Diagnostic accuracy of split-night polysomnograms

Imran S. Khawaja, Eric J. Olson, Christelle Van Der Walt, Jan Bukartyk, Virend Somers, Ross Dierkhising, Timothy I. Morgenthaler

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Study Objectives: American Academy of Sleep Medicine (AASM) practice parameters indicate that split-night polysomnograms (SN-PSG) may be performed when the apnea hypopnea index (AHI) is ≥ 20 to 40, depending on clinical factors. The aim of this study was to determine the diagnostic accuracy of SN-PSG, including at the lower range of AHIs. Methods: We reviewed 114 consecutive full-night PSGs (FN-PSG) performed at our center between August 2006 and November 2008 on subjects enrolled in studies in which obstructive sleep apnea (OSA) was the sleep disorder of interest. We compared the AHI from the first 2 hours (2hr-AHI) and 3 hours (3hr-AHI) of sleep with the "gold standard" AHI from FN-PSG (FN-AHI), considering OSA present if FN-AHI ≥ 5. Results: The 2hr-AHI and 3hr-AHI correlated strongly with the FN-AHI (concordance correlation coefficient [CCC] = 0.93 and 0.97, respectively). After adjusting for percentage of sleep in stage REM sleep and in supine position, the correlation of 2 hr- and 3 hr-AHI with FN-AHI remained strong (0.92 and 0.96, respectively). The area under the receiver operating curves (AUC) for 2hr-AHI and 3hr-AHI using FN-AHI ≥ 5 were 0.93 and 0.95, respectively. Conclusions: The AHI derived from the first 2 or 3 hours of sleep is of sufficient diagnostic accuracy to rule-in OSA at an AHI threshold of 5 in patients suspected of having OSA. This study suggests that the current recommended threshold for split-night studies (AHI ≤ 20 to 40) may be revised to a lower number, allowing for more efficient use of resources.

Original languageEnglish (US)
Pages (from-to)357-362
Number of pages6
JournalJournal of Clinical Sleep Medicine
Issue number4
StatePublished - Aug 15 2010


  • Diagnostic accuracy
  • Obstructive sleep apnea (OSA)
  • Polysomnography (PSG)
  • Split-night polysomnography

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Neurology
  • Clinical Neurology


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