Effectiveness of unattended ambulatory sleep studies for the diagnosis and treatment of OSAS.

Background: Unattended home sleep studies have been implemented to minimize the cost and delay in establishing obstructive sleep apnoea syndrome (OSAS) diagnosis and therapy. However, their accuracy and validity remain disputed. The purpose of our study is to assess their effectiveness (i.e. their technical reliability in real life conditions).

Setting: Private sleep unit attending to private and social security patients.

Population: Consecutively admitted patients, aged over 18 years, referred to our clinic for confirmation or treatment of OSAS without co-morbidities.

Methods: A clinical history was obtained for each patient with special attention to sleep, smoking habit, educational level and type of insurance. Chest X-ray and forced spirometry were performed. For the portable respiratory recording device an eight-channel polygraph was used and for continuous positive airway pressure (CPAP) titration an automatic positive airway pressure device was applied; both instruments were previously validated. Patients were instructed how to use the devices at the clinic and then applied them at home by themselves.

Results: For diagnostic sleep studies, 145 out of 150 (96.7%: CI: 92.4-98.9) and for CPAP titration 42 out of the 61 patients (69%: CI: 56.4-81.3) performed the sleep study correctly according to the pre-established criteria. No statistically significant differences were found between correct performance and educational level, sex, smoking habit or type of health insurance.

Conclusions: (1) Unattended home sleep studies appear as effective as in-hospital studies for diagnosis of OSAS without co-morbidities; (2) for CPAP titration, the effectiveness was slightly lower; and (3) factors such as patients' educational level or type of health insurance do not appear to influence outcome.