Agreement between 95th percentile pressure based on a 7-night auto-adjusting positive airway pressure trial vs. equation-based predictions in sleep apnea.

Study Objectives: to analyze the agreement between effective CPAP-determined on the basis of a 7-night auto-adjusting positive airway pressure (APAP) trial at home with that obtained through 5 different predictive equations.

Methods: Data were collected from consecutive CPAP-naive patients with OSA who underwent a 7-night non-attended home-setting APAP trial. The 95th percentile APAP pressure was considered as the effective CPAP and also as the reference variable against which the equation-based predictions were compared. All patients fulfilled the following criteria: residual respiratory disturbances index (RDI) < 10 events/h, average air leak < 0.4 L/sec and > 4 h of use per night during the APAP trial.

Results: A total of 100 consecutive patients (70 men) with the following characteristics were included: mean age 49 +/- 11 years, body mass index 34 +/- 4 kg/m2, diagnostic Epworth Sleepiness Scale score 14 +/- 7, diagnostic RDI 56 +/- 28 events/h, 95th percentile APAP 11 +/- 2 cm H2O, hours of use per night 6.2 +/- 1.3, and residual RDI 5 +/- 2 events/h. A poor level of agreement between the 95th percentile pressure and the pressures obtained through 5 predictive equations was observed (the intra-class correlation coefficient ranged from 0.17 to 0.32).

Conclusions: The disagreement observed between the effective CPAP determined through a 7-night APAP trial and the pressures obtained by the predictive equations suggest that long-term CPAP prescriptions based on predictive equations may be improper.