Incidence, determinants and the transient impact of cancer treatments on venous thromboembolism risk among lymphoma patients in Denmark

BACKGROUND: Valid estimation of the incidence and risk factors for venous thromboembolism (VTE) among lymphoma patients has been limited by small studies focused on selected lymphoma subtypes and failure to account for death as a competing risk. Using a nationwide cohort of Danish lymphoma patients diagnosed from 2000 to 2010, we examined the incidence and risk factors for VTE and evaluated the transient impact of cancer treatments on VTE risk. METHODS: Medical databases contained cancer, comorbidity, treatment, and VTE information. We computed VTE incidence rates (IRs) per 1000 person-years and 1- and 2-year incidence accounting for competing risks. Using Cox proportional hazards models, we identified factors associated with VTE risk. In a nested self-controlled design, we evaluated the transient effect of chemotherapy, radiation, central venous catheter use and rituximab on VTE risk using logistic regression models and adjusted odds ratios (aORs). RESULTS: VTE IRs were >40/1000 person-years within 180 days post-diagnosis, decreasing to 8/1000 person-years in year two. VTE risk was 2.9% and 3.5% at 1 and 2 years, respectively. Lymphoma subtype, central nervous system involvement, and elevated lactate dehydrogenase were associated with VTE risk. Central venous catheter use increased the transient odds of VTE (aOR=6.7 (1.2, 28.1)). CONCLUSIONS: We report a lower VTE incidence among lymphoma patients compared with prior studies. Lymphoma aggressiveness was the main driver of baseline VTE risk, whereas central venous catheter use increased transient risks. These accurate estimates may improve the identification of lymphoma subgroups at highest VTE risk, for whom future targeted prevention interventions may be beneficial.