['Continuous positive airway pressure (CPAP) is the therapy of choice for the treatment of obstructive sleep apnea (OSA). Not all patients can use CPAP therapy with adequate compliance. There is a need to develop more comfortable modes. Auto bi-level Pressure Relief-Positive Airway Pressure (ABPR-PAP) can be an alternative. We conducted a prospective double-blind, randomised trial to evaluate the efficacy and compliance of ABPR-PAP compared with CPAP in OSA patients.', 'We included 35 CPAP naive patients (age 53.3 ± 10.3 years, BMI 31.0 ± 5.0 kg/m(2), ESS 10.0 ± 4.2) diagnosed with moderate to severe OSA who underwent a successful CPAP titration. Patients were randomised into the CPAP or the ABPR-PAP treatment group. We used the same device (BIPAP® Auto, Philips Respironics) for CPAP or ABPR-PAP. Apnea-hypopnea index (AHI) was determined using polysomnography before (AHI 40.6 ± 18.3 per hour) and after treatment.', 'Eighteen patients received CPAP and the remaining 17 received APBR-PAP. Groups were similar in terms of demographics and OSA severity. There were no serious adverse events during the trial. CPAP was fixed by a sleep expert and ABPR-PAP varied (range 5-15 cmH(2)O). AHI decreased in the CPAP group to 6.4 ± 5.7 per hour and in the ABPR-PAP group to 4.8 ± 3.6 per hour in the first night (N = 35). After 3 months, the AHI decreased in the CPAP group to 4.4 ± 5.3 per hour and in the ABPR-PAP group to 2.6 ± 3.8 per hour (N = 32). Differences between the groups were not statistically significant. There were no differences in compliance.'] Is auto bi-level pressure relief-PAP as effective as CPAP in OSA patients -- a pilot study?