Initial validation of a pediatric cataplexy survey for children and adolescents with narcolepsy type 1.

PURPOSE: 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 to guide care. In this study, we developed and validated a 7-item Pediatric Cataplexy Scale (PCS). 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. Current knowledge/Study rationale Cataplexy is a core symptom of pediatric narcolepsy type 1, yet no validated tool exists to measure its frequency, severity, and impact in children and adolescents. This gap limits clinicians’ ability to assess symptom burden and guide treatment. Study impact In this study, we developed and validated the 7-item Pediatric Cataplexy Scale (PCS) using rigorous item response theory methods across a multi-site NT1 cohort. The PCS demonstrated strong internal consistency, excellent model fit, and appropriate convergent, divergent, and sex-invariant properties, supporting its reliability and validity. This scale offers the first psychometrically robust cataplexy measure to use in youth with NT1, enabling standardized symptom assessment in both clinical care and research.