[Results of 248 patients with sleep apnea syndrome treated by continuous positive pressure ventilation between 1990 and 1995. A study of compliance and outcome of the apnea-hypopnea index]

Abstract

Between 1990 and 1995, 369 patients were investigated for obstructive sleep apnea syndrome (OSAS) by polysomnography. Among them, 248 patients with a mean Apnea-Hyponea index (AHI) of 37.7 per hour were treated by nasal continuous positive airway pressure (n-CPAP). Mean follow up was 39.5 +/- 20.4 months. In this group, 23 patients (9.2%) refused nCPAP immediately or after the first night and 39 (15.7%) gave up later. 15 patients (6%) died during the period of the study. The cumulative compliance reached 70% at 72 months. Non compliant patients usually gave up n-CPAP before the end of the first 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 outcome of AHI by a polysomnography performed after 72 hours of nCPAP cessation. Mean AHI of the group at this time was 38.2 +/- 20.3/h and was well correlated 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 variation (plus or minus) of at least 50% of the index. 6 patients, without any significative 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 another polysomnography was performed. At this time mean AHI was 42.4/h and clinical 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. AHI is not modified by long term treatment with nCPAP.