of Youden’s index with a sensitivity and specificity of 0.70 and 0.66, respectively (area under the receiver operating characteristic curve [AUC] 0.74; 95% confidence interval [CI], 0.70–0.77). For an mMRC score of 1, a CAT score of 10 showed the maximum value of Youden’s index with a sensitivity and specificity of 0.77 and 0.65, respectively (AUC 0.77; 95% CI, 0.72–0.83). The κ value for concordance was highest between an mMRC score of 1 and a CAT score of 10 (0.66), followed by an mMRC score of 2 and a CAT score of 15 (0.56), an mMRC score of 2 and a CAT score of 10 (0.47), and an mMRC score of 1 and a CAT score of 15 (0.43).ConclusionA CAT score of 10 was most concordant with an mMRC score of 1 when classifying patients with COPD into GOLD groups A–D. However, a discrepancy remains between the CAT and mMRC scoring systems.