Incidence, risk factors, and outcomes of patients with monoclonal B-cell lymphocytosis and chronic lymphocytic leukemia who develop venous thromboembolism.

Background: The incidence, risk factors, and outcomes of venous thromboembolism (VTE) in patients with chronic lymphocytic leukemia (CLL) and monoclonal B-cell lymphocytosis (MBL) are not well described.

Objectives: We aimed to determine the clinical characteristics, risk factors, and outcomes of incident VTE in patients with newly diagnosed MBL/CLL and compare the incidence to the age- and sex-matched general population.

Methods: Using the Mayo Clinic CLL Database, we identified 946 patients with newly diagnosed MBL/CLL between 1998 and 2021. Incidence of VTE was identified by querying the electronic health record for VTE-specific International Classification of Diseases-9 and -10 codes and reviewing results of radiographic studies.

Results: Eighty patients developed VTE. The incidence of VTE in patients with newly diagnosed MBL/CLL was ∼1% per year. In multivariable analyses, prior history of VTE (hazard ratio [HR]: 5.33; 95% CI: 1.93-14.68, P = .001) and high/very high-risk CLL-International Prognostic Index score (HR: 2.63; 95% CI: 1.31-5.26; P = .006) were associated with an increased risk of VTE; receipt of CLL treatment or occurrence of nonhematologic malignancy was not. Development of VTE was associated with shorter overall survival (HR: 1.82, 95% CI: 1.30-2.55) after adjusting for age, sex, prior history of VTE, and Rai stage. The age- and sex-adjusted VTE incidence rate for patients with MBL/CLL and no prior history of VTE (n = 904) was 1254 per 100 000 person-years compared with 204 per 100 000 person-years in the general population, reflecting a 5.9-fold increase.

Conclusion: Our study demonstrates a 6-fold increased risk of VTE in patients with MBL/CLL compared with the age- and sex-matched general population.