Accuracy of the clinical parameters and oximetry to initiate CPAP in patients with suspected obstructive sleep apnea.

OBJECTIVE

The aim of this study was to assess the accuracy of oximetry and the clinical parameters for the prescription of continuous positive airway pressure (CPAP) in patients with suspected obstructive sleep apnea syndrome (OSAS).

METHODS

All participants (135) performed oximetry (WristOx 3100™) and polysomnography (PSG) simultaneously in the sleep laboratory. The patients completed the Epworth sleepiness scale, the Berlin questionnaire, and a clinical history. Two blind independent observers decided to prescribe CPAP according to the results of the PSG (gold standard, observer A), oximetry (alternative method, observer B), and the clinical parameters. The accuracy of observer B on the indication of CPAP, using different cutoff points of the adjusted desaturation index (ADI3 and ADI4), was evaluated by the area under the receiver operating characteristics curve (AUC-ROC). The interobserver agreement for the indication of CPAP was assessed using kappa statistics.

RESULTS

One hundred nineteen subjects were included (92 men; mean age, 53; median respiratory disturbance index, 22.6; median BMI, 27.5 kg/m(2)). Depending on the criteria used in oximetry, the sensitivity and specificity of observer B to initiate a CPAP trial ranged from 79.8% to 92.5% and of 92% to 96%, respectively. The best performance for the indication of CPAP was noted with the adjusted O(2) desaturation index ≥ 3% (AUC-ROC, 0.923). The inter-rater agreement for the prescription of CPAP was good (kappa, 0.60 to 0.79).

CONCLUSION

This simulated study has shown that the use of oximetry plus clinical data has made it possible to indicate CPAP reliably in nearly 90% of the population with OSAS.