Korean J Otorhinolaryngol-Head Neck Surg.  2021 Jul;64(7):479-485. 10.3342/kjorl-hns.2020.00115.

Assessment of the Test-Retest Reliability of Level III Polysomnography: Comparison of Results Using Difference of Apnea-Hypopnea Index Score and Severity of Obstructive Sleep Apnea

  • 1Department of Otorhinolaryngology-Head and Neck Surgery, Inje University College of Medicine, Ilsan Paik Hospital, Goyang, Korea


Background and Objectives
Although studies of test-retest reliability of the standard polysomnography has been reported numerous times, studies of portable sleep devices have been reported in very few cases to date. The purpose of this study is to investigate the test-retest reliability of level III devices, to examine the characteristics of patients with tendency of underestimation and to determine whether there are factors that can predict when retest is needed.
Subjects and Method
We enrolled 74 patients for this study from April 2014 to March 2019. Two indicators were used to assess night to night variability. If the difference of apneahypopnea index (AHI) score was less than 10 or there is no difference of severity of obstructive sleep apnea (OSA) between two nights, we decided that the results have a reliability.
Seventeen out of 57 patients with an AHI difference of less than 10 showed unreliable results based on severity, and 3 out of 17 patients with the AHI difference more than 10 showed reliable results based on severity. Eight out of 74 patients were diagnosed at Night 2 but not at Night 1. In other words, about 11% of the subjects needed retest. Based on the change in severity of OSA, subjective sleep scores showed a statistically significant difference, indicating that the subjective sleep score should be considered when deciding a retest. AHI differed by more than 10 in about 23% of the subjects in this study, falling within “15%- 32%,” which has been reported in the literature on the level I test.
This suggests that there is no significant difference in reliability between level I and III.


Polysomnography; Reproducibility of results; Sleep apnea, obstructive
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