Venous thromboembolism related to warm autoimmune hemolytic anemia: A case–control study

Autoimmune Hemolytic Anemia Confers an Independent Risk Factor for Thrombosis: Retrospective Cohort Study Using the “STRIDE” Database

“…Prior studies have shown that thrombosis is correlated with low hemoglobin at the time of AIHA onset and laboratory evidence of haemolysis [19,20]. We did not find these to be the case for our AIHA cohort.…”

“…Our results confirm that AIHA patients have a higher incidence of thrombosis (29%) than non-AIHA patients (19%). This thrombosis incidence in AIHA patients is on the higher end of present estimates that include 11% [19], 20% [20], and 27% [29]. This may be due to the enrichment for more medically complex patients at Stanford Hospital and Clinics.…”

“…Prior studies have been smaller in size or descriptive [5,26,27], done in the context of specific hyper coagulable states [28,29], or with a design that excluded secondary AIHA patients or lacked anon-AIHA cohort matched for relevant AIHA risk factors [14][15][16][17]19,20].…”

“…It has previously been showed that AIHA patients exhibited lower hgb levels at the time of their thrombotic event, suggesting that periods of severe haemolysis-or "hemolytic flares"-may be a risk factor for thrombosis [20]. We assessed this further by devising two metrics, "hemolytic flares" and total "hemolytic burden" (see Methods section for details).…”

“…Haemolysis is generally thought to cause thromboembolism due to the abnormal exposure of phosphatidylserine following red cell destruction, which promotes coagulation [18]. In support, work by Barcellini, et al [11] and Lecouffe-Desprets, et al have suggested that thrombosis in AIHA is associated with more severe anemia at the time of AIHA onset and at the time of the thrombotic event [19,20]. However, these studies excluded patients with secondary causes of AIHAi.e., lymphoproliferative disorders, infections, and autoimmune disorders-which comprise the majority of AIHA cases as mentioned above.…”