Venous Thromboembolism in Individuals with Sickle Cell Disease- a Retrospective Review of This Understudied Problem

Individuals with sickle cell disease (SCD) are proposed to be at a higher risk for venous thromboembolism (VTE) compared to the general population. Observational studies show a 25% increased risk of first VTE in SCD with a mean age of incidence of 30 years, which is much lower than the general population of 65 years. The mechanisms for this increased VTE risk have been proposed to be increased hemolysis causing increased venous stasis and vasculopathy, increased endothelial activation with increased activation of the coagulation pathway and chronic inflammation.

In this study, we reviewed the medical records of 783 individuals with SCD who were followed in our lifelong sickle cell center between May 2013 to May 2023 to determine the prevalence of thrombosis and associations of these events with laboratory and clinical risk factors of thrombosis. We collected retrospective data including patient demographics, clinical history, and laboratory data at the time of VTE events and an evaluation of the presence of a central venous catheter (CVC) in our population. VTE was defined as occurrence of deep vein thrombosis (DVT), pulmonary embolism (PE), cerebral sinus venous thrombosis (CSVT), or right atrial thrombosis.

The prevalence of VTE in our population was 8.2% (n = 64 out of 783), with a median age of 33 years. Out of 64 total patients who developed a VTE during our study period, 21 developed a PE; this was 33% of the VTE events noted. A high body mass index (BMI) (>30 kg/m2) was noted among 22% of the patients in the VTE group compared to 7.6% of the non-VTE group (p<0.001). Smoking was noted in 41% of the VTE group patients compared to 10% in the control group (p<0.001). CVCs were present in 55.6% of the patients in the VTE group compared to those in the non-VTE group (10%) with a p <0.001. Twenty-two patients (34.4%) of the patients in the VTE group had a history of a VTE event prior to our study period and were having a recurrent VTE episode during our study period between 2013 and 2023. In addition, out of those patients who developed a VTE during our study period, 20 patients (31%) developed a recurrent VTE event during our study period.

Our results show that there is a higher rate of obesity and smoke exposure among patients with SCD who develop a VTE event. PE's are a substantial number of VTE events in the SCD population. We also noted a significant correlation between CVCs and VTEs in SCD. There is high recurrence rate of VTEs among SCD patients. Based on these findings, future prospective data are needed to determine if these associations are clear risk factors for VTE in SCD so these risk factors can be minimized in patients at risk for VTE events.

Bhasin:Global Blood Therapeutics: Research Funding; Forma Therapeutics: Research Funding; Pfizer: Research Funding; Novartis: Honoraria.