[Risk assessment for sleep apnea syndrome and excessive daytime sleepiness in patients with chronic obstructive pulmonary disease].

AIM: The objective of this study was to examine the risk of sleep apnea syndrome in patients with chronic obstructive pulmonary disease (COPD) and to determine correlation with the associated cardiovascular comorbidity in these patients. Chronic and occasional sleep disturbances represent a problem for millions of people worldwide. COPD is a multisystem disease and the leading cause of mortality and morbidity in the world. It is estimated that it will be the third cause of death in the world by 2020. Poor quality of sleep in patients with COPD occurs as a result of reduced oxygen saturation, hypercapnia, and the use of auxiliary respiratory muscles.

METHODS: The study included 47 patients with COPD, examined at the Department of Pulmonology, Clinical Department of Internal Medicine, Osijek University Hospital Center in 2011. The respondents answered questions from the Croatian version of the Snoring, Tired, Observed, Pressure (STOP) questionnaire, which examines the risk of sleep apnea syndrome, and the Epworth Sleepiness Scale, which examines excessive daytime sleepiness. The respondents also provided data related to the current smoking status, bronchodilation therapy they apply at home, the associated cardiovascular comorbidity related to coronary heart disease (previous myocardial infarction, angina pectoris), cerebrovascular incident, diabetes, asthma, gastroesophageal reflux disease (GERD) and anxiety-depressive disorder.

RESULTS: According to the STOP questionnaire, the risk of sleep apnea syndrome was recorded in 35 (74.5%) respondents. Patients at risk had a higher frequency of comorbidities such as hypertension, diabetes mellitus type 2 and GERD. Excessive daytime sleepiness was recorded in 14.9% of patients with COPD and the mean daytime sleepiness scored 4.76 points. In patients at a high risk according to the STOP questionnaire, the mean daytime sleepiness was 6.24 points versus 3.72 points in the group at a low risk. Snoring was present in 23 (49%), excessive tiredness in 27 (57%), and cessation of breathing during sleep in every other person in 4 cases (8.5% of patients). The t-test showed no significant differences in oxygen saturation, partial O2 and CO2 pressures between the groups of non-risk and high-risk patients according to the STOP questionnaire.

CONCLUSION: For assessing the risk of sleep apnea syndrome in patients with COPD, the STOP questionnaire as a screening method has a significant role. Because of the high risk of sleep apnea syndrome in patients with COPD and considering the high level of associated cardiovascular comorbidity, it is necessary to perform polysomnography in patients at risk for timely detection and treatment of the syndrome, thus preventing its harmful consequences, with special reference to reduction of mortality in this population.