Background: A patient report of respiratory symptoms in COPD is essential to successfully monitoring disease, adjusting treatment, and evaluating outcomes.
Objective: To develop empirically based guidelines for interpreting mean changes in symptom scores using the Breathlessness, Cough, and Sputum Scale (BCSS).
Methods: Analyses were performed on data from three multinational trials (n = 2,971). Mean changes in BCSS score with treatment were examined by physician and patient ratings of treatment efficacy, juxtaposed with percentage change in symptoms, statistical effect size (ES), DeltaFEV(1), and change in St. George Respiratory Questionnaire (SGRQ) score. BCSS scores during an exacerbation were examined relative to changes in peak expiratory flow and rescue medication use.
Results: Mean baseline BCSS total score was 5.2 +/- 2 (+/- SD); 90% of scores were between 2 and 9. Highly efficacious treatment (n = 257; physician rating) was associated with a DeltaBCSS total score of - 1.3 +/- 1.8, representing a 24% improvement (ES = 0.7), and corresponding to a 10% improvement in FEV(1) and DeltaSGRQ score total of - 10.3 +/- 13.8. Similar changes in BCSS score were observed during recovery from an exacerbation (n = 713; - 1.3 +/- 1.8). Mean change with moderately efficacious treatment (n = 965) was - 0.7 +/- 1.8, a 13% improvement (ES = 0.3) corresponding to DeltaSGRQ total score of - 6.8 +/- 12.6. Mildly efficacious treatment (n = 891) was associated with a change of - 0.35, a 7% improvement (ES = 0.18), with a DeltaFEV(1) <1% and DeltaSGRQ total score of - 2.6 +/- 11.7.
Conclusions: Patient-reported daily symptom data are sensitive to change and useful for both observational studies and controlled clinical trials of patients with COPD. A mean DeltaBCSS total score > 1.0 represents substantial symptomatic improvement, changes of approximately 0.6 can be interpreted as moderate, and changes of 0.3 can be considered small.