title: Utility of formulas predicting the optimal nasal continuous positive airway pressure in a Greek population.
abstract: BACKGROUND
  There have been reports that optimal CPAP pressure can be predicted from a previously derived formula, with the Hoffstein formula being the most accurate and accepted in the literature so far. However, the validation of this predictive model has not been applied in different clinical settings. Our aim was to compare both the Hoffstein prediction formula and a newly derived formula to the CPAP pressure setting assessed during a formal CPAP titration study.
  
  
  METHODS
  We prospectively studied 1,111 patients (871 males/240 females) with obstructive sleep apnea hypopnea syndrome (OSAHS) undergoing a CPAP titration procedure. In this large population sample, we tested the Hoffstein formula, utilizing body mass index (BMI), neck circumference and apnea/hypopnea index (AHI), and we compared it with our new formula that included not only AHI and BMI but also smoking history and gender adjustment.
  
  
  RESULTS
  We found that using the Hoffstein prediction formula, successful prediction (predicted CPAP pressure within ±2 cm H(2)O compared to the finally assessed optimum CPAP pressure during titration) was accomplished in 873 patients (79%), with significant correlation between CPAP predicted pressure (CPAPpred(1)) and the optimum CPAP pressure (CPAPopt) [r = 0.364, p < 0.001]. With the new formula, including smoking history and gender adjustment, successful prediction was accomplished in 1,057 patients (95%), with significant correlation between CPAP predicted pressure (CPAPpred(2)) and the CPAPopt (r = 0.392, p < 0.001). However, there was a highly significant correlation between the two formulas (r = 0.918, p < 0.001).
  
  
  CONCLUSIONS
  We conclude that the level of CPAP necessary to abolish sleep apnea can be successfully predicted from both equations, using common clinical measurements and prediction formulas that may be useful in calculating the starting pressure for initiating CPAP titration. It may also be possible to shorten CPAP titration and perhaps in selected cases to combine it with the initial diagnostic study.
authors.affiliation: Department of Thoracic Medicine, University of Crete, Heraklion, Greece.
authors.forename: Sophia E
authors.initials: SE
authors.lastname: Schiza
authors.forename: Izolde
authors.initials: I
authors.lastname: Bouloukaki
authors.forename: Charalampos
authors.initials: C
authors.lastname: Mermigkis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Panagou
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Tzanakis
authors.forename: Violeta
authors.initials: V
authors.lastname: Moniaki
authors.forename: Eleni
authors.initials: E
authors.lastname: Tzortzaki
authors.forename: Nikolaos M
authors.initials: NM
authors.lastname: Siafakas
mesh_terms: D000328:Adult; D000368:Aged; D000399:Air Pressure; D000465:Algorithms; D045422:Continuous Positive Airway Pressure / Q000592:standards*; D003431:Cross-Cultural Comparison; D005260:Female; D006115:Greece; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000628:therapy*; D013223:Statistics as Topic