Prediction of optimal CPAP pressure and validation of an equation for Asian patients with obstructive sleep apnea.
BACKGROUND
The Hoffstein formula is the most widely used equation to predict optimal CPAP pressure in patients with obstructive sleep apnea, but it is based on data from white patients. The purpose of this study was to develop an equation for optimal CPAP based on data from Asian patients, and to compare this new formula with the Hoffstein formula.


METHODS
We retrospectively reviewed the records of 356 Korean subjects with obstructive sleep apnea who had undergone successful CPAP titration, and randomly divided them into 2 groups, with 178 subjects per group. In group 1 we used stepwise multiple linear regression analysis to develop a predictive equation for optimal CPAP. Then we compared our equation with the Hoffstein equation in group 2.


RESULTS
A predictive equation was: predicted pressure (cm H2O) = 6.656 + 0.156 × (body mass index [kg/m(2)]) - 0.071 × (minimal SpO2 [%]) + 0.041 × (respiratory disturbance index) + 0.094 × (score of Epworth Sleepiness Scale). This equation accounted for 38.9% of the total variance (P < .001). Proportions of optimal estimation of CPAP pressure were 38.8% and 36.5% in this equation and the Hoffstein equation, respectively. The Hoffstein formula significantly underestimated CPAP, compared with our formula.


CONCLUSIONS
Although our equation was somewhat better to predict optimal CPAP level in Asian subjects than the Hoffstein equation, the CPAP prediction equation did not accurately predict the prescribed CPAP level. Therefore, the usefulness of the CPAP prediction formula is limited in some clinical settings.
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Gha-Hyun
GH
Lee
Min Ju
MJ
Kim
Eun Mi
EM
Lee
Cheon Sik
CS
Kim
Sang-Ahm
SA
Lee
D000328:Adult; D044466:Asian People; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D011237:Predictive Value of Tests; D011312:Pressure; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D044465:White People
D010100:Oxygen