Hydroxyurea Adherence and Associated Outcomes in Medicaid Enrollees with Sickle Cell Disease.

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2483 Poster Board II-460 Background Laboratory and clinical benefits of hydroxyurea (HU) for patients with sickle cell disease (SCD) are well-established in the literature, with data drawn primarily from a few randomized trials and several single site observational studies. However, there is a paucity of data on the use of HU in real-world settings among SCD populations. Further, little research exists on the extent and implications of HU non-adherence among SCD patients. This study sought to assess the extent to which children and adults diagnosed with SCD (HbSS and HbSC) are adherent with prescribed HU therapy and potential associations between HU adherence and clinical and economic outcomes. Methods Retrospective claims of enrollees in the North Carolina Medicaid program (6/1999-8/2008) were analyzed. Inclusion criteria were ≥1 claim with a diagnosis for SCD (i.e., ICD-9-CM 282.6, 282.6x), continuous health plan enrollment for ≥12 months prior to and following HU initiation, and ≥2 HU prescriptions in the 12 months following HU initiation. Adherence was measured using the medication possession ratio (MPR), defined as the sum of days supplied with HU during the 12 months following HU initiation, divided by the number of days in the follow-up period (365), less the number of days hospitalized. Consistent with other studies of adherence, we considered MPR≥0.8 to be adherent. Multivariate regression analyses were used to estimate the association between HU adherence and economic and clinical outcomes (e.g., costs, likelihood of event) in the first year of therapy. In addition to the adherence indicator, covariates included age, gender, race, Charlson Comorbidity Index (CCI) score, and the number of SCD-related office visits in the year prior to HU initiation. Results 312 subjects (51% male, mean age [SD] 21 [12.2] years) met all inclusion criteria; 51% were '18 years old. The mean MPR was 0.60 (median=0.55), and only 35% of subjects were deemed adherent. Age, race and gender were similar across the adherent and nonadherent groups, while the nonadherent had a slightly higher (though low overall) CCI (0.68 vs. 0.35, p=0.0166) and more SCD-related office visits prior to HU initiation (18.0 vs. 10.6, p=0.0303). Multivariate regression models revealed that in the 12-months following HU initiation, treatment adherence was associated with a significant reduction in both all-cause and SCD-related inpatient (-$4,922, p=0.0010; -$4,383, p<0.0001, respectively) and ER costs (-$564, p=0.0010; -$420, p=0.0010, respectively), as well as SCD-related total costs (-$5,243, p=0.0010). Adherence was associated with an increase in SCD-related pharmacy costs (+$192, p<0.0001) and all-cause office visit costs (+$1,879, p=0.0370). Adherence was also associated with a reduced risk of SCD-related inpatient stay (hazard ratio [HR]=0.65, p=0.0343), ER visit, both all cause and SCD-related (HR=0.72, p=0.0447; HR=0.58, p=0.0080, respectively), and vaso-occlusive event (HR=0.66, p=0.0130). As a sensitivity analysis, we lowered the adherence threshold to ≥0.6; 48% would then be considered adherent. Significant economic benefits (i.e., all-cause and SCD-related inpatient and ER costs; SCD-related total costs) of adherence at the '0.8 threshold were no longer statistically significant using the ≥0.6 definition, but adherence at the lower threshold was still associated with a significant reduced risk of SCD-related ER visits and vaso-occlusive events. Conclusions Adherence to HU in patients with SCD may be suboptimal. Adherence to HU is associated with improved outcomes, both clinical and economic. Disclosures Off Label Use: Hydroxyurea is approved for adults with sickle cell disease. We will be discussing its use in pediatric and adult patients..

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... The results are again similar to the study by Kauf et al. that found 64% of costs were SCD-related [16]. HU adherence among SCD patients has also been associated with decreased risk of SCDrelated hospitalization, all-cause and SCD-related ER visits, and vaso-occlusive events [32,42]. In addition, the difference in all-cause health care resource utilization in the baseline and follow-up periods showed a decrease in all-cause hospitalization, inpatient LOS, and outpatient ER visits. ...
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Background: This study aimed to evaluate sickle-cell disease (SCD) treatment patterns and economic burden among patients prescribed hydroxyurea (HU) in the US, through claims data. Methods: SCD patients with pharmacy claims for HU were selected from the Medicaid Analytic Extracts (MAX) from January 1, 2009 - December 31, 2013. The first HU prescription during the identification period was defined as the index date and patients were required to have had continuous medical and pharmacy benefits for ≥6 months baseline and 12 months follow-up periods. Patient demographics, clinical characteristics, treatment patterns, health care utilization, and costs were examined, and variables were analyzed descriptively. Results: A total of 3999 SCD patients prescribed HU were included; the mean age was 19.24 years, most patients were African American (73.3%), and the mean Charlson comorbidity index (CCI) score was 0.6. Asthma (20.3%), acute chest syndrome (15.6%), and infectious and parasitic diseases (20%) were the most prevalent comorbidities. During the 12-month follow-up period, 58.9% (N = 2357) of patients discontinued HU medication. The mean medication possession ratio (MPR) was 0.52, and 22.3% of patients had MPR ≥80%. The average length of stay (LOS) for SCD-related hospitalization was 13.35 days; 64% of patients had ≥1 SCD-related hospitalization. The mean annual total SCD-related costs per patient were $27,779, mostly inpatient costs ($20,128). Conclusions: Overall, the study showed the patients had significant unmet needs manifest as poor medication adherence, high treatment discontinuation rates, and high economic burden.
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