Validation of the pediatric stroke outcome measure for classifying overall neurological deficit

Background The pediatric stroke outcome measure (PSOM) is a standardized, disease-specific outcome measure. We aimed to validate the overall classification of neurological deficit severity using PSOM. Methods We identified 367 neonates/children with arterial ischemic stroke (AIS) (Derivation Cohort). We analyzed the PSOM subscales (scored as 0 [no deficit], 0.5 [minimal/mild deficit; normal function], 1 [moderate deficit; slowing function], or 2 [severe deficit; missing function]) to derive severity levels using latent class analysis (LCA). We validated a severity classification scheme (PSOM-SCS) in: (a) children who had Pediatric Evaluation of Disability Inventory (PEDI; n = 63) and/or the Pediatric Quality-of-Life Inventory (PedsQL; n = 97) scored; and (b) an external cohort (AIS; n = 102) with concurrently scored modified Rankin Scale (mRS), King’s Outcome Scale for Childhood Head-Injury (KOSCHI) and PSOM. Results Within the Derivation Cohort, LCA identified three severity levels: “normal/mild,” “moderate,” and “severe” (83.7%, 13.3%, and 3%, respectively). We developed severity classification based on PSOM subscale scores: “normal/mild”—normal function in all domains or slowing in one domain, “moderate”—slowing in ≥2 domains or missing function in one domain, and “severe”—missing function in ≥2 domains or slowing in ≥1 plus missing in one domain. PEDI and PedsQL both differed significantly across the severity groups. PSOM-SCS displayed high concordance with mRS (agreement coefficient [AC2] = 0.88) and KOSCHI (AC2 = 0.79). Conclusion The PSOM-SCS constitutes a valid tool for classifying overall neurological severity emphasizing function and encompassing the full range of severity in pediatric stroke. Impact Arithmetic summing of the PSOM subscales scores to assess severity classification is inadequate. The prior severity classification using PSOM overestimates poor outcomes. Three distinct severity profiles using PSOM subscales are identified. The PSOM-SCS is in moderate to excellent agreement with other disability measures. PSOM-SCS offers a valid tool for classifying the overall neurological deficit severity.