ST. LOUIS, MO — While guidelines for multiple myeloma advise pharmacologic prophylaxis to prevent development of venous thromboembolism (VTE) in high-risk patients, current risk assessment tools differ in the factors considered indicative of high risk and in the patients determined to need preventive anticoagulation.
A study presented today at the 2018 American Society of Clinical Oncology Annual Meeting in Chicago addresses the need for a reliable, validated risk prediction model for VTE in multiple myeloma patients.1
Researchers led by Kristen Marie Sanfilippo, MD, MPHS, of the John Cochran VAMC in St. Louis, MO, identified 3,036 patients who received chemotherapy for multiple myeloma between September 1999 and December 2013 through the Veterans Administration. Of those, 371 developed VTE during the first six months of chemotherapy for the disease.
The researchers evaluated variables associated with increased risk of VTE within six months of chemotherapy initiation in a univariate analysis as well as those variables previously identified in the literature to develop and then validate a Myeloma Clot Score. The score can be used to predict which patients would most benefit from thromboprophylaxis, while minimizing exposure to anticoagulants in patients for whom they would provide little or no benefit.
Two factors nearly tripled the risk of VTE in multiple myeloma patients receiving chemotherapy—previous VTE and receipt of high-dose dexamethasone. The team assigned four points for each. Low-dose dexamethasone received three points based on a doubling of risk. Two factors increased the risk between 1.5 and two times—receipt of thalidomide and presence of a central venous catheter. Each of those received three points in the calculation. Erythropoietin, BMI of 25 and diagnosis before 2008 each received a point, while Asian patients had a reduction of three points and those on warfarin had scores reduced by six points.
In the validation cohort, patients who had a score of nine or higher had a nearly 60% risk of VTE, while the rate dropped by more than half, to 25%, in those with scores between six and eight. Patients with a Myeloma Clot Score of two to five had an 11% risk and those with one point or less had a risk of just 4.4%.
1Sanfilippo KM, Wang T-F, Luo S, et al. Prediction of venous thromboembolism in multiple myeloma: Myeloma clot score. J Clin Oncol 36, 2018 (suppl; abstr 6585).