Intravenous Immunoglobulin (IVIG) use in HIT and efficacy of early IVIG compared to standard of care treatment.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is an immune-mediated prothrombotic complication of heparin exposure. Intravenous immunoglobulin (IVIG) has been proposed as an adjunctive therapy for refractory or autoimmune HIT. Real-world utilization patterns and impact of early administration on clinical outcomes remain unclear. METHODS: We performed a retrospective chart review across the Allegheny Health Network (2015-2025). We described clinical characteristics and outcomes among all HIT patients who received IVIG (n=29). We also compared early IVIG recipients (n=24) to controls (n=129) using 1:2 propensity score matching. The primary outcome was time to platelet recovery, analyzed using Kaplan-Meier estimation and Cox proportional hazards regression. RESULTS: IVIG was used in a cohort of patients with a median platelet count nadir of 26 × 109/L (IQR of 16 - 35 ×109/L) and thrombosis was present at diagnosis in 75.8% of patients. Platelet recovery was achieved in 93.1% at a median of 6 days (IQR 3 - 9 Days) days from first dose of IVIG administration, with a favorable safety profile. Early IVIG (within 3 days of HIT diagnosis) was associated with significantly faster platelet recovery in the matched cohort (median 3 vs. 5 days; HR 2.15, 95%CI 1.09-4.26, p=0.028). Higher platelet nadir predicted faster recovery (HR 2.247 per 10 × 109/L, p < 0.001). No significant differences in thrombosis, bleeding, or mortality were observed. CONCLUSIONS: At our institution, IVIG use in HIT was confined to severely ill patients with high thrombotic burden. Early IVIG administration accelerated platelet recovery compared to standard-of-care alone. Prospective multicenter studies are needed to confirm these findings.