Risks and Outcomes of Hospitalization in Patients with Chronic Lymphocytic Leukemia Admitted with Immune Thrombocytopenia: An Analysis of the National Inpatient Sample Database (2005-2019)

Background: Immune thrombocytopenia purpura (ITP) is a known complication of chronic lymphocytic leukemia (CLL). The treatment of ITP in CLL patients relies on steroids and intravenous immunoglobulin (IVIG). However, there is limited data regarding the risk CLL confers on hospitalization outcomes in patients admitted with ITP.

Method: For this retrospective study, we accessed data from the National Inpatient Sample (NIS) database. Using the International Classification of Disease, Ninth Revision, and Tenth Revision (ICD-9, ICD-10) codes, we identified hospitalizations for ITP and subclassified the data into hospitalizations with and without CLL, respectively (Figure 1). Chi-square and Mann-Whitney U tests were used to compare between categorical and continuous variables, respectively. Propensity score matching (PSM) was performed to account for potential confounding variables such as age, gender, race, admission type, and relevant comorbid conditions like coronary artery disease (CAD), chronic obstructive lung disease (COPD), chronic use of anticoagulants, and antiplatelet drugs, diabetes mellitus, hypertension, liver disease, obesity, and tobacco use. Furthermore, a secondary logistic regression model was utilized to control for median income, hospital characteristics, and insurance type in addition to the prior mentioned co-morbidities. We also compared the length of stay and total cost of hospitalization in patients with ITP with CLL to those without CLL.

Results: The data of 149,138 hospitalizations for ITP between 2005 to 2019 was gathered. Among those, 3552 (2.4%) hospitalizations were of patients with CLL (Figure 1). Unadjusted data revealed patients with CLL were older than ITP patients without CLL (72.6 years v 60.1 years, p<0.001), were more likely to be white (84.4 v 70.4%, p<0.001), and male (64.5% v 41.0%, p<0.001). CLL patients with ITP also had a significantly higher rate of co-morbidities like CAD (22.5% v 20.3%, p=0.002), liver disease (10.1% v 4.8%, p=0.001), hypothyroidism (15.7% v 14.4%, p=0.03), and chronic hypertension (56.1% v 52.6%, p<0.001). After PSM to account for these potential confounders, multivariate logistic regression showed that CLL patients with ITP had higher odds of needing a blood transfusion (odds ratio (OR)= 1.97, 95% CI: 1.74-2.25; p<0.001), platelet transfusion (OR= 1.45, 95% CI: 1.26-1.67; p<0.001), and IVIG (OR=1.41, 95% CI: 1.15-1.72, p<0.001). ITP patients with CLL also had a higher risk for GI bleed (OR=1.73, 95% CI: 1.34-2.24; p<0.001), splenectomy (OR= 1.49, 95% CI: 1.04-2.13; p=0.03), and all-cause mortality (OR=1.49, 95% CI: 1.18-1.88; p<0.001). There was no statistical difference between the risk of intracranial bleed or hypotensive episodes between the two groups. CLL patients with ITP also had a median higher length of stay (5 days v 4 days, p<0.001) and overall cost-of-hospitalization ($47,045 v $36,449; p<0.001) (Figure 1).

Conclusion: The hypothesis-generating results of this retrospective study suggest that despite balancing confounding variables, CLL patients with ITP have a higher risk of death, require more blood products, and have poorer hospitalization outcomes when compared with ITP patients without CLL. Further prospect studies can help determine whether refractoriness to conventional treatments for ITP in this subset of patients could account for these results.

Pinilla Ibarz:SecuraBio: Research Funding; AstraZeneca: Consultancy; AbbVie: Consultancy; Pharmacyclics: Consultancy; Janssen Pharmaceuticals: Consultancy. Jaglal:Sanofi: Consultancy; Novartis: Consultancy.