SAN FRANCISCO -- Poor sleep quality was strongly associated with an increased risk for COPD exacerbations over 18 months of follow up in an analysis of data from a Canadian prospective cohort study reported here.
Every two point increase in self-reported Pittsburgh Sleep Quality Index () score was associated with about a 10% increased relative risk of having a COPD exacerbation over the study follow-up, adjusted for exacerbation risk factors, said lead researcher , who is a pulmonary medicine fellow at McGill University, Montreal, Canada.
Shorofsky presented the analysis of data from the Canadian Cohort of Obstructive Lung Disease () in poster presentation at the .
"Our finding suggest that poor sleep and COPD are strongly related, but it is a chicken-egg issue," Shorofsky told ѻý Today. "We can't really say if exacerbations caused poor sleep or if poor sleep contributed to exacerbations. We need additional studies to figure this out."
Shorofsky said the relationship of insomnia and other sleep disturbances to COPD exacerbations has not been widely studied.
"We know that sleep disorders are very common in the general population of older people and so is COPD," he said. "We know there is overlap between the two, but we haven't really looked at how sleep disorders affect COPD-related outcomes."
The researchers hypothesized that COPD patients with poor sleep quality, assessed using the PSQI, would be more likely to have exacerbations during 18-months of follow up and they tested the theory in the CanCOLD dataset, which is an ongoing longitudinal study with more than 1,500 COPD patients from nine urban and suburban areas in Canada.
Exacerbations were self-reported by each study participant and confirmed by telephone by a study coordinator every 3 months, and they were classified by severity based on symptoms, need for medication, and need for hospitalization or other healthcare services.
Sleep quality was measured at baseline, with poor sleepers defined as having PSQI scores of >5 and good sleepers having a PSQI score of ≤5. PSQI was also subdivided into three component scores assessing sleep efficiency, sleep quality, and daily disturbance.
The association between poor sleep quality and exacerbations was adjusted for baseline age, sex, body mass index, FEV1% predicted, and current smoking.
The researchers found that for every two-point increase in baseline PSQI score there was a 10% increase in risk of symptom-based exacerbations over 18 months in models adjusted for confounders.
And for every one-point increase in baseline daily sleep disturbance score there was a 50% increase in risk of both symptom- and event-based exacerbations over the same period.
Strengths of the study included the longitudinally-followed population sample of patients with mild to moderate COPD, the researchers indicated. Limitations included the self-reported measure of sleep and the potential for recall bias when assessing exacerbations.
Despite the limitations, Shorofsky and colleagues concluded that their findings suggest that optimization of sleep quality has the potential to reduce COPD exacerbations or that an increase in COPD symptoms may be related to poor sleep.
"Further research will be required to better characterize the interaction between objective sleep disturbances and COPD control and identify the pathophysiologic mechanisms involved," the researchers noted in their poster.
Primary Source
American Thoracic Society
Shorofsky M, et al "A population-based study of sleep disorders in chronic obstructive pulmonary disease: sleep quality and acute exacerbations of COPD" ATS 2016; Abstract 1570.