Trends in Venous Thromboembolism Events in Hospitalized Acute Lymphoblastic Leukemia Patients - National Inpatient Database Study

Background Studies show that venous thromboembolism (VTE) increases mortality in adult cancer patients and children with acute lymphoblastic leukemia (ALL), however less data is available for adults with ALL. This study aims to find the prevalence and outcomes of VTE in adult ALL patients with and without remission and relapsed cases. Methods This is a retrospective cohort study involving adult hospitalized ALL patients across the United States included in the National Inpatient Database (NIS) 2016-2020. Statistical analysis was performed using STATA BE software and ICD 10 diagnostic codes. Continuous data is presented as means and categorical data is presented as percentages. Logistic regression was used to analyze the association between ALL (with/without remission and relapsed), VTE, and in-hospital mortality while adjusting for age, gender, race, bone marrow transplantation status (BMT), chemotherapy, thrombophilia, obesity, diabetes, hypertension, heart failure, kidney disease, dyslipidemia, smoking status, and alcohol intake. Results Among 139,778 ALL patients, 107,629 (77.00%) had ALL without remission (ALLw/oR), 23,651 (16.92%) had ALL with remission (ALLwR), and 8,918 (6.38%) had relapsed ALL (rALL). ALLw/oR [61.95 士 26.06 years, 50.52% females] had the highest mean age and female population, followed by ALLwR [40.69 士 30.30 years, 41.91% females] and rALL [40.60 士 25.54 years, 38.70% females]. Current or past VTE was reported in 10,978 (10.20%) ALLw/oR patients, 2339 (9.89%) ALLwR patients, and 1150 (12.90%) rALL patients during hospitalization. In-hospital deaths were reported in 4703 (4.37%) ALLw/oR, 478 (2.02%) ALLwR, and 561 (6.29%) rALL patients. rALL was significantly associated with VTE [OR 1.46, 95%CI 1.08-1.98] while ALLw/oR [OR 1.06, 95%CI 0.78-1.43] and ALLwR [OR 1.17, 95%CI 0.86-1.58] were not. BMT [OR 1.77 95%CI 1.62-1.93] and chemotherapy [OR 1.18, 95%CI 1.13-1.23] showed a significant association with VTE. VTE was associated with increased in-hospital mortality [OR 1.14, 95%CI 1.05-1.24] in ALL patients with the strongest association observed in rALL patients [OR 2.06, 95% CI 1.19-3.54]. Interestingly, ALLw/oR [OR 0.82, 95%CI 0.47-1.41] and ALLwR [OR 0.59, 95%CI 0.34-1.01] were associated with lower mortality in those with VTE, although statistically insignificant. While BMT [OR 1.43, 95%CI 1.23-1.67] was associated with significantly higher mortality while chemotherapy was associated with lower mortality [OR 0.48, 95%CI 0.43-0.53]. Conclusion VTE prevalence and in-hospital mortality were the highest in rALL patients, which comprised of younger patients and fewer females as compared to ALLw/oR and ALLwR. BMT correlated with higher VTE rates and deaths while chemotherapy, despite its prothrombotic potential, was associated with less VTEs and deaths. Prospective studies are needed to evaluate VTE incidence and outcomes in ALL patients, while also taking bleeding risks into account, to assess the need for VTE prophylaxis in these patients.