Trends and disparities in NIHSS reporting and outcomes in acute ischemic stroke hospitalizations: A retrospective cross-sectional study

BACKGROUND: The National Institutes of Health Stroke Scale (NIHSS) quantifies stroke severity, yet variability in its reporting may reflect healthcare disparities and affect outcomes. This study analyzes trends in NIHSS reporting in the National Inpatient Sample (NIS) database and its relationship with patient characteristics and outcomes. METHODS: This retrospective cross-sectional study used data from the NIS between May 2016 and December 2022. This nationally representative sample included patients in the US hospitalized with acute ischemic stroke (AIS). Primary outcomes include NIHSS reporting rate over time, factors associated with reporting, and subsequent discharge disposition. Propensity score matching (PSM) accounted for patient demographics, hospital characteristics, severity of illness, and use of reperfusion therapy. RESULTS: Among 4,558,909 AIS hospitalizations, NIHSS was reported in 1,930,880 (42.4%). The proportion of hospitalizations with reported NIHSS increased from 14.33% in December 2016 to 56.27% in December 2022. After PSM, reporting of NIHSS was associated with higher odds of routine discharge (Adjusted Odds Ratio = 1.03, 95% CI: [1.01-1.04]; p < 0.001) and lower odds of inpatient mortality (0.650 [0.632-0.668], p < 0.001). Scores were less likely to be reported in females (0.970 [0.961-0.979], p < 0.001) and Black (0.963 [0.939-0.988], p = 0.004) or Hispanic patients (0.960 [0.926-0.996], p = 0.030), as well as in smaller and less urban hospitals. DISCUSSION: Since the implementation of NIHSS reporting, rates have increased to more than half of all AIS hospitalizations as of December 2022. NIHSS reporting was significantly associated with improved discharge disposition, and patient demographics impacted odds of having a reported NIHSS, highlighting persistent disparities in stroke care.