Venous Thromboembolism in Hematopoietic Stem Cell Transplantation

Background:

Venous thromboembolism (VTE) is an underappreciated complication seen amongst allogeneic and autologous hematopoietic stem cell transplant (HSCT) patients and a major cause of morbidity and mortality. Despite these challenges, VTE in HSCT remains understudied, with a paucity of established guidelines on thrombosis surveillance, prevention, and treatment. Balancing risk of bleeding and thrombosis is particularly challenging as HSCT patients are concurrently pancytopenic and coagulopathic. We aimed to describe the incidence, predictors, and adverse events of VTE amongst patients at 90 days post-HSCT.

Methods:

We conducted a retrospective cohort study of adult patients, age >18-years-old, who underwent HSCT for a hematological malignancy between January 1, 2011 and December 31, 2021 at a tertiary care centre in Canada. Patients were followed from transplant until Day 90 post-transplant, or death. Baseline, transplant, laboratory, and cancer characteristics were analyzed.

Results:

Four Hundred and Seventy Six (476) HSCT patients were included (age range 18 – 74), 285 (59.9%) of our patients were male, and 191 (40.1%) were female. Three Hundred and Seventeen (317) (66.6%) patients underwent autologous transplant, and 159 (33.4%) patients underwent allogeneic transplant (Table 1). Forty Seven (47) patients (9.8%) suffered from VTE within 90 days post-HSCT; 74.5% were catheter related. 9.43% of allogeneic, versus 10.09% autologous patients were diagnosed with VTE (p=0.820). 11.9% of allogeneic, versus 4.1% of autologous patients (p=0.001) suffered from bleed unrelated to anticoagulation. There was significant association of VTE post-HSCT with history of unprovoked DVT (p = 0.026), previous treatment with steroids (p = 0.032), infectious complications (including bacteremia (p = 0.025), and skin and soft tissue infection (p < 0.001)), use of peripherally-inserted central catheters (PICCs (p <0.001), left-sided CVC placement (p = 0.007), second central venous line insertion (due to complications from the first) (p < 0.001), and blocked or malfunctioning central venous catheter (p = 0.003). There was no significant association of VTE post-HSCT with transplant graft (autologous versus allogeneic), underlying hematological malignancy, age, BMI, or sex. Mortality rate at 90 days amongst VTE patients was 14.89%, versus 3.27% in non-VTE patients (p < 0.001) (Figure 1).

Conclusion:

The majority of VTE post-HSCT were catheter-related and were more frequently associated with use of PICCs. VTE post-HSCT was associated with higher mortality. VTE prophylaxis or active surveillance could be considered in patients with the above-mentioned risk factors balancing the risk of bleeding, particularly in allogeneic stem cell transplant patients, and those who are concurrently thrombocytopenic.