Optimizing MSLT specificity in narcolepsy with cataplexy

Abstract

Study Objectives: Multiple sleep onset rapid eye movement (R) periods (SOREMPs) and a mean sleep latency of =8 minutes on the multiple sleep latency test (MSLT) are diagnostic criteria of narcolepsy (NC), but also occur in other conditions with increased sleep pressure, including insufficient sleep syndrome (ISS), sleep-disordered breathing (SDB), or Parkinson’s disease (PD). These false positives are common, may create diagnostic uncertainty, and highlight the need for complementary MSLT measures with high specificity for NC. Methods: Detailed analysis of MSLT findings in 56 NC, 83 PD, 89 SDB, and 23 ISS patients, using receiver operating characteristic curves. Results: A positive MSLT (mean sleep latency = 8.0 minutes and =2 SOREMPs) was found in 53 NC (95%), 1 PD (1%), 8 SDB (9%), and 12 ISS patients (52%). MSLT-based differentiation between NC and non-NC patients was best when applying a mean R latency of =5 minutes (sensitivity/specificity/positive predictive value [PPV]: 49%/95%/96%) or a mean percentage of sleep stage R = 40% (sensitivity/specificity/PPV: 60%/100%/100%) as cutoffs. When analyzing all 252 naps with SOREMPs in isolation, the combination of both R latency of =5 minutes and R percentage of =50% yielded a sensitivity/specificity/PPV of 50%/99%/99%. In addition, a sleep stage sequence with R occurring prior to N2 was more common in NC than in non-NC (71% vs. 32%, p