Risk of thromboembolic events associated with different multiple myeloma regimens in Taiwan: a nested case-control study

Although novel agents for multiple myeloma (MM) have a better response rate and survival in both newly diagnosed and relapsed/refractory MM patients, concerns regarding the association between MM treatments and thromboembolic events have been raised. The aim of this population-based study was to examine the association between different combinations of MM treatments and the risk of thromboembolic events. We conducted a nested case-control study using the Taiwan Cancer Registry (TCR) and National Health Insurance Research Database (NHIRD). Adult patients newly diagnosed with MM and treated with at least one of the immunomodulatory agents between 2008 and 2016 were identified. Among them, we further identified patients who developed thromboembolic events as cases and selected controls matched by age, sex and duration of MM diagnosis at a ratio of 1:5. The index date was defined as the day one year before the diagnosis date of thromboembolic events in the case group and the corresponding date in the control group. Conditional logistic regression was used to examine the association between different MM treatment regimens and the risk of thromboembolic events. A total of 4,180 newly diagnosed MM patients treated with at least one of the immunomodulatory agents were identified (mean age: 67.2 years; male: 55.7%). In this MM cohort, we further identified 388 cases and 1,940 matched controls (mean age: 71 years; male: 64.2%). The use of a thalidomide/bortezomib/steroid combination (odds ratio (OR) 2.95 [95% confidence interval (CI) 1.47–5.95]), thalidomide monotherapy (OR 3.33; 95% CI, 1.59–6.94), and a thalidomide/steroid combination (OR 4.24; 95% CI, 2.00-8.98) were associated with an increased risk of thromboembolic events. Other risk factors, particularly a history of thromboembolic events, including ischemic heart disease and pulmonary embolism, were significantly associated with increased risk of thromboembolic events. We found that the use of thalidomide alone and in specific combinations was associated with an increased risk of thromboembolic events.