Red cell index: A novel biomarker for 3-month mortality in acute ischemic stroke patients treated with intravenous thrombolysis

Background: The red cell index (RCI) was described as a biomarker for evaluating respiratory function in previous studies, but the relationship between RCI and stroke, remained a mystery. The present study aimed to probe the association between RCI at 24-hr and 3-month mortality and functional outcomes among acute ischemic stroke (AIS) patients treated with recombinant tissue plasminogen activator (r-tPA).

Methods: A total of 217 AIS patients between January 2016 and January 2019 were recruited in this retrospective study. AIS patients were grouped in terms of RCI tertiles. Predictive factors were confirmed via multivariate logistic regression analysis. The receiver operating characteristic (ROC) was used to assess the ability of RCI in predicting mortality. In addition, the risk of 3-month all-cause mortality was evaluated by Cox proportional hazard model.

Results: We grouped AIS patients into tertiles with the purpose of comparing clinical factors and RCI levels. Multivariate logistic regression analysis presented that RCI (odds ratio [OR] = 1.443, 95% confidence interval [CI] [1.167-1.786], p = 0.001) was an independent biomarker for 3-month all-cause mortality. The best cutoff value of RCI was 2.41 (area under the curve [AUC] = 0.639, 95% CI [0.501-0.778], p = .032), with a sensitivity of 40.9% and a specificity of 89.7%. Cox survival analysis demonstrated a positive significant correlation between RCI (hazard ratio [HR] = 1.332, 95% CI [1.148-1.545], p < .001) and mortality risk.

Conclusion: RCI, a potential predictor, was significantly associated with 3-month mortality in AIS patients with r-tPA.