Nafamostat mesylate (NM) is increasingly used as an alternative anticoagulant during continuous venovenous hemodiafiltration (CVVHDF) in pediatric intensive care, especially when unfractionated heparin or regional citrate is contraindicated. However, evidence regarding optimal monitoring of its anticoagulant effects remains limited. This study aimed to investigate the association between NM infusion rate and coagulation parameters—specifically activated clotting time (ACT) and activated partial thromboplastin time (aPTT)—in critically ill pediatric patients receiving CVVHDF, and to examine how hepatic function and transfusion status may influence this relationship. In this retrospective study of 99 patients, we analyzed 340 matched data pairs of NM infusion orders and coagulation test results. Linear mixed-effects models revealed a significant positive correlation between NM infusion rate and aPTT (β = 8.54, P < 0.001), while no significant association was found with ACT. Subgroup analyses stratified by liver function and transfusion status consistently supported the association between NM and aPTT. Non-linear regression further suggested a dose–response pattern for aPTT, but not for ACT. These findings indicate that aPTT may be a more sensitive and reliable parameter than ACT for monitoring NM’s anticoagulant effects in pediatric CVVHDF. The results challenge current ACT-based monitoring practices and highlight the need for prospective validation to refine anticoagulation strategies using NM in critically ill children.

Background: Kawasaki disease (KD) is an acute type of vasculitis in children, with coronary artery aneurysm (CAA) being its most serious complication. Intravenous immunoglobulin (IVIg) with acetylsalicylic acid (ASA) is the standard treatment, but concerns about IVIg’s availability and adverse effects have led to interest in corticosteroids (CSs) as an alternative. This study compares the clinical outcomes of IVIg and CSs in KD patients. Methods: Using South Korean Health Insurance Review and Assessment Service (HIRA) data from 2017 and 2020, we identified children under five diagnosed with KD and treated with IVIg and ASA (the IVIg group) or CSs and ASA (the CS group). Propensity score weighting was applied. The primary outcome was the incidence of CAA, and the secondary outcome included cardiovascular complications. Cox proportional hazards models were used to estimate the hazard ratios (HRs) with 95% confidence intervals (CIs). Results: After adjustment, the CAA incidence was higher in the CS group (6.72%) than in the IVIg group (1.86%) (HR = 3.70; 95% CI: 1.96–6.97; p < 0.0001). Cardiovascular complications were also more frequent in the CS group (HR = 2.87; 95% CI: 1.96–6.97; p < 0.0001). Conclusions: The combination treatment, of CSs and ASA, was associated with a higher risk of CAA and cardiovascular complications compared to that when using IVIg in pediatric KD patients. While CSs may be beneficial as an adjunct therapy in IVIg-resistant cases, they should not replace IVIg as a first-line treatment. Alternative strategies, such as reduced-dose IVIg with adjunctive therapies, should be explored.