Mortality in middle-aged men with obstructive sleep apnea in Finland.

INTRODUCTION: Obstructive sleep apnea (OSA) has been associated with an elevated rate of cardiovascular mortality. However, this issue has not been investigated in patients with elevated proneness to cardiovascular diseases. Our hypothesis was that OSA would have an especially adverse effect on the risk of cardiovascular mortality in Finnish individuals exhibiting elevated proneness for coronary heart diseases. METHODS: Ambulatory polygraphic recordings from 405 men having suspected OSA were retrospectively analyzed. The patients were categorized regarding sleep disordered breathing into a normal group (apnea hypopnea index (AHI) < 5, n = 104), mild OSA group (5 ≤ AHI < 15, n = 100), and moderate to severe OSA group (AHI ≥ 15, n = 201). In addition, basic anthropometric and health data were collected. In patients who died during the follow-up period (at least 12 years and 10 months), the primary and secondary causes of death were recorded. RESULTS: After adjustment for age, BMI, and smoking, the patients with moderate to severe OSA suffered significantly (p < 0.05) higher mortality (hazard ratio 3.13) than their counterparts with normal recordings. The overall mortality in the moderate to severe OSA group was 26.4 %, while in the normal group it was 9.7 %. Hazard ratio for cardiovascular mortality was 4.04 in the moderate to severe OSA and 1.87 in the mild OSA group. CONCLUSIONS: OSA seems to have an especially adverse effect on the cardiovascular mortality of patients with an elevated genetic susceptibility to coronary heart diseases. When considering that all our patients had possibility of continuous positive airway pressure treatment and our reference group consisted of patients suffering from daytime somnolence, the hazard ratio of 4.04 for cardiovascular mortality in patients with moderate to severe disease is disturbingly high.

Design, construction and evaluation of an ambulatory device for screening of sleep apnea.

Obstructive sleep apnea syndrome (OSAS) is a major public health problem. The golden reference for diagnosing OSAS is the sleep-laboratory based polysomnography (PSG). However, screening of population for OSAS may be practical and cost efficient only through ambulatory home recordings. In this work we aimed to design, construct and evaluate a novel ambulatory device for these recordings. The device was designed to record breathing movements, nasal and oral flow, position, snore, blood oxygen saturation and heart rate. The first part of clinical evaluation was done by recording 19 patients simultaneously with the novel device and with clinical reference instrumentation at a sleep laboratory. In the simultaneous recordings, no statistically significant difference was detected in the apnea-hypopnea index. All patients were correctly diagnosed, as compared to the reference instrumentation, with the novel ambulatory device. The second part of clinical evaluation was conducted through 323 ambulatory home recordings of which 275 (193 males and 82 females) were of diagnostically acceptable quality. A total of 106 and 169 recordings were successfully conducted with the novel device and a commercial ambulatory device, respectively. Both devices showed similar diagnostic capability in detecting sleep apnea. The novel device was found clinically applicable, technically reliable and sensitive for the diagnostics of OSAS.