GVHD severity, donor-recipient blood type impact thromboembolic event risk

In patients who develop chronic graft-versus-host disease (cGVHD) after haematopoietic cell transplantation (HCT), the risk of thromboembolic events (TEE) seems to be affected by disease severity and donor-recipient ABO blood group, a recent study has found.

Researchers enrolled 145 adults (median age 52 years, 66 percent men) who had received matched-sibling or umbilical cord blood donor HCT and developed cGVHD afterward. TEE was defined to include venous thromboembolism and pulmonary embolism events, as confirmed by imaging tests and requiring treatment.

Thirty-two participants (22 percent) developed at least one TEE, while 14 (10 percent) had two such events. Deep vein thrombosis was the most common TEE both for the first (81 percent) and second (86 percent) episodes. Over the 5-year observation period after cGVHD diagnosis, the cumulative incidence of TEE was 22 percent.

Severity of cGVHD seemed to be an important risk factor for TEE, with 5-year cumulative incidence rates of 9 percent, 17 percent, and 38 percent in patients with mild, moderate, and severe disease, respectively. The same was true for donor-recipient ABO blood group: those with O-O blood types saw a lower TEE cumulative incidence compared to all other ABO pairings.

Multivariate regression analysis confirmed these findings, showing that worse cGVHD severity increased TEE risk (hazard ratio [HR], 4.9, 95 percent confidence interval [CI], 1.1–22.0; p=0.03), as did non-O donor-recipient blood type matches (vs O-O donor-recipient pairs: HR, 2.7, 95 percent CI, 1.0–7.5; p=0.053).

Notably, TEE did not seem to significantly affect 2-year nonrelapse and 5-year overall survival.