Since its creation in 1977, the multiple sleep latency test (MSLT) has been extensively used as a diagnostic tool for patients suspected of having narcolepsy and idiopathic hypersomnia.
Sometimes sleep practitioners encounter situations in which the results of the MSLT are not clear and recommend a retest, especially when they want to confirm a diagnosis such as narcolepsy. This phenomenon is rather common, especially since researchers like Thomas Scammell, MD, have noted that MSLTs can easily give false positives and negatives when conducted without a strict testing protocol. But a new study suggests that the results of a carefully controlled MSLT are enough to be considered accurate without the need for a retest. The study is published in the SLEEP 2016 abstract supplement (page 245).
“This is the first type of study of its kind that really took a hard look at the MSLT’s retest reliability in a consecutive day-to-day setting,” says lead investigator, Younghoon Kwon, MD, who is also an assistant professor of cardiovascular medicine and sleep medicine at the University of Virginia Health System. “In several clinical settings we found ourselves questioning whether we should repeat this expensive test [MSLT] because we weren’t sure of the validity and accuracy of the results of a previously done MSLT.”
So Kwon and others looked at the MSLT results of a group of patients who complained of having persistently severe hypersomnia and who also underwent two in-lab consecutive MSLTs. Results of the study revealed that the day-to-day variability between the results of two consecutively conducted MSLTs to be low.
“The take home message of this study for practitioners is that generally speaking when a patient undergoes MSLT after following a strict standard protocol, then one MSLT should be sufficient enough for an accurate diagnosis,” says Kwon.
This is true as long as the MSLT testing protocol includes measures to control factors that may affect the results of the test, such as the amount of sleep a patient gets prior to the study.
An example of a strict standard protocol, according to Kwon, is one that involves: requiring that a patient keeps a sleep diary or wears an actigraph unit for two weeks to ensure that he or she is getting an adequate amount of sleep, requiring that a patient discontinues the use of stimulants and antidepressants, and requiring that a patient undergo an overnight sleep study prior to the day of the MSLT.
“From a clinical perspective, this study shows that you don’t need to repeat the MSLT a day after the first just because you’re a bit doubtful. As long as you’re assured that you did your best and the patient has done his or her best to follow proper sleep study protocols, then there’s no need to repeat the assessment.”
Kwon adds he hopes that the findings of this study reinforce the need for a carefully implemented MSLT protocol that’s consistent in a way that repeated testing is not needed.
Glad to hear that; as I think the test itself is absolutely devastating to people with narcolepsy. I almost couldn’t complete it, it actually may have been one of the worst days of my life. And then the repercussions of it took a toll on me for another week.
Agreed. The test was dreadful and significantly challenging for me…it felt a bit like torture. It’s good to know that repeating it doesn’t make sense as long as the appropriate protocol was followed for the initial test.
Spend any significant length of time in any of the online support groups for N or IH and it will quickly become apparent that in practice the percentage MSLTs in which a “strict standard protocol” is followed approaches zero.
Perhaps it would be beneficial for some person or organization to publish, promote and teach a standard protocol because right now that is not happening from clinic to clinic, doctor to doctor, patient to patient or MSLT to MSLT.
Like this one? http://www.aasmnet.org/Resources/PracticeParameters/PP_MSLTMWT.pdf
Yes exactly like that one (or more accurately the document it references, “Guidelines for the Multiple Sleep Latency Test (MSLT): a Standard measure of sleepiness”). It’s the promote and teach part that’s not happening with those standards.
I have no idea why those standards are not used and can subsequently offer no suggestions beyond ‘promote and teach’. If it’s not possible to achieve adoption with the existing documents, perhaps new documents should be published.