The Pediatric Narcolepsy Severity Scale is Useful in Clinical Practice

The Pediatric Narcolepsy Severity Scale (NSS-P) is a valuable tool to measure narcolepsy symptoms in school-aged children and adolescents, according to study results published in Neurology.

Narcolepsy type 1 (NT1) is a disabling neurologic disorder secondary to an irreversible destruction of hypothalamic orexin/hypocretin neurons. In the absence of curative treatments, the management of these patients remains only symptomatic. A previous study validated the NSS, a 15-item self-report questionnaire, in adults with NT1.

The pediatric version of NSS (NSS-P) was developed in order to assess the frequency, severity, and consequences of NT1 symptoms in children and adolescents. The NSS-P assesses the 5 key symptoms of narcolepsy, including excessive daytime sleepiness, cataplexy, hallucinations, sleep paralysis, and disrupted nighttime sleep. After removal of the item about driving, the total score of 14-item NSS-P ranged from 0 to 54.

The objective of the current study was to validate the new score and to assess its responsiveness to treatment.

The study population included 209 patients aged 6 to 17 years old (41.15% girls; mean age, 13.27 years) with NT1 from 2 National Reference Centers for Orphan Hypersomnolence Disorders in France. Of these, 160 patients completed the questionnaire, including 65 children and adolescents who completed it again during the follow-up: 33 patients untreated the first time and under medication the second time, and 32 patients on the same treatment in both occasions.

The psychometric properties of NSS-P, its internal consistency, content validity, reproducibility and responsiveness to pharmacological treatment were satisfactory.  The questionnaire was shown to be a reliable tool to assess NT1 symptoms severity and their consequences, and to detect clinically significant changes under medication in children who were at least 10 years old.

Factor analysis indicated a 4-factor solution with good reliability, including 4 questions on sleep paralysis and hallucinations, 5 questions on daytime sleepiness, 3 questions on cataplexy, and 2 questions on the refreshing effect of a sleep attack and on nighttime sleep.

The NSS-P total score was lower in the group of 92 treated patients, compared with the group of 68 untreated patients (mean score, 23.32 vs 27.03, respectively; mean difference, 3.71).

NSS-P total score was divided in 4 equal ranks to define different severity levels: 0 to 14 (mild; 13%), 15 to 28 (moderate; 54%), 29 to 42 (severe; 29%), and 43 to 54 (very severe; 4%). The percentage of patients in the severe/very severe groups was higher in the untreated compared with the treated group (41% and 26%, respectively, P =.02).

The chances of having self-reported excessive daytime sleepiness increased with the NSS-P score in both groups. The NSS-P total score was significantly associated with other self-reported assessments of sleepiness, fatigue, insomnia, and depressive symptoms.

The study had several limitations, including lack of data on the reliability of the NSS-P in children younger than 10 years old as these patients were excluded from the study, missing data on self-reported rating scales, and relatively small sample size to assess the effect in various subgroups.

“[W]e validated a brief instrument to assess NT1 symptom frequency, severity and consequences in ≥10-year-old children and adolescents, with four clinically relevant severity score ranges. This scale constitutes a relevant tool to improve and provide guidance for NT1 management in pediatric populations. The ease of administration, its good psychometric properties, and its sensitivity to detect symptom changes after treatment ensure NSS-P future use in clinical and research settings, “concluded the study researchers.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference

Barateau L, Lecendreux 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