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CanCOLD: Poor sleep quality linked to COPD exacerbations

Patients with poor sleep quality scores were at increased risk for exacerbations of COPD, according to 18-month follow-up results of the CanCOLD study.

Researchers in Canada evaluated the association between subjective sleep disturbances and the risk for exacerbation in COPD among 1,040 patients included in the prospective, multicenter, population-based cohort CanCOLD study.

Overall, 480 patients had diagnosed COPD.

All patients had baseline Pittsburgh Sleep Quality Index (PSQI) data available and completed 18-month follow-up. The researchers additionally used a three-factor analysis that assessed sleep efficiency, quality and disturbances:

• Factor 1, sleep efficiency, included sleep duration and efficiency components (score 0-6);
• Factor 2, sleep quality, included perceived sleep quality, sleep latency and sleep medication use components (score 0-9); and
• Factor 3, daily disturbances, included sleep disturbances — bathroom use, breathing issues and pain — and sleep-related daytime dysfunction — sleepiness and enthusiasm components (score 0-6).

Investigators found that those with one or more symptom-based exacerbations of COPD during the 18-month follow-up period had higher median baseline PSQI scores (6 vs. 5; P = .01), and higher scores in Factors 2 and 3, compared with those without exacerbations of COPD. Those with one or more symptom-based exacerbations of COPD were also more likely to have poor sleep quality with a baseline global PSQI score greater than 5 (50.3% vs. 37.3%; P = .01).

In univariable and multivariable analyses that adjusted for age, sex, BMI, smoking status, depression, angina and baseline inhaled respiratory medications, researchers found that all patients with diagnosed COPD and had higher baseline PSQI scores, Factor 1 and Factor 3 scores, and were at increased risk for symptom-based exacerbations of COPD.

In repeat analyses that excluded for self-reported asthma (n = 320), results showed a significant effect of sleep disturbances and daytime dysfunction on exacerbations of COPD. Higher PSQI scores were associated with increased symptom-based exacerbations (adjusted RR = 1.09; 95% CI, 1.01-1.18) and event-based exacerbations (aRR = 1.1; 95% CI, 1-1.21).

“Further studies will be required to explore the mechanisms of interaction between sleep disturbances and COPD exacerbations, and to determine whether interventions to improve sleep quality can modify COPD-related outcomes,” Matthew Shorofsky, MD, researcher in the respiratory epidemiology and clinical research unit at the Research Institute of the McGill University Health Centre at McGill University in Montreal, and colleagues wrote. “Routine assessment of sleep quality may be a useful clinical predictor for exacerbation risk, and a tool to identify those who might benefit from closer follow-up and intervention.” – by Jennifer Southall

Disclosures: Shorofsky reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. The study was funded by the Canadian Respiratory Research Network.