Test–retest reliability of two consecutive mean sleep latency tests in patients with hypersomnia

Abstract

Reliability of mean sleep latency testing (MSLT) over consecutive days in patients with hypersomnia is unknown. We reviewed MSLTs of patients with hypersomnia without cataplexy who underwent our two consecutive MSLT protocol (N=29). Average MSLs were 10.9 and 10.9 minutes for days 1 and 2, respectively. Agreement for pathological hypersomnia (defined as MSL≤8 minutes) between MSLT days showed k=0.85 for all (N=29) and k=0.76 for those without sleep apnea (N=20). In patients with subjective complaints of hypersomnia, a single MSLT is sufficient (vs. addition of 2nd day MSLT) in the setting of carefully implemented protocol controlling for potential confounding variables.

False‐positive cases in multiple sleep latency test by accumulated sleep debt

“…It was reported that the 1st and the 2nd MSLT results with standard procedure were often changed in the subjects with narcolepsy type 2 (=narcolepsy without cataplexy) but not with type 1 (=narcolepsy with cataplexy). 3 , 4 , 5 , 6 Mean sleep latencies of these 2 cases were still <8 minutes. If their sleep latencies were more than 8 minutes, false‐negative results would be made.…”

“…Even for the cases with narcolepsy or idiopathic hypersomnia, their sleep latencies would be extended to more than 8 minutes the longer the hospitalization. Although the comparisons of MSLTs were reported, 3 , 4 , 5 , 6 these studies employed 2 days standard PSG and MSLT procedure with several years interval. On the other hand, our study was conducted to compare MSLTs with 1 night and more than 3 nights.…”

Twice is nice? Test-retest reliability of the Multiple Sleep Latency Test in the central disorders of hypersomnolence

“…Combining data across published studies, repeat MSLT confirms NT1 diagnosis in 91% (68/75) of patients [4][5][6] but only in 45% (26/58) of patients with narcolepsy type 2 (NT2) 1,4-7 and in 49% (21/43) of patients with idiopathic hypersomnia. 1,5,7 Seventy percent of patients with self-reported sleepiness and a normal first MSLT have a normal second MSLT, 1,5,7 and 60% have a normal second MSLT if excluding MSLTs on consecutive days. In patients with NT1, the 8-minute threshold is crossed on only 7% (7/107) of repeat tests, the 2-SOREM threshold on only 10% (12/121) of repeat tests, and both are crossed on 7% (7/107) of repeat tests.…”

“…[4][5][6]8 For NCHD, the 8-minute threshold is crossed on 35% (63/182) of repeat tests, the 2-SOREM threshold on 28% (66/235) of repeat tests, and both on 24% (41/170) of repeat tests. 1,[4][5][6][7][8][9] What explains low retest reliability? Broadly, the possibilities are (1) inadvertent bias introduced by study design, (2) MSLT variability despite stable disease phenotype over time, and (3) disease phenotype variability over time.…”

“…This finding may explain the improved retest reliability with shorter retest intervals, eg, consecutive days vs months or years, even in the same patients. 7 However, across longer intervals, retest reliability remains poor even when excluding medication changes, 1,6 and these other sources of variability should not disproportionately affect those with NCHD.…”