title: Diagnostic accuracy of split-night polysomnograms.
abstract: OBJECTIVE
  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 > or = 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 (2 hr-AHI) and 3 hours (3 hr-AHI) of sleep with the "gold standard" AHI from FN-PSG (FN-AHI), considering OSA present if FN-AHI > or = 5.
  
  
  RESULTS
  The 2 hr-AHI and 3 hr-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 2 hr-AHI and 3 hr-AHI using FN-AHI > or = 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 > or = 20 to 40) may be revised to a lower number, allowing for more efficient use of resources.
authors: Center for Sleep Medicine, Mayo Clinic, Rochester, MN 55905, USA.
authors: Imran S
authors: IS
authors: Khawaja
authors: Eric J
authors: EJ
authors: Olson
authors: Christelle
authors: C
authors: van der Walt
authors: Jan
authors: J
authors: Bukartyk
authors: Virend
authors: V
authors: Somers
authors: Ross
authors: R
authors: Dierkhising
authors: Timothy I
authors: TI
authors: Morgenthaler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods* / Q000592:standards; D012015:Reference Standards; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012737:Sex Factors; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult