The Clinical Utility of a Novel Pediatric Narcolepsy Scale

Lucie Barateau, MD

Newly published data from a cohort of more than 150 children and adolescents with narcolepsy type 1 (NT1) suggest that the novel Pediatric Narcolepsy Severity Scale (NSS-P), reformulated from the original NSS for a younger group, might be a useful tool for sleep specialists, neurologists, and other physicians offering care to this population. All told, the tool was associated with self-reported sleepiness, insomnia, and depressive symptoms among school-aged children and adolescents.

All participants included were diagnosed in 3 Reference Centers for Narcolepsy in France and were consecutively asked to fill in the NSS-P. In total, 160 (age range, 10-18 years) individuals completed the NSS-P. The investigators had 65 participants complete the scale twice (33 before/during treatment and 32 under the same treatment). The NSS-P psychometric properties, score changes before/during treatment, and convergent validity with other clinical parameters were also assessed by the group.

NeurologyLive spoke with Lucie Barateau, MD, assistant professor of neurology, Hôpital Gui de Chauliac, an investigator on the study, to learn more about the findings, about this scale’s current form, and its potential usefulness in the clinic.

NeurologyLive: What should the clinical community take away from this work, and how vital is a pediatric version of the NSS for clinical practice?

Lucie Barateau, MD: This work provides for the first time the validation of a scale to assess and monitor NT1 symptoms in children population. Its ease of administration, good psychometric properties, and sensitivity to detect symptom changes after treatment can ensure its use in clinical and research settings.

A pediatric version of NSS was, really, mandatory. So far, a comprehensive tool that quantifies all NT1 symptoms in children was seriously lacking. Sleepiness scales were used together with a daily diary to capture cataplexy frequency, but NT1 is a lifelong and disabling sleep disorder that really needed specific evaluation tools.

What did your assessment show and were any of the findings surprising regarding the scale’s measures or use?

In this paper, we showed that the NSS-P has adequate psychometric properties and a good temporal stability. The total score ranges from 0 to 54 (higher scores reflecting more severe symptoms), and is associated with self-reported sleepiness, insomnia, and depressive symptoms. It has 4 severity levels: mild 0-14, moderate 15-28, severe 29-42, and very severe 43-54. The score is lower in treated than untreated patients, with a minimum clinically important difference at 4 points.

The NSS, which is validated in adults, was reformulated for children with adapted wording, but the scale turned out to be unreliable in the youngest children (those younger than 10 years old). This result is probably explained not by the scale itself, but because young children have problems in correctly recognizing and quantifying their symptoms, especially cataplexy. However, the scale could still be used in younger children, depending on their maturity and their parents’ help in completing it.

Are there any remaining improvements that could be made to this scale and its use?

The original NSS-P questionnaire was validated in French and translated into English with the help of the MAPI Research Institute, which hosts and distributes the scale and provides a central clearinghouse for all current and future copyrighted translations. The NSS for adults was recently validated in other languages; the same could be done for NSS-P. The scale can be completed in 5 minutes. We advocate for its wide use in all sleep centers and by all physicians managing children with NT1.

At last, it is important to notice that other symptoms that may occur in NT1—such as fatigue, attention disorders, brain fog, or automatic behaviors, for instance—and comorbid conditions—like obesity, depressive symptoms, anxiety, and parasomnias—are not evaluated by our questionnaire. Additional research could develop patient-reported outcome measures to capture these aspects in pediatric NT1.

Transcript edited for clarity.

REFERENCES
1. Barateau L, Lcendreux M, Chenini S, et al. Measurement of Narcolepsy Symptoms in School-Aged Children and Adolescents: The Pediatric Narcolepsy Severity Scale. Neurology. Published online May 24, 2021. doi: 10.1212/WNL.0000000000012272