Measuring respiratory symptoms of COPD: performance of the EXACT- Respiratory Symptoms Tool (E-RS) in three clinical trials

• Published in: Respiratory research Vol. 15; no. 1; p. 124
• Main Authors: Leidy, Nancy K, Murray, Lindsey T, Monz, Brigitta U, Nelsen, Linda, Goldman, Mitchell, Jones, Paul W, Dansie, Elizabeth J, Sethi, Sanjay
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 07-10-2014; BioMed Central
• Subjects: Aged; Analysis; Chronic obstructive pulmonary disease; Clinical trials; Cough - diagnosis; Cough - etiology; Cough - physiopathology; Diaries; Disease Progression; Double-Blind Method; Drug dosages; Dyspnea - diagnosis; Dyspnea - etiology; Dyspnea - physiopathology; Exercise Test; Exercise Tolerance; Female; Health Status; Humans; Lung - drug effects; Lung - physiopathology; Male; Measurement; Medical research; Medicine, Experimental; Middle Aged; Patient outcomes; Patients; Pharmaceutical industry; Predictive Value of Tests; Pulmonary Disease, Chronic Obstructive - complications; Pulmonary Disease, Chronic Obstructive - diagnosis; Pulmonary Disease, Chronic Obstructive - drug therapy; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary manifestations of general diseases; Qualitative research; Questionnaires; Reproducibility of Results; Severity of Illness Index; Sputum; Studies; Surveys and Questionnaires; Time Factors; Treatment Outcome; United Kingdom; United States > US
• DOI: 10.1186/s12931-014-0124-z
• EISSN: 1465-993X; 1465-9921

Symptomatic relief is an important treatment goal for patients with COPD. To date, no diary for evaluating respiratory symptoms in clinical trials has been developed and scientifically-validated according to FDA and EMA guidelines. The EXACT - Respiratory Symptoms (E-RS) scale is a patient-reported outcome (PRO) measure designed to address this need. The E-RS utilizes 11 respiratory symptom items from the existing and validated 14-item EXACT, which measures symptoms of exacerbation. The E-RS total score quantifies respiratory symptom severity, and 3 domains assess breathlessness, cough and sputum, and chest symptoms.
This study examined the performance of the E-RS in each of 3 controlled trials with common and unique validation variables: one 6-month (N = 235, US) and two 3-month (N = 749; N = 597; international). Subjects completed the E-RS as part of a daily eDiary. Tests of reliability, validity, and responsiveness were conducted in each dataset.
In each study, RS-Total score was internally consistent (Cronbach α) (0.88, 0.92, 0.92) and reproducible (intra-class correlation) in stable patients (2 days apart: 0.91; 7 days apart: 0.71, 0.74). RS-Total scores correlated significantly with the following criterion variables (Spearman's rho; p < 0.01, all comparisons listed here): FEV1% predicted (-0.19, -0.14, -0.15); St. George's Respiratory Questionnaire (SGRQ) (0.65, 0.52, 0.51); Breathlessness, Cough, and Sputum Scale (BCSS) (0.89, 0.89); modified Medical Research Council dyspnoea scale (mMRC) (0.40); rescue medication use (0.43, 0.42); Functional Performance Inventory Short-Form (FPI-SF) (0.43); 6-minute walk distance (6-MWT) (-0.30, -0.14) and incremental shuttle walk (ISWT) (-0.18) tests. Correlations between these variables and RS-Breathlessness, RS-Cough and Sputum, RS-Chest Symptoms scores supported subscale validity. RS-Total, RS-Breathlessness, and RS-Chest Symptoms differentiated mMRC levels of breathlessness severity (p < 0.0001). RS-Total and domain scores differentiated subjects with no rescue medication use and 3 or more puffs (p < 0.0001). Sensitivity to changes in health status (SGRQ), symptoms (BCSS), and exercise capacity (6MWT, ISWT) were also shown and responder definitions using criterion- and distribution-based methods are proposed.
Results suggest the E-RS is a reliable, valid, and responsive measure of respiratory symptoms of COPD suitable for use in natural history studies and clinical trials.
MPEX: NCT00739648 ; AZ1: NCT00949975 ; AZ 2: NCT01023516.