Documenting the Effectiveness of Hydroxyurea (HU) To Treat Sickle Cell Disease (SCD) in the Community Setting.
Authors: Lanzkron Sophie , Haywood Carlton , Fagan Peter 
Published: October 2019

Abstract
The benefits of HU for the treatment of adults with sickle cell anemia were confirmed by the multicenter study of hydroxyurea (MSH), the results of which were published in 1995. The purpose of this study was to investigate how HU is used outside of the research setting. We performed a retrospective analysis of five years of de-identified data (2001–2005) from a managed care organization (PP) serving the needs of patients on medical assistance in the State of Maryland. ICD-9 codes were used to identify patients that had SCD. Pharmacy data, outpatient visits, hospital admissions and LOS were examined using T-tests and Mann-Whitney tests and negative binomial regressions (relationship of total admissions to HU use). HU refill data was available on each patient for which it was prescribed. 390 people with SCD were covered over the time period. 97 were male and 293 were female. The mean age in 2001 was 29.2 yrs and 33.2 yrs in 2005. The majority of enrollees were adults. 350 of the 390 patients had an average age at or above 18 throughout their time in the data. 40 patients had an average age less than 18 throughout their time in the data. The mean number of months that the members were covered by PP was 33.4. There were1824 admissions for these 390 patients over the time period accounting for 8572 hospital days. Enrollees averaged 2 admissions per every 12 months enrolled in the plan. Mean LOS was 4.7 days. 41% of the inpatient hospital admissions were coded as readmissions. Mean readmission LOS was 4.7 days. Of the 390 patients, 335 never had a claim for an HU refill while 55 had at least one claim for an HU refill. A total of 158 individuals were admitted 2 or more times in any 12 month period and never had any HU refill claims. Males were more likely than females to have any HU use (22% vs. 12%, p=0.01). The mean number of HU fills for the time period for patients with any HU use was 10.7. On average, HU users had more months of enrollment in PP than non-HU users (41 vs 32, p=0.002). HU users had a higher admission per 12 month enrolled rate than non-HU users (5 vs. 1.5 admits per 12 months p=0.004). Among HU users, persons with 13 or more total refills for HU had a lower admit rate per 12 months than persons with 12 or less total refills (2.1 vs. 6.1, p=0.02). For HU users, each additional refill for HU received was associated with a 4% decrease in the expected hospitalization rate per member month, controlling for covariates (gender, mean age, and mean daily supply of medicine per refill).(p<0.001) There was no statistical difference in the mean number of outpatient visits for persons with 12 or less HU refills compared to persons with 13 or more. Mean medical costs per month enrolled in PP plan was as follows: $1524 for non-HU users, $4016 for HU users with 12 or less total refills of HU and $1611 for HU users with 13 or more total HU refills. There was no statistical difference in costs between the non-users and the users with 13 or more refills. These data show that those patients that received more HU refills, suggesting that they were taking HU on a regular basis, had a decrease in admissions to the hospital and markedly decreased costs. This validates the finding of the MSH in the community setting, patients that take HU are less likely to be admitted to the hospital and the use of HU on a regular basis can decrease costs.