Abstract Introduction Cataplexy is core symptom of pediatric narcolepsy type 1 (NT1) but there is currently no validated cataplexy scale that captures the frequency, severity, and impact of cataplexy for children and adolescents. In this multi-center study, we developed and validated a 7-item Pediatric Cataplexy Scale (PCS) to further pediatric NT1 clinical care and research. Methods We performed psychometric evaluation of the PCS using item response theory, specifically a graded response model (GRM). Sixty-nine children and adolescents with NT1 (age 9-21) from six North American sites completed the study. We examined the 7-item scale for internal consistency reliability (α, ω, marginal reliability), global and local model fit within the GRM framework, item discrimination and threshold ordering, convergent and divergent validity, and measurement invariance across sex. Results Internal consistency was strong using all three indicators. The freely estimated GRM provided superior fit over a Rasch-constrained model (p=0.032) and excellent global fit indices (CFI=0.996; TLI=0.995; RMSEA=0.041; SRMR=0.041). Convergent validity was supported by significant correlations with the Narcolepsy Severity Scale (r=0.459, p 0.001) and the PedsQL Psychosocial Health Summary Score (r=-0.295, p=0.014). Divergent validity was demonstrated through nonsignificant associations with the respiratory disturbance index and body mass index. Measurement invariance testing showed minimal non-invariance across sex, with no significant differences in latent means. Conclusion The PCS shows desirable psychometric properties and can be used in clinical and research settings to assess cataplexy symptoms in NT1 youth. Support (if any) Wake Up Narcolepsy, Inc. and American Sleep Medicine Foundation grants awarded to KM
Wang et al. (Fri,) studied this question.