Sickle Cell Disease and Venous Thromboembolism: Hospital Mortality, Length of Stay and Cost
Authors: Rainone Michael , Perimbeti Stuthi Pavani , Shrivastav Rishi , Glassberg Jeffrey A. , Cytryn Lawrence 
Published: October 2019

Abstract
Introduction:
It is estimated that there are 100,000 Americans living with Sickle Cell Disease (SCD). Patients with SCD experience a number of complications that frequently require hospitalization. SCD is a prothrombotic state that is commonly complicated by venous thromboembolism (VTE) and recurrent VTE. The National Heart, Lung and Blood Institute do not include VTE as one of the complications of SCD in their latest guidelines, and the topics of prophylaxis and treatment of VTE in SCD are not discussed. There are no guidelines specifically designed for the prophylaxis or treatment of VTE in the SCD population, and traditionally management guidelines for VTE in the general population are followed. Recent information on national prevalence, mortality, length of stay, and cost for hospitalized patients with with SCD complicated by VTE is limited.
Methods:
We used data from the Healthcare Cost and Utilization Project's National Inpatient Sample (NIS) from 1999-2014 to examine these variables. The data on SCD from 1999-2014 was analyzed using ICD-9-CM codes for SCD (ICD-9-CM: 282.41, 282.42, 282.6, 282.60, 282.62, 282.63, 282.64, 282.68, 282.69) in the primary diagnosis field, and VTE (ICD-9-CM: 453.40, 453.41, 453.42, 453.82, 453.83, 415.11, 415.19) in the secondary diagnosis field which includes codes for venous thrombosis and pulmonary embolism. Univariate and bivariate statistical analysis was performed using the chi-square test. Multivariate analysis was performed using cox proportional hazard regression. The alpha was set at 0.05.
Results:
Over a 15 year period, from 1999-2014, a total of 217,791 (weighted N = 1,073,215) admissions with SCD were identified. A total of 7,898 admissions were associated with VTE. Mean age at admission of those with VTE was 27.42 (+/- 0.05) years and those without VTE was 34.00 (+/- 0.51) years. In patients with SCD and VTE, the average inpatient mortality was 3.08% (p < 0.0001) versus mortality of 0.27% in patients that did not have VTE. The hazard ratio for mortality was 4.18 (CI: 2.95-5.93) (p < 0.0001). Length of stay in the SCD with VTE group was 10.45 days (+/- 0.43) versus 5.09 days (+/- 0.02) (p < 0.0001) in SCD without VTE. Overall hospital cost was higher in those with VTE at $60,055 (+/- $1,940) versus $28,729 (+/- 232.97) (p < 0.0001) in those without VTE.
Conclusions:
Patients with SCD and VTE experience significant morbidity, mortality, prolonged hospitalization and increased cost associated with this complication of the disease as was observed in this study. Furthermore, patients who experience VTE are significantly younger than those who do not, with mean age of 27 versus 34. After controlling for multiple confounders like age, race, sex, income, comorbidities, the presence of VTE is associated with a significantly higher risk of mortality in SCD. Currently, there are no prophylaxis or treatment guidelines designed specifically for patients with SCD and VTE. We recommend the use of antithrombotic prophylaxis or therapy in patients with SCD be evaluated in prospective studies.

Disclosures
No relevant conflicts of interest to declare.