Clinical and Economic Outcomes Associated with Emergency Department Visits in Patients with Immune Thrombocytopenia,
Authors: Lu Z John , Danese Mark D. , Halperin Marc , Eisen Melissa , Deuson Robert 
Published: October 2019

Abstract
Abstract 4209

Introduction:
Immune thrombocytopenia (ITP) is characterized by low platelet counts, spontaneous bruising, mucosal bleeding, and, more seriously, intracranial hemorrhage. The disease is associated with a high risk of complications, often requiring visits to emergency departments (ED), with possible subsequent hospitalization. To date, information about ED visits in ITP patients, including frequency, cost, hospitalization risk, and mortality risk, has not been well documented, although such data are critical to the understanding of the clinical and financial implications of poorly-controlled, chronic ITP. We used the 2007 Nationwide Emergency Department Sample (NEDS) to examine resource utilization, ED visits, and hospitalization charges in the US. Methods: The 2007 NEDS contains about 27 million ED records from over 970 hospitals in 27 Healthcare Cost and Utilization Project (HCUP) Partner States, representing a 20% stratified sample of US hospital-based ED visits. The database includes hospital and patient characteristics, diagnoses and procedures, disposition from ED including hospitalization and mortality, discharge diagnosis-related group (DRG) for subsequent hospitalizations, and total charges. Its large sample size enables analyses of relatively rare conditions such as ITP. All ED visits in the database were separated into two groups: visits with ITP as one of the diagnoses (ICD-9-CM diagnosis code of 287.31), and those without a diagnosis of ITP. Outcomes and resource use were separately evaluated in these two groups, as well as in several subgroups within the ITP group defined by age and whether the ITP diagnosis was the primary or a secondary diagnosis. Results: Approximately 8,348 (∼0.03%) of all ED visits in the 2007 NEDS database were in patients with ITP (28% as the primary diagnosis), of which nearly 60% were by female patients and 88% by adult patients (≥18 years old). Medicare or Medicaid was listed as the primary payer in 58% of the visits. Seventy-five percent of the ED visits in ITP patients led to hospitalizations, compared with less than 16% of ED visits in non-ITP patients (p < 0.0001). In ITP patients, 3% of the ED visits ended in death, compared with 0.6% in non-ITP patients (p < 0.0001). The mean total charges for ED visits in ITP patients were $1,650 compared with $1,495 for all others (p<0.0001). The average length of stay (LOS) during hospitalizations subsequent to ED visits was >1.5 days longer (6.5 vs. 5.0 days; p < 0.0001) for ITP patients. The mean total combined charges during the ED visit and resulting hospitalization were >60% higher ($47,000 vs. $29,000; p < 0.0001) for ITP patients. Subgroup analyses of ED visits in ITP patients by age showed that in the majority of visits by pediatric patients (<18 years old), ITP was identified as the primary diagnosis (61%) compared with only 24% among visits by adult patients. Furthermore, visits by adult ITP patients were less likely to result in routine discharge (18% vs. 50%), more likely to result in hospitalization (80% vs. 43%), and were associated with higher mortality compared with pediatric ITP patients (4% vs. 0.1%; p < 0.0001 for all comparisons). ED visits identified with ITP as the primary diagnosis were associated with a higher rate of subsequent hospitalizations (81% vs. 73%), but lower total charges and mortality ($1,490 vs. $1,710, and 2% vs. 4%) respectively, compared with those identified with ITP as a secondary diagnosis (p < 0.0001 for all comparisons). Conclusion: ED visits in ITP patients were associated with significantly worse outcomes, higher resource utilization, and greater total charges. For patients with ITP, younger age and a primary diagnosis of ITP were generally associated with better outcomes following ED visits. More robust and rigorous analyses controlling for patient and hospital heterogeneities will be conducted to confirm these findings.

Disclosures:
Lu: Amgen: Consultancy, Equity Ownership, Research Funding. Danese:Amgen: Consultancy, Research Funding. Halperin:Amgen: Consultancy, Research Funding. Eisen:Amgen: Employment, Equity Ownership. Deuson:Amgen: Employment, Equity Ownership.