Longitudinal associations between sleep disturbance and disease severity in patients with COPD

Sleep disturbance is a common complaint among patients with chronic obstructive pulmonary disease (COPD). Studies examining the associations between sleep disturbance and COPD severity have primarily been cross-sectional and produced conflicting results. We extended previous research by investigating the bidirectional longitudinal associations between sleep disturbance and indicators of COPD severity including airway obstruction, dyspnea, health status, exercise capacity, hyperinflation, and diffusing capacity of the lung (DLCO). We used longitudinal data from the COPD Specialized Center for Clinically Oriented Research (SCCOR) prospective cohort. One hundred fifty-seven patients with COPD (54.1% male, 66.3 ± 6.4 years) completed assessments at baseline and 2-year follow-up. Primary outcomes of interest were: sleep disturbance based on a single item from the Beck Depression Inventory; airflow obstruction, defined by FEV1% predicted from spirometry; health status, as measured by the St. George’s Respiratory Questionnaire; exercise capacity, as determined by walking distance (meters) during an incremental shuttle walk test; dyspnea, as measured by the modified Medical Research Council scale; DLCO, determined by single breath carbon monoxide diffusion; and hyperinflation, defined by residual volume from body plethysmography. Linear and logistic regression analyses were conducted, correcting for baseline outcome severity. After controlling for covariates of age, sex, race, body mass index, and smoking status, sleep disturbance was associated with worse health status at baseline. Using longitudinal follow-up data, greater disease severity including airflow obstruction, dyspnea, health status, exercise capacity, and DLCO independently predicted sleep disturbance at 2-year follow-up. Baseline sleep disturbance was not associated with subsequent disease severity. Disease severity predicts future sleep disturbance in COPD patients. This suggests that COPD severity may be a risk factor for the development of sleep problems, and therefore better COPD control may be a preventative strategy for sleep disturbance.