Incidence Rate Of Venous Thromboembolism (VTE) and Utilization Of a VTE Prophylaxis Order Set Module In Hospitalized Patients With Leukemia
Authors: Kroll Michael H. , Ferrajoli Alessandra , Cheng Lee , Watkins Jack L. , Rodriguez Maria Alma 
Published: October 2019

Abstract

Introduction
The incidence of VTE in patients with leukemia is not known and the benefit of VTE prophylaxis in patients with leukemia has not been studied. For all hospitalized cancer patients the reported incidence of VTE has ranged from 0.6% to 18%. National guidelines and regulatory standards dictate that all patients be assessed for their risk of VTE and be treated accordingly. Beginning in August of 2011 our institution developed a VTE prophylaxis module that was integrated into hospital admission order sets. This module was aimed at standardizing the documentation of VTE risk assessment and ordering of VTE prophylaxis across all hospitalized patients, including patients with leukemia. We conducted this analysis to describe the utilization of the VTE prophylaxis order set module and the incidence rate of VTE events in hospitalized patients with leukemia.

Methods
We conducted a retrospective study of patients who were diagnosed with leukemia and were hospitalized at The University of Texas MD Anderson Cancer Center between January 1, 2012 and December 31, 2012 (1 year). All patients with hospital length of stay more than or equal to 3 days were included. The following information was collected for each Patient: type of leukemia, age, gender, VTE prophylaxis, and medication used for prophylaxis (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)). Use of mechanical prophylaxis (graduated sequential compression devices, and compression stockings) and contraindications to pharmacologic prophylaxis were collected for patients in which the order set module was used. Diagnoses of deep vein thrombosis (DVT) and/or pulmonary embolism (PE) were objectively confirmed by venous Doppler ultrasound, computed tomography (CT) or ventilation perfusion (VQ) scan. The unit of analysis was hospitalizations. No statistical comparisons were made.

Results
Over the 1 year 2686 hospitalizations occurred among 905 patients. Females comprised 40% of patients, 37% were aged 65 years or older, 66% of the patients were white, with African-American representing 11% and Hispanics 16%. The distribution of leukemia diagnosis among patients was acute myeloid leukemia (AML) 52.2%, acute lymphocytic leukemia (ALL) 22.4%, chronic lymphocytic leukemia (CLL) 12.9%, chronic myeloid leukemia (CML) 6.5%, chronic myelomonocytic leukemia (CMML) 3.4% and other leukemias 2.4%. There were 103 VTE events among the 2686 hospitalizations for an overall incidence rate of 3.8%. DVT was the most common event (3.2%), while PE alone (0.9%) or DVT+ PE (0.2%) were rare. VTE events by leukemia type were AML 4.3%, ALL 2.8%, CLL 5.1%, CML 3.8%, CMML 3.9% and other leukemias 0.0%. The VTE prophylaxis order set module was utilized in 92.2% of admissions and from those mechanical prophylaxis was the most commonly ordered intervention, 1496 (55.7%), followed by no prophylactic intervention, 931 (34.6%), and 49 (1.8%) with both mechanical and pharmacologic prophylaxis. The VTE incidence by prophylaxis type was 4.0% for mechanical prophylaxis, 3.8% for no prophylaxis, and 6.1% for both mechanical and pharmacologic prophylaxis. There were 210 (7.8%) admissions in which the VTE prophylaxis module was not utilized and the incidence of VTE was 2.4%. Of these admissions 40 (19.0 %) were prescribed pharmacologic prophylaxis based on pharmacy dispensing records.

Conclusion
This observational study demonstrates that the overall incidence of VTE in hospitalized patients with leukemia is 4% overall, and occurs in both acute and chronic leukemias. The most common event is DVT alone, and PE events (with or without DVT) are very rare. Hence, the role of pharmacologic or other interventions in preventing DVT in leukemia patients is not clear. Future studies should prospectively evaluate risk factors that predict DVT, as well as measure the effectiveness of current strategies for VTE prophylaxis in patients with leukemia.

Disclosures:
Kroll: Aplagon Therapeutics: Membership on an entity’s Board of Directors or advisory committees. Rodriguez:Pfizer: Research Funding; Glaxo-smith Kline: Research Funding; Amgen: Research Funding; Ortho-Biotech: Research Funding.