Researchers explored the association between thrombotic events and autoimmune hemolytic anemia (AIHA), a common occurrence in patients with cold agglutinin disease (CAD). They found thromboses in these patients to be associated with intravascular hemolysis, multitreatment, the need for transfusions, and infections, as published in the Journal of Thrombosis and Haemostasis.

“Recent epidemiologic studies found a frequency of about 20% of venous and arterial thrombosis (including ischemic stroke) in CAD and [warm AIHA], significantly higher than in the general population,” the authors explained. “Thrombotic episodes occurred in 11% of AIHA patients, were mainly grade 3, and required hospitalization in the great majority of cases.”

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The research team conducted a retrospective analysis of 287 patients with AIHA at an Italian reference center over a median follow-up period of 51 months. In addition, they prospectively studied 174 patients from the same cohort who had an AIHA relapse between January 2020 and December 2021.

A total of 33 patients developed mainly venous thromboses and 70% of them were hospitalized. The authors determined that, in addition to the other aspects, therapy with rituximab and cyclophosphamide were risk factors for thromboses.

In the prospective follow-up, 45 of the patients 174 experienced 70 acute hemolytic episodes, including 16 new diagnoses and 29 relapses. No thrombotic complications developed in those patients on primary anticoagulant prophylaxis and 30% of the patients with active hemolysis (lactate dehydrogenase ≥1.5 x the upper limit of normal) developed thrombotic events. Therefore, the authors recommend primary prophylaxis in patients in these settings.


Fattizzo B, Bortolotti M, Giannotta JA, et al. Intravascular hemolysis and multitreatment predict thrombosis in patients with autoimmune hemolytic anemia. J Thromb Haemost. Published online May 12, 2022. doi:10.1111/jth.15757