Frequency of Emergency Department Visits for Sickle Cell Disease Vaso-Occlusive Crisis and Its Contribution to Hospital Admission Rates
Authors: Loeffler Patrick , Mueller Taylor , Kutlar Abdullah , Gibson Robert , Sturgis LaShon , Lyon Matthew 
Published: October 2019

Abstract
Background: Patients with sickle cell disease (SCD) vaso-occlusive crisis (VOC) frequently seek care in the emergency department (ED). To improve and increase consistency of care patients with uncomplicated VOC, are treated in the Emergency Department Observation Unit (EDOU) where they are treated with an individualized protocol-based pathway. EDOUs have been shown to be effective in meeting treatment guidelines and reducing hospital admission.
Objective: This study examines the admission rates of individuals with SCD stratified by frequency of presentation at the EDOU.
Methods: A retrospective review of an ED database was completed to explore the relationship between EDOU utilization and admission rate for patients with uncomplicated VOC. All patient records meeting pathway inclusion criteria for uncomplicated VOC during the time period September 2013 through May 2015 were included in the study. Visits were first associated with individual patients. Then, based on the number of visits per time period, patients were categorized as high users, moderate users, or low users. Categorization was done using the number of visits during the first, 12-month period (9/11/13 - 9/10/14), or the second, nine-month period (9/10/14 - 5/31/15). Adaptations to the categorization scheme for the nine-month time period were as follows. Low users were patients that had no more than one visit in either the first or second time period; moderate users were patients with two or three visits in the first time period or two visits in the second; high users were patients with four or more visits in the first time period, or three or more visits in the second time period. Admission rates were calculated as percentages of visits to the EDOU. Rates of admission for high, middle, and low users were compared using an unpaired, one-tailed Student's t-test. This study was approved by expedited review by the institution's Institutional Review Board (IRB).
Results: A total of 727 visits for 154 patients were included in the analysis. High users (n=44) had a total of 539 visits and an average patient admission rate of 22% (n=118). Moderate users (n=49) had a total of 108 visits and an admission rate of 31% (n=33). Low users (N=61) had a total of 80 visits and an admission rate of 36% (n=29). The difference between the number of high user admissions and low user admissions was significant (p<0.01) as was the difference between the number of moderate-user visits and the number of high-user visits (p=0.04). The difference between the number of moderate and low user admissions was not significant (p=0.14).
Conclusion: This study found that the difference in the number of admissions between high and low users and between high and moderate users was significant. The findings provide support for the value of the EDOU in reducing unnecessary hospital admissions. These findings also raise important questions regarding the phenotypic expression of pain in SCD and the availability of care. Although the criteria for categorization of patients in this study was limited and the time periods unequal the results suggest different patterns of personal response to pain and treatment seeking. It is unknown how these groups may be different in regards to access to care, treatment preferences, self-care practices, or severity of disease. It can be hypothesized from these results that there may be two different patterns of care seeking with some patients only using the EDOU when crisis is severe (low users) and other patients (high users) using the EDOU as part of their regular pain treatment strategy. To address these questions it is necessary to further examine the differences between these groups to look for explanations that can address increased utilization of the EDOU among some patients.

Disclosures
No relevant conflicts of interest to declare.