Development and validation of the narcolepsy severity scale in school aged children

Abstract

Objective: To develop and psychometrically test the pediatric narcolepsy severity scale (P-NSS) for pediatric with narcolepsy type 1 (NT1).

Methods: Item pool was formed based on literature review, clinical judgement of the expert panel and input of the narcoleptic patients and their parents. Psychometric properties were evaluated after applying the P-NSS in a sample of 200 patients (8-18 years age) with narcolepsy. Analyses included item analysis, validity analysis and reliability analysis.

Results: P-NSS consisted four factors with a total of 17 items. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) revealed four distinct and theoretically coherent factors, explaining 63.4% of the total variance. The fitting results of the CFA model were χ2/dƒ = 2.235, GFI = 0.876, AGFI = 0.822, RMSEA = 0.079, TLI = 0.908, CFI = 0.927. P-NSS score is correlated with Pediatric Daytime Sleepiness Scale (r = 0.512, P < 0.01), Epworth Sleepiness Scale for Children and Adolescents (r = 0.355, P < 0.01) and Narcolepsy quality-of-life instrument with 21 questions (r = -0.512, P < 0.01). Cronbach's α coefficient for P-NSS and four dimensions were from 0.732 to 0.915. The split-half reliability was 0.882 (P < 0.01).

Conclusion: P-NSS is proved to be a reliable and valid measure for Chinese children with NT1. It may serve in China as a valuable and easily accessible outcome measure for using in narcolepsy trials, the clinic with improved responsiveness and long term follow-up.

Keywords: Narcolepsy; Pediatrics; Reliability; Validity.