From the Guidelines
The prevalence of Sinusoidal Obstruction Syndrome (SOS) is approximately 14% in hematopoietic stem cell transplantation (HSCT) patients, as reported in the most recent and highest quality study available 1. The incidence of SOS has declined over the years due to the development of prophylactic therapy, avoidance of certain drug regimens, and lower doses of total body irradiation in HSCT. Key factors that influence the prevalence of SOS include:
- Patient risk factors
- Type of drug regimen
- Number of cycles of chemotherapy
- Diversity in clinical or histological diagnostic criteria Some of the key statistics on SOS prevalence include:
- 14% in HSCT patients, as mentioned earlier
- A decline from 50% in previous years, indicating significant progress in prevention and management 1 It is essential to recognize SOS early, as severe cases can have a high mortality rate if left untreated. Prophylaxis with certain medications has been shown to reduce the incidence of SOS in high-risk patients. The diagnosis of SOS is based on clinical criteria, including hyperbilirubinemia, painful hepatomegaly, ascites, and unexplained weight gain occurring within a specific timeframe after the causative treatment.
From the Research
Prevalence of Sinusoidal Obstruction Syndrome (SOS)
- The prevalence of SOS, also known as hepatic veno-occlusive disease (VOD), varies among different studies.
- According to a study published in the Clinical Journal of Oncology Nursing 2, SOS/VOD affects about 1 in 7 patients undergoing hematopoietic stem cell transplantation (HSCT).
- A retrospective multicenter study published in the Biology of Blood and Marrow Transplantation journal 3 found that the incidence of SOS/VOD in children was 2% among 5072 transplants considered at risk.
- Another study published in the British Journal of Haematology 4 mentions that SOS has a relatively low incidence, but cases that evolve to multi-organ failure have a high mortality rate.
- A review published in the Transfusion and Apheresis Science journal 5 states that hepatic VOD/SOS is a rare, possibly life-threatening complication of HSCT, but does not provide a specific prevalence rate.
- An older study published in the International Journal of Hematology 6 discusses the decision-making process for orthotopic liver transplantation in patients with severe SOS, but does not provide information on the prevalence of the condition.
Risk Factors and Incidence
- The study published in the Biology of Blood and Marrow Transplantation journal 3 identified risk factors associated with the development of SOS/VOD, including age < 2 years, use of busulfan during the conditioning regimen, female gender, and hemophagocytic lymphohistiocytosis.
- The same study found that the median time of SOS/VOD occurrence was 17 days after HSCT, and the overall mortality directly related to SOS/VOD was 15.5%.
- The review published in the Transfusion and Apheresis Science journal 5 mentions that risk stratification is essential, but conflicting results have been shown in studies aiming to define risk factors for development of VOD/SOS.