Continuous positive airway pressure (CPAP) is widely used to treat obstructive sleep apnea; however, there is little evidence to support the idea that it improves outcomes. CPAP does not cure the underlying illness; rather, it prevents the periodic collapse of the upper airway during sleep. Maintaining the airway with CPAP decreases the intermittent hypoxia resulting from airway obstruction that disrupts normal sleep patterns. Because CPAP is expensive and uncomfortable, better evidence is needed to demonstrate that it improves quality of life to justify its use. Ballester and colleagues compared the effectiveness of conservative management alone and in combination with CPAP in improving symptoms, daytime function, and self-perceived health status.
Patients with an established diagnosis of sleep apnea/hypopnea syndrome were eligible for the study. Inclusion criteria consisted of severe clinical symptoms and an apnea/hypopnea index score of greater than 15 without symptoms or greater than 30 with symptoms. Patients were randomized into two groups in a ratio of two patients in the treatment group for every one patient in the control group. Patients with unstable cardiovascular disease or hazardous jobs were excluded from the study. Patients in the control group followed conservative measures alone, including completing enough hours of sleep every night, sleeping on their side, avoiding sedatives and alcohol, and losing weight by following a home diet. Those in the treatment group followed the same conservative measures and were fitted for CPAP. Patients in the latter group attended a full-day training program, were fitted with the mask and took a short test nap in the sleep unit so they could be monitored by staff. Titration was performed with the automatic Rescare AutoSet system under staff supervision.
Patients completed questionnaires before treatment was initiated and then three months later. Questions about sleepiness, apnea symptoms, and daytime function were included in the assessment. Perceived health status was assessed using the Nottingham Health Profile questionnaire.
Although both groups showed improvement with treatment on all scales, the CPAP group showed significantly more improvement on key items. The Nottingham Health Profile is a generic instrument with six domains. In the more relevant domains, such as energy, the CPAP group showed significant improvement. In fact, the analysis using the most relevant questionnaires showed that only 35 percent of patients showed improvement in the conservative group, while 78 percent of patients showed improvement in the CPAP group. The odds of group 2 showing improvement over group 1 were 6.52 (CI: 95 percent).
The authors conclude that treating patients with CPAP plus conservative measures improves outcomes compared with use of conservative measures alone in patients with moderate to severe obstructive sleep apnea.