Incidence and Risk Factors of Early Onset VOD/SOS Differ in Younger vs Older Adults After Stem Cell Transplantation.

Veno-occlusive disease (VOD) is a rare but potentially life-threatening complication following allogeneic hematopoietic stem cell transplantation (allo-SCT). While increasing awareness and modern transplant techniques have mitigated risk, the interaction of historic risk factors in the current era with post-transplant cyclophosphamide (PTCy) is unknown. We performed a retrospective single center analysis of adult patients 18 years or older undergoing allo-SCT (N=1561) using predominately PTCy as GVHD prophylaxis (72%). We found a higher rate of VOD at 16.8% (20/119) in those aged ≤ 25 years compared to 3.8% (55/1442) in those >25 years, with unique predictors of VOD within each cohort. Multivariate classification and regression tree (CART) analysis confirmed age as the primary independent determinant of the rate of VOD. Within patients aged 18-25 years, disease risk index (DRI) (31% with high/very high DRI vs 12% low/intermediate DRI; p=0.03) and prior lines of chemotherapy (24% with >1 vs 6% with ≤1, p=0.03) were the strongest predictors of VOD. Incidence of VOD in patients > 25 years of age consistently ranged between 3-5% across most risk factors evaluated, with only hepatic factors (baseline elevation of bilirubin, aspartate transferase (AST), alanine aminotransferase (ALT)) or gemtuzumab exposure associated with increased rates of VOD. There was no significant difference in rates of VOD in those receiving PTCy compared to those receiving alternate GVHD prophylaxis. Our data highlight the differences in incidence and predictors in VOD between younger (≤25) and older (>25) adults undergoing allo-SCT.