Discharge NIHSS scores are predictive of poor 3-month outcomes in patients with acute Ischemic stroke receiving intravenous thrombolysis

While early National Institutes of Health Stroke Scale (NIHSS) scores are predictive of outcomes in patients with acute ischemic stroke (AIS), the prognostic value of the discharge NIHSS score after intravenous thrombolysis (IVT) remains unclear. We aimed to determine whether the discharge NIHSS score outperforms baseline, 24-hour, and early change indicators in predicting poor 3-month outcomes (modified Rankin scale [mRS] score of 3–6). In this retrospective cohort study, we analyzed 554 AIS patients who received IVT at our stroke center from May 2022 to March 2024. NIHSS scores were assessed at baseline, 24 h, and discharge. Absolute (baseline minus discharge) and percentage (absolute change/baseline × 100%) NIHSS changes were calculated. Multivariable logistic regression analyses were used to assess the independent correlation between different NIHSS scores and poor outcomes. Predictive performance was evaluated using receiver operating characteristic (ROC) curves, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Discharge NIHSS scores demonstrated superior discriminative ability for poor outcomes (AUC 0.950, 95% CI 0.932–0.969) versus baseline (AUC 0.842), 24-hour (AUC 0.930), absolute change (AUC 0.689), and percentage change (AUC 0.885) (all p < 0.001). The optimal cutoff was 4.5 (sensitivity 90.5%, specificity 86.0%). Adding the discharge NIHSS score to the 24-hour NIHSS score significantly improved reclassification (NRI 123.4%, IDI 9.1%). The discharge NIHSS score consistently outperformed the 24-hour NIHSS score in predicting poor 3-month functional outcomes across all key patient subgroups. This study revealed a notable association between the discharge NIHSS score and poor 3-month outcomes in thrombolysis-eligible patients with AIS, particularly in those with moderate stroke severity. These findings complement the established prognostic value of the 24-hour NIHSS score and may guide postacute care planning. The discharge NIHSS score is the strongest predictor of poor 3-month functional outcomes in acute ischemic stroke patients receiving intravenous thrombolysis, outperforming baseline, 24-hour, and early change NIHSS metrics (AUC 0.950, optimal cutoff ≥4.5). Incorporating the discharge NIHSS score into prognostic models significantly improves risk stratification (NRI 123.4%, IDI 9.1%), providing additional prognostic information that may improve risk stratification in clinical research and follow-up planning. The study bridges a critical gap in thrombolysis prognostication by demonstrating that discharge NIHSS scores, which capture stabilized deficits and late complications, complement the established predictive value of 24-hour assessments.