Quantifying Social Disadvantage for Patients with Sickle Cell Disease: Implications for Quality of Care
Authors: Savidge Nicole , Parsons Susan K , Mao Daqin , Weidner Ruth Ann , Esham Kimberly S , Rodday Angie Mae 
Published: October 2019

Abstract
Background: Socioeconomic disadvantage negatively affects healthcare utilization and disease outcomes. The Area Deprivation Index (ADI) is a well-established method for quantifying socioeconomic disadvantage that combines 17 US Census block indicators of poverty, education, housing, and employment (Singh Am J Public Health. 2003). ADI scores have been shown to be associated with hospital readmission and mortality in the general population and in chronic diseases, such as diabetes (Kind et al. Ann Intern Med. 2014). However, the ADI has not been used in patients with sickle cell disease (SCD), a group that faces health disparities based on race and socioeconomic status and that has high healthcare utilization, including a 41% readmission rate among young adults (Brousseau et al. JAMA. 2010). We applied the ADI to patients with SCD, hospitalized for vaso-occlusive crisis (VOC). We described patient, disease, and treatment characteristics by high and low ADI scores.
Methods: This retrospective cohort study includes 449 consecutive hospitalizations for VOC among 63 adult patients (≥18 years) with SCD from 2013-2016 at an urban, US-based academic medical center. For this analysis, one hospitalization was randomly selected for each patient. Demographics, including street address, SCD characteristics, complications, treatment, hospital entry and discharge pain scores, length of stay and 30-day readmission were abstracted from electronic medical records (EMR) by trained study staff. History of SCD complications (e.g., acute chest syndrome, avascular necrosis) were reviewed by two hematologists.
The 2013 Massachusetts (MA) ADI dataset was used to assign patients an ADI decile value based on the census block corresponding to the patient-reported address in the EMR (https://www.neighborhoodatlas.medicine.wisc.edu/). ADI deciles were calculated using ADI scores from all census blocks in MA ranked from lowest to highest (1-10), where higher scores indicate more deprivation. ADIs were divided into a more disadvantaged group and a less disadvantaged group at the sample median similar to previous research (Hu et al. Am J Med Qual. 2018). Summary statistics described patient and disease characteristics separately by these groups.
Results: Out of the 63 patients in our cohort, the ADI was calculated for the 57 patients who had a valid MA address (90.5%). The median age was 26 years with 56.1% female and 77.2% black (Table). The majority of patients were publicly insured (28.1% Medicare, 66.7% Medicaid), while only 5.3% were privately insured. The most common genotype was Hemoglobin (Hb) SS (61.4%), followed by Hb SC (22.8%). The median MA ADI rank was 6; 27 patients (47.4%) were classified as less disadvantaged and 30 (52.6%) as more disadvantaged.
Among the less disadvantaged group, 88.9% were black and 11.1% were Hispanic, while the more disadvantaged group was 66.7% black and 30.0% Hispanic. The less disadvantaged group had fewer Medicaid patients (59.3%) than the more disadvantaged group (73.3%). Hb SS genotype was more common in the less disadvantaged group (70.4%) than the more disadvantaged group (53.3%), where there were more patients with Hb SC (30.0%). For treatment and management, the less disadvantaged group had more patients prescribed hydroxyurea (74.1%) and home opioids (92.6%), compared to the more disadvantaged group (56.7% hydroxyurea; 80.0% home opioids). Length of hospital stay and pain scores were similar across the two groups. The 30-day readmission rate was 14.8% for the less disadvantaged group and 23.3% for the more disadvantaged group.
Conclusions: We successfully applied a validated measure of socioeconomic disadvantage to a cohort of hospitalized patients with SCD. The more disadvantaged group consisted of more Hispanic patients with less Hb SS genotype and more Medicaid insurance. Further, there appeared to be differences in SCD management and readmissions by group, indicating possible disparities and opportunities to improve care and outcomes. Based solely on a patient's address from the EMR, the ADI can be used at the point of care to identify and ensure that the most vulnerable patients are receiving appropriate levels of social support. Given that SCD is referred to as a disease of double disadvantage, it is crucial to understand the intersection of this debilitating chronic illness within the context of socioeconomic disadvantage.

Disclosures
Parsons: Seattle Genetics: Research Funding. Rodday:Seattle Genetics: Research Funding.