Study objective: To develop and validate a brief, computer-scannable, self-administered questionnaire to monitor health-related quality of life in patients with COPD. The Seattle Obstructive Lung Disease Questionnaire (SOLQ) consists of 29 items measuring four health dimensions: physical function, emotional function, coping skills, and treatment satisfaction.
Methods: A series of studies was performed to assess reliability, validity, and responsiveness. Internal consistency was measured using a cross-sectional survey of 203 COPD patients. Reproducibility was tested over a 4-month interval among 97 patients with self-reported stable conditions. To assess construct validity, SOLQ scales were correlated with corresponding Chronic Respiratory Disease Questionnaire (CRDQ) scales, the COPD Self-Efficacy Scale (CSES), percent predicted FEV1, and 6-min walk test. Treatment satisfaction scores of 920 subjects were correlated with a general measure of patient satisfaction. Baseline and follow-up scores of subjects were compared to assess treatment responsiveness.
Results: SOLQ scales were reliable (Cronbach's alpha 0.79 to 0.93, and intraclass correlation coefficients 0.64 to 0.87). Change in SOLQ scores correlated with corresponding CRDQ scales: dyspnea, r=0.42; emotional burden, r=0.49; mastery, r=0.36. Coping skills correlated highly with CSES, r=0.93. Treatment satisfaction correlation was r=0.54. Significant changes occurred in all three scales postintervention.
Conclusion: The SOLQ is a reliable, valid, and responsive measure of physical and emotional function, coping skills, and treatment satisfaction. Brief, self-administered, and computer scannable, it is useful in monitoring long-term outcomes among large groups of COPD patients.