Bleeding and thrombotic events in patients with heparin-induced thrombocytopenia: a two-decade single-center experience in Thailand.

INTRODUCTION: Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder with potential bleeding complications, yet data from Asian populations are scarce. OBJECTIVES: Our study aims to determine bleeding and thrombotic incidence and identify associated factors in Thai HIT patients. METHODS: We retrospectively and prospectively studied patients with suspected or confirmed HIT at Siriraj Hospital (January 2004‒December 2024). Fondaparinux was the sole non-heparin anticoagulant. Suspected HIT required a positive immunoassay or platelet aggregation test. RESULTS: Forty-one patients (mean age, 66.8 years) were included, of whom 33 had confirmed HIT. Five had thrombosis, 16 (39%) required intensive-care-unit admission, and 29 (70.7%) had renal impairment. Among these 29, 13 developed new-onset acute kidney injury, and 16 had pre-existing renal disease (14 progressed to acute kidney injury). Most received fondaparinux (n = 25), whereas 5 received regional citrate, 1 warfarin, and 10 no anticoagulation. Overall mortality was 29.3%. One non-anticoagulated patient developed pulmonary embolism. Bleeding incidence was 1.22% per day, affecting 11 patients (26.8%), of whom 10 had renal impairment and 7 met International Society on Thrombosis and Haemostasis criteria for major bleeding. Bleeding rates did not differ between confirmed and suspected HIT (24.2% vs. 37.5%; P = .658). Pre-existing chronic kidney disease (hazard ratio, 2.78; 95% CI, 0.84‒9.26; P = .095) and sustained low-efficiency dialysis (hazard ratio, 4.60; 95% CI, 1.50‒14.09; P = .008) were associated with bleeding. CONCLUSIONS: In this Thai cohort, HIT conferred a high bleeding risk, especially in patients with renal impairment. These findings underscore the need for renal-safe non-heparin anticoagulants in resource-limited settings. TRIAL REGISTRATION: TCTR20241227001.