Is the Nox-T3 device scoring algorithm accurate enough for the diagnosis of obstructive sleep apnea?

Introduction: Obstructive sleep apnea (OSA) is highly prevalent. Home sleep apnea testing (HSAT) for OSA is rapidly expanding because of its cost effectiveness in the diagnosis of OSA. Type 3 portable monitors are used for this purpose. In most cases, these devices contain an algorithm for automatic scoring of events. We propose to study the accuracy of the automatic scoring algorithm in our population in order to compare it with the manually edited scoring of Nox-T3®.

Material And Methods: For five months, a prospective study was performed. Patients were randomly distributed to the available HSAT devices. We collected the data of patients who performed HSAT with Nox-T3®. We used normality plots, the Spearman correlation, the Wilcoxon signed-rank test, and Bland-Altman plots.

Results: The sample consisted of 283 participants. The average manual apnea and hypopnea index (AHI) was 23.7 ± 22.1 events/h. All manual scores (AHI, apnea index, hypopnea index, and oxygen desaturation index) had strong correlations with their respective automated scores. When AHI > 15 and AHI > 30 the difference between the values of this index (automatic and manual) was not statistically significant. Also, for AHI values > 15 the mean difference between the two scoring methods was 0.17 events/h. For AHI values > 30, this difference was - 1.23 events/h.

Conclusions: When AHI is < 15, there may be a need for confirmation of automatic scores, especially in symptomatic patients with a high pretest probability of OSA. But, for patients with AHI > 15, automatic scores obtained from this device seem accurate enough to diagnose OSA in the correct clinical setting.