Pharmacological treatment response according to the severity of symptoms in patients with chronic obstructive pulmonary disease

Background: Pharmacological management of chronic obstructive pulmonary disease (COPD) is recommended according to the individualized assessment of symptoms and exacerbation risks. The aim of this study was to determine the relationship between the baseline Modified British Medical Research Council (mMRC) dyspnea scale and the COPD Assessment Test (CAT) score and pharmacological treatment response in patients with COPD. Methods: A total of 102 stable COPD patients who were enrolled in prospective cohort studies were analyzed. Pharmacological treatment responses after a 3-month treatment were assessed by changes on the mMRC dyspnea scale, CAT scores, and spirometric pulmonary functions. Results: Sixty-two patients with a mMRC dyspnea scale <= 1 were classified as having "less dyspnea" and 40 patients with a mMRC dyspnea scale >= 2 as having "more dyspnea". After a 3-month treatment, the mean mMRC dyspnea scale in the "more dyspnea" group was significantly decreased versus the " less dyspnea" group; however, there were no significant differences in CAT score changes or spirometric pulmonary function changes between the two groups. Baseline mMRC scales (Spearman's rho =-0.591, P<0.001) and baseline CAT scores (Pearson's r =-0.337, P=0.001) were significantly correlated with their changes after a 3-month treatment. Multiple logistic regression analysis demonstrated that baseline mMRC scale and CAT score were the only independent predictors of improvement greater than a minimal clinically significant difference after treatment. Conclusions: The severity of COPD symptoms is associated with their response to pharmacotherapy. COPD patients with a higher baseline mMRC dyspnea scale and CAT score experience greater symptom reduction by pharmacotherapy.