NIHSS Discrepancy and Reliability in Stroke Triage

Abstract The National Institute of Health Stroke Scale (NIHSS) is the standard metric in both clinical practice and stroke research used to establish a baseline in patients suffering from an acute ischemic stroke (AIS). The initial score severity during triage has direct impact in guiding the appropriate treatment. In this study, we sought to examine the reliability of the NIHSS when scored by neurology clinicians versus emergency department (ED) clinicians. NIHSS scores were obtained from 1092 patients being evaluated for AIS at Houston Methodist Hospital from 05/2016 – 04/2018. The initial (baseline) NIHSS score was obtained from the clinical documentation of the neurology and ED providers. Patients were only included if the treatment status was the same (pre-treatment, post-treatment, or no treatment) and if there was no significant time delay between the recorded scores (<1 hour). 142 patients were ultimately included for analysis. The distribution of the NIHSS score difference (neurology score – ED score) had a mean of 0.827 and standard deviation of 2.901. The intraclass correlation coefficient for total score was 0.91 (95% CI, 0.87 - 0.94). Reliability was excellent between the groups with no significant difference between the NIHSS scores. There were 7 outliers (4.93%) with >5 difference in the NIHSS scores. These were individually examined, and most were found to result from improper NIHSS scoring in the ED (incongruity between the ED clinical exam findings and reported NIHSS score). In hospitals and EDs where a stroke trained neurology clinician is not available, the reliability of the triage NIHSS score from the ED provider is paramount in establishing the patient baseline and guiding treatment.