title: Narcolepsy and predictors of positive MSLTs in the Wisconsin Sleep Cohort.
abstract: OBJECTIVE
  To study whether positive multiple sleep latency tests (MSLTs, mean sleep latency [MSL] ≤ 8 minutes, ≥ 2 sleep onset REM sleep periods [SOREMPs]) and/or nocturnal SOREMP (REM sleep latency ≤ 15 minutes during nocturnal polysomonography [NPSG]) are stable traits and can reflect incipient narcolepsy.
  
  
  METHODS
  Cross-sectional and longitudinal investigation of the Wisconsin Sleep Cohort Study.
  
  
  METHODS
  Adults (44% females, 30-81 years) underwent NPSG (n = 4,866 in 1,518 subjects), and clinical MSLT (n = 1,135), with 823 having a repeat NPSG-MSLT at 4-year intervals, totaling 1725 NPSG with MSLT studies. Data were analyzed using linear mixed-effects models, and the stability of positive MSLTs was explored using κ statistics.
  
  
  RESULTS
  Prevalence of a nocturnal SOREMP on a NPSG, of ≥ 2 SOREMPs on the MSLT, of MSL ≤ 8 minutes on the MSLT, and of a positive MSLT (MSL ≤ 8 minutes plus ≥ 2 SOREMPs) were 0.35%, 7.0%, 22%, and 3.4%, respectively. Correlates of a positive MSLT were shift work (OR = 7.8, P = 0.0001) and short sleep (OR = 1.51/h, P = 0.04). Test-retest for these parameters was poor, with κ < 0.2 (n.s.) after excluding shift workers and short sleepers. Excluding shift-work, short sleep, and subjects with negative MSLTs, we found one undiagnosed subject with possible cataplexy (≥ 1/month) and a NPSG SOREMPs; one subject previously diagnosed with narcolepsy without cataplexy with 2 NPSG SOREMPs and a positive MSLT, and two subjects with 2 independently positive MSLTs (66% human leukocyte antigen [HLA] positive). The proportions for narcolepsy with and without cataplexy were 0.07% (95% CI: 0.02-0.37%) and 0.20% (95% CI: 0.07-0.58%), respectively.
  
  
  CONCLUSIONS
  The diagnostic value of multiple sleep latency tests is strongly altered by shift work and to a lesser extent by chronic sleep deprivation. The prevalence of narcolepsy without cataplexy may be 3-fold higher than that of narcolepsy-cataplexy.
authors.affiliation: Department of Pediatrics and Sleep Wake Disorders Unit, Faculty of Health Sciences, Ben Gurion University, Soroka University Medical Center, Beer Sheva, Israel ; Center for Sleep Sciences and Medicine, and Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Aviv
authors.initials: A
authors.lastname: Goldbart
authors.affiliation: Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI.
authors.forename: Paul
authors.initials: P
authors.lastname: Peppard
authors.affiliation: Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI.
authors.forename: Laurel
authors.initials: L
authors.lastname: Finn
authors.affiliation: Center for Sleep Sciences and Medicine, and Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Chad M
authors.initials: CM
authors.lastname: Ruoff
authors.affiliation: Department of Pediatrics and Sleep Wake Disorders Unit, Faculty of Health Sciences, Ben Gurion University, Soroka University Medical Center, Beer Sheva, Israel.
authors.forename: Jodi
authors.initials: J
authors.lastname: Barnet
authors.affiliation: Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI.
authors.forename: Terry
authors.initials: T
authors.lastname: Young
authors.affiliation: Center for Sleep Sciences and Medicine, and Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mignot
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002385:Cataplexy / Q000175:diagnosis / Q000503:physiopathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000175:diagnosis* / Q000503:physiopathology*; D017286:Polysomnography; D015995:Prevalence; D012892:Sleep Deprivation; D020178:Sleep Disorders, Circadian Rhythm; D012895:Sleep, REM / Q000502:physiology*; D013997:Time Factors; D014922:Wisconsin
keywords: HLA; MSLT; REM sleep; cataplexy; narcolepsy; polysomnography