Abstract 2484: Validity and Reliability of Retrospective Scoring of the Pediatric NIH Stroke Scale

Background and Objectives: The Pediatric National Institutes of Health Stroke Scale (PedNIHSS), an adaptation of the adult NIH Stroke Scale, is a quantitative measure of stroke severity shown to be reliable when scored prospectively. The ability to calculate the PedNIHSS score retrospectively would be invaluable in the conduct of retrospective pediatric stroke studies. To this end, the objective of this study was to assess the validity and reliability of calculating the PedNIHSS score retrospectively from medical records. Methods: Neurological examinations documented in medical records of 75 children from 9 institutions were deidentified and photocopied. All subjects had been previously enrolled in a prospective PedNIHSS validation study. Four neurologists of varying clinical training levels were given detailed instructions on how to translate the neurological examination into a PedNIHSS score. If an item was not recorded in the medical record, it was scored as 0 (normal) as was done in past adult studies. The raters were blinded to the PedNIHSS scores derived from the prospective study, reviewed the documented neurological examinations, and retrospectively assigned the PedNIHSS score. Each rater scored the 75 patients' examinations in the same order. Retrospective scores were compared among raters and to the prospectively measured scores. Results: The mean prospective total PedNIHSS score for the 75 subjects was 8.2 (SD 7) with median 6 (IQR 3-12).The mean total retrospective PedNIHSS score was 7.6 (SD 7) with median 5 (IQR 3-11). The mean and median total prospective and retrospective PedNIHSS scores were not significantly different (p= 0.49 Student's t-test; p=0.37 Wilcoxon rank-sum). Total retrospective PedNIHSS scores correlated highly with prospectively assigned total scores (R 2 0.76, p<0.001). Eighty-nine percent of retrospective total scores were within 5 points of the prospectively scored totals. Using a pre-determined threshold PedNIHSS score ≤5, the sensitivity of retrospective assessment was 87% (95% CI: 81-92%) and the specificity was 81% (95%CI: 74-87%). Interrater reliability for the total retrospective scores among the four raters assessed with the intraclass correlation coefficient was 0.95 (95% CI: 0.94-0.97). Interrater reliability for the 15 item scores that comprise the total PedNIHSS score, assessed with weighted κ, ranged from 0.47 to 0.93. Interrater reliability for all but one item was “substantial” or “excellent.” Conclusions: The PedNIHSS score can be assessed retrospectively from medical records with a high degree of validity and reliability. This tool, a stroke severity measure, can be used to improve the quality of retrospective pediatric stroke studies.