Psychometric Properties of the Pediatric Acute-Onset Neuropsychiatric Syndrome Global Impairment Score in Children and Adolescents with Pediatric Acute-Onset Neuropsychiatric Syndrome.

Objectives: This study validates the caregiver-rated Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) Global Impairment Score (GIS), a single-item, 0-100 scale, for use in PANS. Methods: We collected longitudinal data from community patients meeting PANS criteria. We included 128 patients with 1926 GISs, each from a unique clinic visit. To assess discriminant validity, we compared GISs from patients with PANS with scores from a population of healthy controls. To evaluate external validity, we compared global impairment with a clinician-reported global measurethe Child Global Assessment Scale (CGAS)using the Bland-Altman plots and correlation coefficients. Then, we evaluated associations between the PANS GIS and symptom-specific disease severity variables by fitting mixed models with repeated measures. Results: The GIS shows excellent discriminant validity, distinguishing patients with PANS from healthy controls. The scores on the GIS show an acceptable level of agreement with the clinician-reported CGAS. The regression line in the Bland-Altman plot had a positive slope, indicating that parents tend to report higher disease severity than clinicians at higher levels of disease severity. Correlation was higher during disease remissions than during disease flares (r=-0.69 vs. r=-0.48). All disease severity scales predicted GIS in the expected direction. Conclusion: The GIS has excellent discriminant validity and acceptable construct validity.