Outcome of 248 patients with obstructive sleep apnea syndrome treated by nasal continuous positive airway pressure. Study of compliance and time-course of Apnea-Hypopnea index

Between 1990 and 1995, 369 patients were investigated Sor obstructive sleep apnea syndome (OSAS) by polysomnography. Among them, 248 patients with a m ean Apnea-Hyponea index (AHI) of 37.7 per hour were treated by nasal contin uous positive airway pressure (n-CPAP). Mean follow Lip was 39.5 +/- 20.4 m onths. In this group, 23 patients (9.2%) refused nCPAP immediately or after the first night and 39 (15.7%) gave Itp later 15 patients (6%) died during the period of the study. The cumulative compliance reached 70% at 72 month s, Non compliant patients usually gave up n-CPAP before the end of the firs t year We compared the group of 150 patients always treated at the date of 31/12/95 with the group of 62 patients who refused nCPAP initially or gave up later There was no difference in clinical parameters or polysomnographic data between the two groups. In 94 patients treated by nCPAP for more than a year we evaluated the outco me of AHI by a polysomnography performed after 72 hours of nCPAP cessation. Mean AHI of the group at this rime was 38.2 +/- 20.3/h and was well correl ated with the initial index (r = 0.41, p < 0.0001). However for 28 patients (29.7%) we observed, at the time of this second AHI determination a variat ion (plus or minus) of at least 50% of the index. 6 patients, without any s ignificative weigth loss, had an AHI below 5/h at this second determination . In this small group nCPAP was interrupted for 6 to 12 months, then anothe r polysomnography was performed At this time mean AHI was 42.4/h and clinic al symptoms had reappeared in all patients. This study demonstrated that compliance to nCPAP in OSAS patients is good. No clinical or polysomnographic factors allow to predict non compliance. AH I is not modified by long term treatment with nCPAP.