Venous Thromboembolism in Hospitalized Patients with Multiple Myeloma: A Nationwide Analysis
Authors: Mohammed Kahee A , Sanfilippo Kristen M 
Published: October 2019

Abstract
Background: The burden of multiple myeloma has increased in last 30 years, both in US and globally. Patients with multiple myeloma are at increased risk of developing venous thromboembolism (VTE) resulting in significant morbidity and mortality. This study aimed to (1) determine patient and hospital characteristics associated with VTE, (2) assess the impact of VTE on in-hospital mortality and prolonged hospitalization, and (3) examine trends in the rates of VTE and VTE-associated in-hospital mortality and prolonged hospitalization in patients with multiple myeloma.
Methods: A retrospective analysis of Nationwide Inpatient Sample, 2008 - 2014, was conducted. International Classification of Diseases-9-Clinical Modification codes were used to identify hospitalized patients (aged ≥ 18 years) with multiple myeloma. Trends in the prevalence of VTE and VTE-associated in-hospital mortality and prolonged hospitalization rates were assessed using the Cochrane-Armitage test. Weighted, multilevel hierarchical logistic regression using generalized linear mixed models with generalized estimated equations were used to examine the association between patient and hospital characteristics and study outcomes
Results: Among 136,652 hospitalized patients with multiple myeloma, 4.2% were diagnosed with VTE. Although statistically insignificant, a slight increase in VTE rates were observed from 2008 to 2014 (3.9% to 4.4%) (p 0.18). In adjusted multilevel hierarchical regression, we found higher odds of VTE in male gender (odds ratio [OR] = 1.08, 95% Confidence Interval [CI] = 1.02 - 1.14), Black race (OR = 1.11, 95% CI = 1.03 - 1.19), those who had a major surgery (OR = 1.73, 95% CI = 1.62 - 1.85), and higher Elixhauser comorbidity index (OR = 3.73, 95% CI = 2.66 - 5.23). Hospital level correlates of VTE included: admission to teaching vs. non-teaching (OR = 1.07, 95% CI = 1.01 - 1.13), and admission to medium vs. small sized hospitals (OR = 1.11, 95% CI = 1.01 - 1.23), while lower odds of VTE were noted among patients admitted to hospitals located in Northeast (OR = 0.91, 95% CI = 0.84 - 0.98) vs. South. Patients diagnosed with vs. without VTE had higher odds of in-hospital mortality (OR = 1.36, 95% CI = 1.22 - 1.51) and prolonged hospital stay (OR = 1.65, 95% CI = 1.55 - 1.75). A statistically significant trend for decreasing VTE associated mortality (10.0% to 5.3%) (p <.001) and prolonged hospitalization (32.1% to 28.2%) (p <.001) rates were observed across study years.
Conclusions: During the study period, there has been an increase in rate of VTE among patients with multiple myeloma. Patients with multiple myeloma and VTE had a high risk of in-hospital mortality compared to those without VTE; however, rates of VTE-associated in-hospital mortality and prolongation of hospitalization have decreased over time. Hospital level characteristics were significantly associated with VTE. These findings might reflect changing detection guidelines and better management of VTE in cancer patients. Lastly, patient level characteristics independently predict the occurrence of VTE. Given the higher in-hospital mortality associated with patients with VTE and multiple myeloma, there is a need for prospective studies to identify effective strategies to prevent VTE in this patient population and improve outcomes.

Disclosures
Sanfilippo: Bristol-Myers Squibb: Speakers Bureau.