Development of a quantifiable symptom assessment tool for patients with chronic bronchitis: the Chronic Bronchitis Symptoms Assessment Scale. 
Clinical trials that rely solely on physiologic outcomes may underestimate effects of interventions on patients' symptoms and well-being.  We sought to develop and validate an instrument to reliably assess symptom severity and frequency in therapeutic trials for patients with chronic bronchitis.  We performed a series of psychometric studies that determined instrument content and assessed validity and reliability.  The final version of the Chronic Bronchitis Symptoms Assessment Scale (CBSAS) comprised 15 scored items (16 items total).  The instrument demonstrated strong reliability with moderate to high item correlations with total scores (0.41-0.80) and an overall Cronbach's alpha of 0.91.  As expected, scores were at the bottom of the range for patients without a history of previous lung disease, and no ceiling effect was seen in the most severely obstructed patients.  The CBSAS demonstrated statistically significant and moderate to strong association with spirometry, (post bronchodilator, % pred FEV1, r = -0.42, % pred FVC, r = -0.50), SGRQ (total, r = 0.67) and SOBQ (r = 0.50).  The Chronic Bronchitis Symptoms Assessment Scale is an easy to administer, once daily or once weekly, valid and reliable outcome measure for assessing symptom severity among patients with chronic bronchitis.