High incidence of arterial thrombosis in young patients treated for multiple myeloma: results of a prospective cohort study.

This prospective study evaluated the risk of arterial thrombosis in 195 consecutive patients aged 18 to 65 years with newly diagnosed multiple myeloma (MM). All patients were treated with 3 cycles of VAD (vincristine, doxorubicin, and dexamethasone) or TAD (thalidomide-AD) or PAD (bortezomib-AD) in national trials, followed by high-dose melphalan and autologous stem cell transplantation. For a period of 522 patient-years, 11 of the 195 patients (5.6%) developed arterial thrombosis. The highest incidence was seen during induction chemotherapy courses. Median age at onset of arterial thrombosis was 59 years (range, 43-65 years). Hypertension and smoking were significantly associated with arterial thrombosis with a relative risk of 11.7 (2.23-61.2) and 15.2 (1.78-130), respectively. Factor VIII levels (FVIII:C) correlated significantly with age (P = .02) and higher International Scoring System (ISS) stage (P = .001). A higher FVIII:C was associated with arterial thrombosis (hazard ratio [HR] = 1.85; 95% confidence interval [CI] = 0.99-3.47) after adjustment for age, ISS score, and assigned treatment arm. MM patients have an increased risk for arterial thrombotic events during and after induction chemotherapy. Hypertension, smoking, and high factor VIII levels, possibly reflecting disease activity, contribute to the risk of arterial thrombosis.