Long-term outcome of sinusoidal obstruction syndrome secondary to hematopoietic stem cell transplantation.

BACKGROUND & AIMS: Sinusoidal obstruction syndrome (SOS) is a potentially severe complication of conditioning regimens in hematopoietic stem cell transplantation (HSCT). Its long-term outcome is unknown. The aim of this study was to investigate the long-term liver outcome of patients with SOS. METHODS: We retrospectively analyzed the outcome of all patients with histologically proven SOS related to HSCT conditioning who survived 6 months or more after HSCT. 22 patients with SOS were included. RESULTS: Median follow-up after SOS was 6.1 years. During this period, 10 patients (45%) developed signs of portal hypertension and 8 (36%) of them liver-related complications (ascites, n=8; spontaneous bacterial peritonitis, n=1; hepatic encephalopathy, n=3; variceal bleeding, n=3). Cumulative incidence of signs of portal hypertension was 27% at 3 years. Patients who developed signs of portal hypertension were less likely to have received defibrotide (hazard ratio:0.096; p<0.001) and had lower mean arterial pressure than those who did not. Of the 10 patients who developed signs of portal hypertension during follow-up, 3 underwent a second liver biopsy; all biopsies showed features of porto-sinusoidal vascular disorder. Cumulative incidence of death, considering non-liver-related death as a competing event, was significantly higher in patients who developed signs of portal hypertension than in those who did not [hazard ratio: 10.7 (1.27-89.9)]. CONCLUSION: Development of signs of portal hypertension and liver-related complications are common in the long-term after SOS following HSCT, especially when patients did not receive defibrotide, and this affects patients' survival. Features consistent with a porto-sinusoidal vascular disorder may be seen in liver histology in a subset of patients at the long-term follow-up after SOS. IMPACT AND IMPLICATIONS: Long-term liver outcome of sinusoidal obstruction syndrome (SOS) following conditioning regimens in haematopoietic stem cell transplantation (HSCT) is unknown.This study demonstrates that signs of portal hypertension and liver-related complications are common during long-term follow-up after SOS following HSCT. Treatment of SOS with defibrotide seems to be associated with a lower risk of developing portal hypertension. Liver histology at the long-term follow-up after SOS may show features consistent with PSVD.SOS following HSCT might thus be removed from the PSVD exclusion criteria.