Association of Inpatient Opioid Utilization and Readmission Risk in Sickle Cell Disease
Authors: Han Jin , Saraf Santosh L. , Gowhari Michel , Jain Shivi , Molokie Robert E. , Gordeuk Victor R. 
Published: October 2019

Abstract
Background: Vaso-occlusive crisis (VOC) is the hallmark complication of sickle cell disease (SCD). The majority of SCD-related healthcare costs in the United States, estimated at $2.4 billion annually, are attributed to frequent healthcare utilization due to recurrent VOC (1-3). Risk factors such as the prescription of nonsteroidal anti-inflammatory drugs (NSAIDs) only without opioids, older age, and steroid treatment have been identified to be associated with readmissions in pediatric SCD patients (4, 5), but limited data exist about potential predictors for readmission in adults (6). The impact of inpatient opioid utilization on readmission was evaluated in this study.
Methods: Seventy SCD adults treated at the University of Illinois Hospital from 2012-2016 had at least one hospitalization for uncomplicated VOC that was followed by a 30-day readmission (30-DR) and at least one hospitalization without a 30-DR. One hospitalization with a 30-DR and one hospitalization without a 30-DR from each patient were used to form the discovery cohort (a total of 140 hospitalizations from 70 unique patients). Patient characteristics, inpatient laboratory values, outpatient daily opioid use before admission, and inpatient daily opioid use were collected from the electronic medical records, and the ratio of the last inpatient day opioid dose/home opioid dose before admission was calculated. Among the 70 patients in the discovery cohort, 22 patients had more than one hospitalization with a 30-DR. The additional hospitalizations with a 30-DR and matched hospitalizations from the same patient without a 30-DR were used to form a validation cohort (a total of 62 hospitalizations from 22 unique patients). A Wilcoxon signed-rank test was performed to compare the ones with a 30-DR to the ones without. The study was approved by the Institutional Review Board prior to the initiation of chart review.
Results: Among the 70 SCD patients identified, the median (IQR) age was 32.5 (25-44) years by the time of the first admission included in this cohort, and 67% were females, 76% were HbSS or Sbeta0 genotype, and 46% were on hydroxyurea before admission. The median (IQR) dose of daily outpatient opioids before the first admission was 170 (64-280) mg oral morphine equivalents (OME). When the hospitalizations without a 30-DR were compared to the ones with in the discovery cohort (Table 1), the ratio of last inpatient day opioid dose/home opioid dose was lower (1.5 vs. 1.9, p=0.024), whereas other relevant clinical variables including length of stay, pain score upon discharge, and hemoglobin or WBC upon discharge were not significantly different between the two groups (Table 1). The proportion of patients who used patient controlled analgesia (PCA) during admission, or underwent opioid dose tapering during hospitalizations, or converted IV opioids to oral ones before discharge was also comparable. In the validation cohort (Table 1), the ratio of last inpatient day opioid dose/home opioid dose in the group without a 30-DR was also lower than the ones with a 30-DR (1.4 vs. 2.0, p=0.033), whereas other clinical variables were comparable.
Summary: Here we showed that a high ratio of last inpatient day opioid dose/home opioid dose is associated with readmission risk for sickle cell patients treated for uncomplicated VOC. The results suggest that proper tapering of inpatient opioid dose in reference to patient's home opioid dose before discharge may reduce the readmission risk.
Reference: K. L. Hassell, Am J Prev Med38, S512 (Apr, 2010). S. Lanzkron, C. P. Carroll, C. Haywood, Jr., Am J Hematol85, 797 (Oct, 2010). T. L. Kauf, T. D. Coates, L. Huazhi, N. Mody-Patel, A. G. Hartzema, Am J Hematol84, 323 (Jun, 2009). L. M. Okorji, D. S. Muntz, R. I. Liem, Pediatr Blood Cancer64, (May, 2017). A. Sobota, D. A. Graham, E. J. Neufeld, M. M. Heeney, Pediatr Blood Cancer58, 61 (Jan, 2012). M. A. Brodsky et al., Am J Med130, 601 e9 (May, 2017).

Disclosures
No relevant conflicts of interest to declare.