Original ArticleSleep profile and symptoms of sleep disorders in patients with stable mild to moderate chronic obstructive pulmonary disease
Introduction
Chronic obstructive pulmonary disease (COPD) is one of the world’s most leading causes of morbidity and mortality [1]. In addition to the typical respiratory symptom profile including shortness of breath, chronic cough, and sputum production, patients with COPD may also experience symptoms such as snoring, witnessed apneas, and/or excessive daytime sleepiness, thus being predisposed to the development of obstructive sleep apnea (OSA) [2], [3], [4]. The overall likelihood for these symptoms to be associated with an actual diagnosis of OSA, however, remains as low as 5% [5]. Similarly, more recent results from the Sleep Heart Health Study suggested no evidence of a higher prevalence of sleep apnea in patients with mild COPD [6].
Irrespective of the above mentioned sleep apnea symptoms, patients with COPD frequently report impaired quantity and quality of sleep [7], [8], [9], [10]. Kinsman et al. [9] reported that sleep disturbances ranked third after dyspnea and fatigue and nearly one-half of the patients had sleep difficulties “always” or “almost always.” Cormick et al. [10] similarly reported fragmented sleep and difficulty falling asleep in patients with severe COPD compared to respective controls. The presence of sleep problems in COPD is of particular importance, as sleep quality is a major determinant of overall health status and quality of life in these patients [11], [12], [13]. Most prior studies of sleep quality in patients with COPD, however, have focused on patients with moderate to severe COPD [10], [14] or have failed to exclude underlying sleep apnea using overnight sleep testing [3], [4], [7], [8].
The aim of the present report was to systematically investigate sleep profile and symptoms associated with sleep disorders in patients with stable mild to moderate COPD in comparison with matched controls.
Section snippets
Methods
Between July 2004 and March 2006 232 consecutive patients with COPD recruited from the hospital outpatient clinic were screened for eligibility in this study. Inclusion criteria were (1) diagnosis of COPD stage II and III for more than 12 months based on the definition of the European Respiratory Society (Ratio of Forced Expiratory Volume to Forced Vital Capacity <70% plus Forced Expiratory Volume between 30% and 80% predicted) [15]; (2) age > 40 years; (3) stable condition, defined as a stable
Clinical data and polysomnographic variables
The mean values for age, BMI, and the gender ratio were non-significant between groups, indicating a good population match (Table 1). Patients with COPD had an overall lower arterial paO2 and higher pack-years of smoking compared to controls without COPD.
There were no significant differences in AHI, arousal index, % sleep time spent in slow wave sleep, or sleepiness score between the groups. Patients with COPD, however, had overall lower sleep efficiency, a lower total sleep time, lower% sleep
Discussion
The present study investigated polysomnographic variables and symptoms associated with sleep disorders in patients with mild to moderate COPD and matched controls without airflow obstruction. We observed significant differences in overnight sleep parameters, calculated symptom scale scores and individual symptom frequencies between the two groups.
Conflict of Interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: doi:10.1016/j.sleep.2010.08.017.
Acknowledgment
AV collected the data and prepared the manuscript. PL assisted in interpretation of study findings and review of the manuscript. HL was responsible for statistical analysis. IM was responsible for performing and analysis of polysomnographic recordings. OCB was the principal investigator. He reviewed the dataset and provided funding through the Ludwig-Boltzmann-Institute for COPD. We are grateful to Helmuth Rauscher, MD for his support in data collection.
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