Chinese version of narcolepsy severity scale: a validation study

BACKGROUND: The narcolepsy severity scale (NSS) was developed to measure the severity and consequences of symptoms in patients with narcolepsy. The scale has been validated in France, though no other studies have further validated this instrument. The current study aimed to present psychometric properties and describe the score distribution of the Chinese-NSS. METHODS: One hundred twenty-two patients with narcolepsy (41 females and 81 males; mean age 26.14 ± 15.40 years) participated in the study. All patients completed the Chinese-NSS. Cronbach’s α, item-total score correlations, exploratory factor analysis (EFA), and correlations between NSS total scores and clinical or sleep parameters were then calculated. RESULTS: EFA yielded a three-factor model. Internal consistency was acceptable (Cronbach’sα = 0.799). The NSS total score had significant correlations with the Epworth sleepiness score (0.447), pediatric daytime sleepiness scale (0.318), the insomnia severity index (0.592), Beck depression inventory (0.593), EurQol five dimensions-utility (0.457), EurQol five dimensions -VAS (− 0.323), the sleep disturbance scale for children (0.440), the children depression inventory (0.553), and the pediatric quality of life inventory (0.555) total scores, demonstrating acceptable convergence as predicted. CONCLUSIONS: The current study is the first validation study of the narcolepsy severity scale in an Asian population. The findings validated the Chinese-narcolepsy severity scale in a Chinese population with acceptable psychometric properties. There are minor differences between our results and those of the original study due to cultural differences.