Prognostic Value of International Normalized Ratio and Thrombocytopenia in Early Risk Stratification of Septic Patients

Background/Objective: Coagulopathy is a hallmark of sepsis, associated with poor outcomes. Although platelet count has commonly been used for risk stratification, its prognostic value has remained limited. This study compared the ability of the International Normalized Ratio (INR) and platelet count to predict in-hospital mortality in septic patients; Methods: A retrospective study was conducted including adult patients diagnosed with sepsis and admitted to Hospital Universitario Son Llàtzer (Spain) between 2006 and 2022. The INR and platelet count at diagnosis were categorized using clinical thresholds. The primary outcome was in-hospital mortality. Results: Among 6433 patients (60.6% females), mortality was 8.8%. Mortality increased from 6.3% (INR ≤ 1.2) to 20.2% (INR 2.0–3.0), slightly decreasing at INR > 3.0 (10.8%). The platelet count showed a weaker association, with the highest mortality observed at 3.0 and platelet count < 50 × 109/L). In the full cohort, multivariable analysis confirmed the INR as an independent predictor of mortality (OR 2.183, p = 0.0002), whereas the platelet count was not significant. The model including the INR achieved an AUC 0.746, while adding the platelet count did not improve performance. Conclusions: the INR at diagnosis was a strong and independent predictor of in-hospital mortality, outperforming the platelet count. These findings could support the consideration of the INR in early risk stratification frameworks and highlight the need for prospective validation before integration into sepsis guidelines.