Family History of Venous Thromboembolism As a Risk Factor for Thrombosis in Multiple Myeloma Patients: A Population-Based Study,

Patients with multiple myeloma are at an increased risk of venous thromboembolism (VTE), especially when treated with thalidomide and lenalidomide. The etiology of this is largely unknown, but probably involves both genetic and environmental factors. Family history of VTE is a known risk factor for VTE in the general population, including known inherited thrombophilic abnormalities. The influence of a family history of VTE as a potential risk factor for VTE in multiple myeloma patients is unknown. To expand our knowledge on this topic, we conducted a large population-based study based on all multiple myeloma patients diagnosed in Sweden 1958–2004.

We assessed the impact of family history of VTE as a risk factor for VTE among 21,067 multiple myeloma patients and 83,094 matched controls. Data on multiple myeloma patients was gathered from the Swedish Cancer Registry, information on first-degree relatives from the national Multigenerational Registry, and occurrence of VTE from the nationwide Patient Registry. We calculated odds ratios (OR) and 95% confidence intervals (CI) using chi-square.

Of the 21,067 multiple myeloma patients included in the study (54% males, median age at diagnosis 71 years), 66% had an identifiable first-degree relative. VTE was diagnosed in 1,429 multiple myeloma patients, and 921 had a family history of VTE. Compared to multiple myeloma patients without a family history of VTE, multiple myeloma patients with a family history of VTE had a 2.2-fold (95% CI 1.8–2.7; p<0.001) higher risk of VTE. Among 4,986 controls that were diagnosed with VTE, 316 had a family history of VTE. Controls with a family history of VTE had a 1.5-fold (95% CI 1.3–1.7; p<0.001) increased risk of VTE compared to controls without a family history of VTE. The difference of the impact of family history of VTE on the risk of VTE in multiple myeloma patients versus controls was significant.

In this large population-based study including more than 20,000 multiple myeloma patients, we found family history of VTE to have a larger impact on VTE risk in multiple myeloma than in matched controls. Our findings confirm that genetic factors contribute to thrombophilia in multiple myeloma and may have therapeutic implications regarding thromboprophylaxis and treatment.

No relevant conflicts of interest to declare.