The Risk Factor Assessment Score and Incidence of Venous Thromboembolism In 629 Patients Undergoing Hematopoietic Stem Cell Transplantation Implications for VTE Prophylaxis

Individuals with hematologic malignancies, are at high risk for Venous thromboembolism (VTE). In patients undergoing hematopoietic stem cell transplantation (HSCT) the incidence and risk of VTE is unclear. Based on this it is difficult to consider prophylaxis in patients who are at potentially high risk for bleeding complications (Gerber, Blood 2008). It is increasingly becoming important to measure the risks of VTE, as the incidence has continued to rise. Different scoring systems have been proposed to assess the risks of VTE in hospitalized patients. In patients who develop VTE during hospitalization their risk of morbidity and mortality is increased. We examined 286 patients who received autologous HSCT transplantation, and 343 patients who underwent allogenic HSCT transplantation at the University of Michigan. We then compared their scores based on the risk assessment score developed by Caprini et al (Ann. Of Surg. 2010). The scoring system was initially validated for patients undergoing surgical procedures, and is currently in use at the University of Michigan to asses risk in bone marrow transplant patients. Risks for the development of VTE range from 10–20% (for moderate risk), 20–40% (higher risk), and 40–80% (highest risk). Objectives: To evaluate the efficacy of Caprinis' risk factor assessment scoring system in patients undergoing autologous and allogenic HSCT and determining the incidence of VTE in the patient cohort.

The medical records of 629 patients between 2005–2008 who received high dose chemotherapy followed by autologous (287) and allogenic (343) stem cell transplants were reviewed. The autologous patient cohort had a mean age of 48.9, and an average BMI of 29.01. The allogenic patient cohort had a mean age of 42.5, with an average BMI of 27.53. HSCT was performed for all of the following conditions: Non-Hodgkin's lymphoma, Neuroblastoma, Multiple myeloma, Leukemia, Myelodysplastic Syndrome, and Hodgkin's lymphoma. The scores were compiled on the day of admission or at the closest date to the actual stem-cell transplant. Based on scoring, the actual incidence of non catheter related VTE in the HSCT patient population was observed. Allogenic patients were observed for VTE incidence from admission to day 30, day 30–100, and 100 days and on. Autologous patients were observed from admission to day 30. Results: 1) Of the 286 patients receiving autologous transplantation the average Caprini risk assessment score was 6.4. The 343 patients receiving allogenic transplantation had an average score of 5.95. Twenty-seven autologous, and fifty-three allogenic patients were at higher risk (3-4 point range) with a 20–40% chance of developing a VTE. 259 autologous patients, and 287 allogenic patients were at the highest risk (5+ point range) with a 40–80% chance of developing a VTE. 2) In both patient cohorts, based on the Caprini risk assessment score HSCT patients were placed in the highest risk category with a 40–80% chance of developing a VTE. 3) Only two patients (0.69%) developed an actual VTE during hospitalization for autologous HSCT. These patients both had a score of 10. Two patients (0.58%) receiving allogenic HSCT developed a VTE from the time of admission to 30 days. These patients had an average score of 7.5. From 30–100 days 5 patients deve loped a VTE, of these patients 1 developed CGVHD, The patients had an average score of 7.6. Twenty patients developed a VTE greater then 100 days, of these patients, 4 of which developed CGVHD. The patients had an average score of 6.55. Conclusion: The Caprini Venous Thromboembolism risk factor a ssessment score is not valid in patients undergoing high dose chemotherapy followed by an autologous or allogenic transplant. HSCT patients are at high risk for bleeding complications and the risk of VTE is relatively low (<1%). Only 2/286 (autologous transplant 0.69%) patients developed a VTE, and 2/343 (allogenic transplant) patients (0.58%) went on to develop a VTE. While VTE prophylaxis may be warranted in surgical and hospitalized patients, this study suggests it may not be necessary in patients undergoing HSCT who are at high risk of bleeding complication.

No relevant conflicts of interest to declare.