Ordering of Home Hydroxyurea By Residents for Hospitalized Patients with Sickle Cell Disease
Authors: Shaw Rebekah , Kappa Sarah , Nickel Robert Sheppard 
Published: October 2019

Abstract
Background: Hydroxyurea is daily oral medication proven to decrease complications of sickle cell disease (SCD). While concerns have been raised about the safety of hydroxyurea, it is now generally viewed as a well-tolerated medication for SCD. The primary toxicity of hydroxyurea that requires holding of treatment is reversible cytopenia. Due to its classification as a chemotherapeutic agent and safety concerns regarding inappropriate chemotherapy ordering, hydroxyurea can only be ordered by "chemotherapy-certified" providers at some hospitals. At our hospital system, pediatric resident physicians were restricted from ordering hydroxyurea. Instead of being a part of a resident's hospital admission orders, hydroxyurea for inpatients had to be ordered separately by a hematology fellow or attending physician. In June 2016 our hospital changed its policy to allow residents to order hydroxyurea for patients with SCD admitted to the hospital who were already on hydroxyurea at home.
We hypothesized that this change in policy to allow residents to order hydroxyurea would increase the proportion of patients with SCD appropriately receiving their home hydroxyurea by hospital day 1. We also hypothesized that this policy change would not result in an increase in the proportion of patients inappropriately receiving hydroxyurea when it should have been held based on the admission complete blood count (CBC).
Methods: We conducted a retrospective review of the medical records of a random sample of patients admitted to the hematology service the year before (2015) and the year after (2017) the policy change in 2016. Patients were eligible for study if they were admitted to the hematology service and were taking hydroxyurea as documented by a clinic note within the last three months. Patients were excluded if they were admitted to the intensive care unit or for surgery. Patients were also excluded if discharged on hospital day 0 or 1. Institutional guidelines advise holding hydroxyurea if any of the following: absolute neutrophil count <1250/µL; platelet count <80K/µL; reticulocyte count <100K/µL, unless hemoglobin >8.0 gm/dL. Hydroxyurea was classified as "inappropriately given" if a patient received hydroxyurea despite having an admission CBC value below a hold parameter. Hydroxyurea was classified as "appropriately not given" if a patient did not receive hydroxyurea when having a CBC value below a hold parameter. Patients who were on hydroxyurea who never received hydroxyurea inpatient with CBC values above the hold parameters were classified as "inappropriately not given." Patients admitted in 2015 (before resident ordering) were compared with patients admitted in 2017 (after resident ordering) using a chi-square test or Fisher exact test.
Results: In total, 217 hospitalizations of eligible patients were reviewed: 91 before the policy change and 126 after the policy change. Based on the admission CBC, hydroxyurea should have been held for 8 patients. Excluding these patients who should not have received hydroxyurea, patients after the policy change were significantly more likely to have received their home hydroxyurea by hospital day 1: before 62/90 (69%) vs. after 105/119 (88%), p=0.0005. The proportion of patients who inappropriately received hydroxyurea was very low in both groups: before 1/91 (1%) vs. after 3/126 (2%), p=0.64. No serious adverse clinical events occurred from this "inappropriate" administration of hydroxyurea. The figure graphically displays the proportion of patients in the two groups who: appropriately received on hospital day 0/1/2+, inappropriately did not receive, appropriately did not receive, and inappropriately received hydroxyurea.
Conclusion: Resident ordering of home hydroxyurea for hospitalized patients with SCD appears to be safe. Policies that permit residents to order hydroxyurea as part of a patient's admission orders can help increase the proportion of patients who receive this important medication while inpatient.
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Disclosures
No relevant conflicts of interest to declare.