Examining community-level social vulnerability and emergency department use for people living with sickle cell disease in Michigan.

This study examined associations between emergency department (ED) visits and social vulnerability index (SVI) among Michigan's population with sickle cell disease (SCD) using data from the Michigan Sickle Cell Data Collection program (n = 3658 in 2018). SVI was higher among census tracts where people with SCD resided (mean SVI = 0.67; SD = 0.27) compared to census tracts without SCD residents (mean SVI = 0.39; SD = 0.25; p < .001). For children with SCD, for every 0.1 increase in SVI score, the number of ED visits increased by 6% (IRR = 1.061; SE = 0.03; p = .038). Future research should investigate the association between SVI and ED use, at the community and household levels, to elucidate strategies to reduce ED use among children with SCD.

Patterns of primary and specialty care among children with sickle cell anemia.

BACKGROUND AND OBJECTIVE: National guidelines recommend that children with sickle cell anemia (SCA) be seen regularly by primary care providers (PCPs) as well as hematologists to receive comprehensive, multidisciplinary care. The objective is to characterize the patterns of primary and hematology care for children with SCA in Michigan. METHODS: Using validated claims definitions, children ages 1-17 years with SCA were identified using Michigan Medicaid administrative claims from 2010 to 2018. We calculated the number of outpatient PCP and hematologist visits per person-year, as well as the proportion of children with at least one visit to a PCP, hematologist, or both a PCP and hematologist annually. Negative binomial regression was used to calculate annual rates of visits for each provider type. RESULTS: A total of 875 children contributed 2889 person-years. Of the total 22,570 outpatient visits, 52% were with a PCP and 34% with a hematologist. Annually, 87%-93% of children had a visit with a PCP, and 63%-85% had a visit with a hematologist. Approximately 66% of total person-years had both visit types within a year. The annual rate ranged from 2.3 to 2.5 for hematologist visits and from 3.7 to 4.1 for PCP visits. CONCLUSIONS: Substantial gaps exist in the receipt of annual hematology care. Given that the majority of children with SCA see a PCP annually, strategies to leverage primary care visits experienced by this population may be needed to increase receipt of SCA-specific services.

Adherence to hydroxyurea and clinical outcomes among children with sickle cell anemia.

OBJECTIVE: Hydroxyurea lowers the incidence of vaso-occlusive pain crises (VOC) and acute chest syndrome (ACS) among children with sickle cell anemia (SCA). Our objective was to assess the relationship between levels of adherence to hydroxyurea and clinical outcomes among children and adolescents with SCA. METHODS: This retrospective cohort study included Medicaid data (2005-2012) from Florida, Illinois, Louisiana, Michigan, South Carolina, and Texas. The study population consisted of children 1-17 years old with SCA enrolled in Medicaid for 3 years. Among children that initiated hydroxyurea, the medication possession ratio (MPR) was calculated as the proportion of days covered by hydroxyurea. Six months after initiation of hydroxyurea, clinical outcomes were assessed through the end of the study period: numbers of VOC-related inpatient admissions and emergency department visits, and encounters for ACS. Multivariable Poisson models were used to predict outcomes by MPR quartile adjusting for previous healthcare utilization, state, and age. RESULTS: Hydroxyurea was initiated by 515 children. The median MPR was 0.53 (interquartile range = 0.3-0.8). The annual median number of visits was 0.0 for ACS, 1.3 for VOC-related emergency department, and 1.4 for VOC-related inpatient admissions. For each outcome, the highest quartile of MPR had the lowest predicted count; this difference was significant for ACS visits when compared with the lowest quartile of MPR. CONCLUSION: This study demonstrated a high level of adherence (>75%) was essential to achieve a lower incidence of common negative clinical outcomes. Further, moderate and severe hydroxyurea nonadherence may be more common than previously appreciated among children, emphasizing the importance of developing and testing innovative strategies to increase adherence.

Trends in quality of care among children with sickle cell anemia.

INTRODUCTION: For decades, it has been recommended that children with sickle cell anemia (SCA) receive antibiotic prophylaxis to prevent serious infections and undergo transcranial Doppler (TCD) screening to identify those at highest risk of overt stroke. We assessed recent temporal trends in antibiotic prophylaxis prescription fills and TCD screening among children with SCA using validated quality measures. PROCEDURE: Using validated claims-based definitions, we identified children with SCA who were enrolled in Michigan or New York State (NYS) Medicaid programs (2011-2018). Among recommended age groups, two outcomes were assessed yearly: (a) filling of ≥300 days of antibiotics, and (b) receipt of greater than or equal to one TCD. The proportion of children with each outcome was calculated by state. Temporal trends in each preventive service were assessed using generalized linear models. RESULTS: A total of 1784 children were eligible for antibiotic prophylaxis (Michigan: 384; NYS: 1400), contributing 3322 person-years. Annual rates of filling ≥300 days of antibiotics ranged from 16% to 22% and were similar by state. There was no change in rates of antibiotic filling over time in Michigan (p-value: .10), but there was a decrease in NYS (p-value: .02). A total of 3439 children with SCA were eligible for TCD screening (Michigan: 710; NYS: 2729), contributing 10,012 person-years. Annual rates of TCD screening ranged from 39% to 45%, were similar by state, and did not change over time (p-values >.05). CONCLUSIONS: Most children with SCA do not receive recommended antibiotic prophylaxis and/or TCD screening. New, sustainable, and coordinated interventions across preventive services are urgently needed.

The Impact of Sickle Cell Anemia and Mental Health Diagnoses on Healthcare Use and Preventive Care among Children Enrolled in Medicaid, 2005-2012.

OBJECTIVE: To examine mental health diagnoses, healthcare use, and receipt of age-appropriate preventive care, including antibiotic prophylaxis, hydroxyurea therapy, and transcranial Doppler screenings, among children with sickle cell anemia (SCA). STUDY DESIGN: Children aged 1-17 years with SCA from 6 states having 3 or more Medicaid claims with a SCA diagnosis within a year (2005-2012) were included. Children with mental health diagnoses were identified with 1 or more mental health encounters. Poisson and logistic regression models with general estimating equations assessed the relationship between mental health diagnoses, healthcare use, and receipt of age-appropriate preventive care. RESULTS: In total, 7963 children with SCA were identified (22 424 person-years); 1593 person-years (7.1%) included 1 or more mental health diagnoses. Children with a mental health diagnosis were more likely to have inpatient admissions (incidence rate ratio [IRR] 1.46, 95% CI 1.36-1.56) and outpatient (IRR 1.27, 95% CI 1.21-1.34), emergency department (IRR 1.39, 95% CI 1.30-1.48), and well-child visits (IRR 1.19, 95% CI 1.11-1.29). Those with a mental health diagnosis were more likely to receive hydroxyurea therapy (odds ration [OR] 1.17, 95% CI 1.03-1.33) and less likely to receive transcranial Doppler screenings (OR 0.79, 95% CI 0.68-0.93). CONCLUSIONS: Children with SCA do not receive adequate age-appropriate preventive care. Further research is necessary to identify key points of coordination between mental health and SCA services throughout the life course. This approach may help to increase receipt of age-appropriate preventive care and decrease reliance on acute care.

Hydroxyurea use among children with sickle cell anemia.

This study describes hydroxyurea use among children ages 1 to 17 with sickle cell anemia (SCA) enrolled in at least one year of Medicaid in six states from 2005 to 2012. Administrative claims were used to summarize the number of days' supply of hydroxyurea dispensed by state and year. A total of 7963 children with SCA contributed 22 424 person-years. Among person-years with greater than 30 days of hydroxyurea, only 18% received at least 300 days of hydroxyurea, which varied by state. Following updated recommendations for all children with SCA to be offered hydroxyurea, strategies to increase hydroxyurea adherence among this population are needed.

Pneumococcal vaccination coverage among children with sickle cell anemia, sickle cell trait, and normal hemoglobin.

BACKGROUND: Children with sickle cell anemia and sickle cell trait are at an increased risk of invasive pneumococcal disease compared to children with normal hemoglobin. We assessed and compared pneumococcal vaccination status among these three groups. PROCEDURE: Children with sickle cell anemia and sickle cell trait were identified using Michigan newborn screening records (1997-2014); each child was matched to four children with normal hemoglobin based on age, Medicaid enrollment (at least 1 year from 2012-2014), race, and census tract. Vaccination records were obtained from the state's immunization system. Pneumococcal vaccine coverage (PCV7 or PCV13 depending on date of administration) was assessed at milestone ages of 3, 5, 7, and 16 months. The proportion of children with vaccine coverage at each milestone was calculated overall and compared among children with sickle cell anemia, sickle cell trait, and normal hemoglobin using chi-square tests. RESULTS: The study population consisted of 355 children with sickle cell anemia, 17,319 with sickle cell trait, and 70,757 with normal hemoglobin. The proportion of children with age-appropriate pneumococcal vaccination coverage was low at each milestone and generally decreased over time. Children with sickle cell anemia were more likely to be covered compared to children with sickle cell trait or normal hemoglobin. CONCLUSIONS: Despite higher pneumococcal vaccination coverage among children with sickle cell anemia, opportunities for improvement exist among all children. Targeted interventions will benefit from mechanisms to identify children with increased risks such as sickle cell anemia or trait to improve pneumococcal vaccination coverage among these groups.

Perianal Crohn Disease in a Large Multicenter Pediatric Collaborative.

BACKGROUND: Although perianal complications of Crohn disease (CD) are commonly encountered in clinical practice, the epidemiology of perianal CD among populations of children is poorly understood. We sought to characterize the prevalence of perianal disease in a large and diverse population of pediatric patients with CD. METHODS: We conducted retrospective analyses from a prospective observational cohort, the ImproveCareNow Network (May 2006-October 2014), a multicenter pediatric inflammatory bowel disease quality improvement collaborative. Clinicians prospectively documented physical examination and phenotype classification at outpatient visits. Perianal examination findings and concomitant phenotype change were used to corroborate time of new-onset perianal disease. Results were stratified by age, sex, and race and compared across groups with logistic regression. Cumulative incidence was estimated using Kaplan-Meier analyses and compared between groups with Cox proportional hazard regression models. RESULTS: The registry included 7076 patients with CD (41% girls). Missing/conflicting entries resulted in 397 (6%) patient exclusions. Among the remaining 6679 cases, 1399 (21%) developed perianal disease. Perianal disease was more common among boys (22%) than girls (20%; P = 0.013) and developed sooner after diagnosis among those with later rather than early onset disease (P < 0.001). Perianal disease was also more common among blacks (26%) compared with whites (20%; P = 0.017). Asians with later onset CD developed perianal disease earlier in their disease course (P = 0.01). There was no association between disease location or nutritional status at diagnosis and later development of perianal disease. CONCLUSIONS: In this large multicenter collaborative, we found that perianal disease is more common among children with CD than previously recognized. Differences in the development of perianal disease were found across racial and other subgroups. Treatment strategies are needed to prevent perianal disease development.

The role of neighborhoods in the receipt of transcranial Doppler screening among children with sickle cell disease.

Although transcranial Doppler (TCD) screening assesses the need for stroke prevention efforts among children with sickle cell disease (SCD), screening rates remain low across many parts of the United States. We sought to identify neighborhoods with low TCD screening rates and neighborhood-level factors related to screening to inform the utility of community-level interventions to improve TCD screening. Children ages 2 to 16 years with SCD (HbSS/HbS/ß-thalassemia) living in Wayne County, MI, were identified in Michigan Medicaid (2007 to 2011) through newborn screening records. Children were enrolled for ≥ 1 year and could contribute multiple years. We determined receipt of ≥ 1 TCD screening and neighborhood (census tract) each year. The proportion of children receiving TCD in the tract was calculated and investigated for spatial patterns across tracts (Moran's I). Median household income, % unemployment, % black residents, and % less than high school education within each tract were ascertained from the American Community Survey. Logistic regression with generalized estimating equations was used to model associations between TCD screening and neighborhood-level factors. Overall, 329 children contributed 532 person-years and screening rates increased from 7% to 36% from 2007 to 2011. Median screening rate in tracts was 0% (interquartile range = 29%) and there was no spatial pattern of TCD screening across tracts (Moran's I Z-score = -0.94, P-value = 0.35). No associations were found between neighborhood characteristics and receipt of TCD screening in this disadvantaged Michigan county. Additional research is needed to inform interventions to increase TCD screening in this high stroke-risk population.

Statewide pandemic influenza vaccination reminders for children with chronic conditions.

OBJECTIVES: We evaluated the use of a statewide immunization information system (IIS) to target influenza vaccine reminders to high-risk children during a pandemic. METHODS: We used Michigan's IIS to identify high-risk children (i.e., those with ≥ 1 chronic condition) aged 6 months to 18 years with no record of pH1N1 vaccination among children currently or previously enrolled in Medicaid (n = 202,133). Reminders were mailed on December 7, 2009. We retrospectively assessed children's eligibility for evaluation and compared influenza vaccination rates across 3 groups on the basis of their high-risk and reminder status. RESULTS: Of the children sent reminders, 53,516 were ineligible. Of the remaining 148,617 children, vaccination rates were higher among the 142,383 high-risk children receiving reminders than among the 6234 high-risk children with undeliverable reminders and the 142,383 control group children without chronic conditions who were not sent reminders. CONCLUSIONS: Midseason reminders to parents of unvaccinated high-risk children with current or past Medicaid enrollment were associated with increased pH1N1 and seasonal influenza vaccination rates. Future initiatives should consider strategies to expand targeting of high-risk groups and improve IIS reporting during pandemic events.

Pneumococcal vaccination rates in children with sickle cell disease.

CONTEXT: Sickle cell disease (SCD) confers an increased risk of invasive pneumococcal disease, especially among young children. Pneumococcal vaccination decreases this risk, but the completion rate of age-appropriate vaccinations is not well defined in SCD. OBJECTIVE: The goal of this study was to assess whether pneumococcal vaccines are administered to high-risk children with SCD according to recommended vaccine schedules. DESIGN: A case-control design was used to conduct this study. SETTING: Administrative data were obtained on Michigan Medicaid or Children's Special Health Care Services programs enrollees. In addition, Michigan Newborn Screening and Michigan Care Improvement Registry records were used to confirm diagnosis and vaccine administration. PARTICIPANTS: This study compared pneumococcal vaccination rates in a cohort of 179 children with SCD with 537 age-matched non-SCD controls (1:3) enrolled in the Michigan Medicaid Program between 2001 and 2008. Study subjects were born in the state of Michigan between 2001 and 2005. MAIN OUTCOME MEASURE: The main outcome measure was the proportion of children defined as up to date for pneumococcal vaccines at defined milestone ages. RESULTS: Children with SCD had significantly higher vaccination rates than controls, yet these values were much lower than state and national immunization survey rates. CONCLUSION: Barriers to completing age-appropriate recommended pneumococcal immunizations should be identified and addressed to further reduce invasive pneumococcal disease in this high-risk patient population.

TCD screening and spending among children with sickle cell anemia.

OBJECTIVES: National guidelines recommend that children with sickle cell anemia receive annual transcranial Doppler (TCD) screening to assess stroke risk. Our objectives were to estimate the rate of TCD screening among privately insured children with sickle cell anemia, estimate out-of-pocket spending for TCD screening, and evaluate the association between TCD screening and enrollment in high-deductible health plans (HDHPs). STUDY DESIGN: Cross-sectional. METHODS: Using the 2009-2017 IBM MarketScan Commercial Database, we identified children aged 2 to 15 years who met a validated claims-based definition of sickle cell anemia. We calculated the proportion of children receiving annual TCD screening and out-of-pocket spending per TCD screen. Using logistic regression with generalized estimating equations, we modeled the receipt of annual TCD screening as a function of HDHP enrollment, controlling for demographics and year. RESULTS: The 2519 children in the analysis accounted for 7197 person-years of enrollment; 14% of person-years were from HDHP enrollees. During 2009-2017, the proportion of children receiving TCD screening ranged from 40% to 44%. Median out-of-pocket spending for TCD screening was $20 overall and $65 among HDHP enrollees. Out-of-pocket spending exceeded $100 for 27% of all screens and 42% of screens among HDHP enrollees. HDHP enrollment was not associated with TCD screening (adjusted odds ratio, 0.99; 95% CI, 0.85-1.15). CONCLUSIONS: Among privately insured children with sickle cell anemia, fewer than half received annual TCD screening. Out-of-pocket spending exceeded $100 for 27% of TCD screens. Although HDHP enrollment was not associated with TCD screening, additional studies are needed to assess whether cost sharing might deter this screening.

Changes in Hydroxyurea Use Among Youths Enrolled in Medicaid With Sickle Cell Anemia After 2014 Revision of Clinical Guidelines.

Importance: Youths with sickle cell anemia (SCA) are at risk of pain crises, stroke, and early death. Complications can be reduced by the oral disease-modifying medication hydroxyurea, and in 2014, the National Heart, Lung, and Blood Institute published revised guidelines that hydroxyurea should be offered to youths aged 9 months and older with SCA regardless of disease severity. Objective: To describe changes in hydroxyurea use among youths with SCA before and after release of the National Heart, Lung, and Blood Institute guidelines. Design, Setting, and Participants: This cross-sectional study was conducted using administrative data from 2010 to 2018 from Michigan and New York State (NYS) Medicaid programs. The study population included youths aged 1 to 17 years with SCA enrolled in the Michigan or NYS Medicaid programs for at least 1 year (Michigan: 2010-2018; NYS: 2012-2018). Youths with SCA were identified using validated claims-based definitions. Data were analyzed from June to October 2020. Main Outcomes and Measures: The main outcome was hydroxyurea use characterized as mean annual counts of days' supply of filled hydroxyurea prescriptions. Rates of hydroxyurea use over time were assessed using regression models (Michigan: zero-inflated negative binomial; NYS: negative binomial). Models included indicators for periods before and after guideline release. Results: A total of 4302 youths with SCA (2236 males [52.0%]; 2676 born 2005-2017 [62.2%]; 150 Hispanic [3.5%], 2929 non-Hispanic Black [68.0%], and 389 non-Hispanic White [9.0%]) contributed 12 565 person-years. The mean (SD) annual days' supply of hydroxyurea was 47.2 (93.6) days per youth in Michigan and 97.4 (137.0) days per youth in NYS. In Michigan, there was an increase in the odds of having nonzero days' supply after the guidelines were released (odds ratio, 1.52; 95% CI, 1.07-2.14). In NYS, no change was seen in the mean days' supply of filled hydroxyurea. Conclusions and Relevance: These findings suggest that hydroxyurea was substantially underused among youths with SCA, despite establishment as the primary disease-modifying therapy for SCA, and that there was incomplete clinician or patient uptake of newly released guidelines. Results suggest that expanding use of hydroxyurea may require a multifaceted approach that includes addressing multiple system- and patient-level barriers.

Understanding attitudes toward adolescent vaccination and the decision-making dynamic among adolescents, parents and providers.

BACKGROUND: With several new vaccine recommendations specifically targeting adolescents, improving adolescent vaccination rates has become a major health priority. Vaccination attitudes are an important, modifiable target for new interventions. Prior research has examined primarily the attitudes and beliefs of adolescents, parents or healthcare providers separately without exploring the decision-making dynamic among these stakeholders. We sought to identify potentially modifiable barriers in the vaccine decision process among adolescents, parents and healthcare providers that could be addressed through interventions implemented within the adolescent's medical home. METHODS: We conducted a qualitative study of adolescents, their parents and healthcare providers, recruited from four primary care practices in Michigan. For each practice, three separate focus group discussions (adolescents, parents and healthcare providers, for a total of 12 focus groups) were conducted to explore vaccination attitudes, possible interventions to improve vaccine uptake and access to and use of technology for vaccination interventions. Themes that emerged from the focus group discussions were categorized using an inductive, iterative process, and analysis focused on highlighting similarities and differences among the three perspectives. RESULTS: Participants included 32 adolescents, 33 parents and 28 providers. The majority of parents and adolescents were female. Lack of knowledge about recommended adolescent vaccinations was universally recognized among the three groups and was perceived to be the underlying driver of low immunization rates. Notably, each group did not appear to fully appreciate the challenges faced by the other stakeholders with respect to adolescent vaccination. Adolescents were seen as having a greater role in the vaccine decision-making dynamic than previously suggested. Provider-based interventions such as educational tools and reminder-recall notices were identified as important components of any immunization program. Overall, there was high receptivity among all stakeholders toward integrating technology such as email and Internet into new vaccination interventions. CONCLUSIONS: We identified potentially modifiable attitudinal barriers to adolescent vaccination among the three key stakeholders. However, there were notable differences in attitudes and preferences across the three perspectives, indicating that for an intervention to be successful it will require a dynamic partnership with the target audiences.

Identifying children with chronic conditions for influenza vaccination using a statewide immunization registry: initial experiences of primary care providers.

CONTEXT: Children with chronic medical conditions are at increased risk of complications from influenza, yet their vaccination rates are low. The Michigan Care Improvement Registry (MCIR), a statewide immunization registry, was expanded in 2006 to include an indicator, based on Medicaid administrative claims, that prompts providers to offer influenza vaccine to high-risk children (ie, those with chronic conditions). OBJECTIVE: To assess primary care providers' experiences with the MCIR high-risk indicator. DESIGN: A cross-sectional, self-administered survey mailed in July 2009. SETTING: State of Michigan. PARTICIPANTS: A total of 300 family physicians and 300 pediatricians who served as primary care providers for children in Michigan's Medicaid program. MAIN OUTCOME MEASURES: Provider experiences with the high-risk indicator; suggestions for improvement. RESULTS: Response rate was 79%. Only 32% of pediatricians and 17% of family physicians recalled seeing the high-risk indicator during the 2008-2009 influenza season. Of those who saw the indicator, 48% rated it as "helpful" or "very helpful" in identifying which children should receive flu vaccine. To improve its usefulness, 77% of respondents wanted the indicator to reflect all children, rather than only those enrolled in Medicaid, and 71% wanted MCIR to generate a list of high-risk children in their practice. CONCLUSIONS: Three years after implementation, the registry-based high-risk indicator is not viewed by most providers. Half of those who saw the indicator found it helpful, and most respondents endorsed enhancements to broaden its scope. Future work should explore whether enhanced capabilities help to facilitate identification of priority cases by providers.

Using Medicaid claims to identify children with asthma.

OBJECTIVE: To assess the accuracy of using administrative data from state-managed programs to identify children with asthma in a statewide immunization information system. We wished to understand the degree to which alternative asthma case definitions applied to administrative data influence the accuracy of cases identified in an immunization information system. DESIGN & SETTING: Children aged 2 to 18 years were sequentially classified into 3-case definition groups on the basis of Michigan Department of Community Health administrative data (2005-2006): (1) children with a Children's Special Health Care Services (CSHCS) Program qualifying diagnosis of asthma (CSHCS cases); (2) those having 1 or more asthma medication claims (Rx cases); or (3) those without asthma medications having 1 or more health services claim reporting an asthma diagnosis code (Dx cases). PARTICIPANTS: Children were randomly selected from each asthma case definition group; parents were invited to participate in a telephone interview to document physician diagnosis of asthma, symptoms, activity limitations, medications, and asthma health services use. MAIN OUTCOME MEASURES: The positive predictive value of parent report of a physician diagnosis of asthma; asthma severity, based on National Asthma Education and Prevention Program criteria. RESULTS: : Of 440 completed interviews, 89% of parents confirmed the child's high-risk status, reporting physician diagnosis of asthma (83%), wheezy-cough (5%), or reactive airway disease (1%). The positive predictive value varied for CSHCS cases (100%), Rx cases (91%) and Dx cases (73%, P < .0001). Although reported asthma severity levels were similar among CSHCS and Rx cases (P = .9100), asthma severity was lower among Dx cases (P = .0218). CONCLUSIONS: Medicaid administrative data can be used to accurately identify children with asthma and represents a feasible approach for Medicaid programs and health plans to identify priority groups for targeted influenza vaccination reminders.

Considerations When Aggregating Data to Measure Performance Across Levels of the Health Care System.

BACKGROUND: Measuring quality at varying levels of the health care system requires attribution, a process of determining the patients and services for which each level is responsible. However, it is important to ensure that attribution approaches are equitable; otherwise, individuals may be assigned differentially based upon social determinants of health. METHODS: First, we used Medicaid claims (2010-2018) from Michigan to assess the proportion of children with sickle cell anemia who had less than 12 months enrollment within a single Medicaid health plan and could therefore not be attributed to a specific health plan. Second, we used the Medicaid Analytic eXtract data (2008-2009) from 26 states to simulate adapting the 30-Day Pediatric All-Condition Readmission measure to the Accountable Care Organization (ACO) level and examined the proportion of readmissions that could not be attributed. RESULTS: For the sickle cell measure, an average of 300 children with sickle cell anemia were enrolled in Michigan Medicaid each year. The proportion of children that could not be attributed to a Medicaid health plan ranged from 12.2% to 89.0% across years. For the readmissions measure, of the 1,051,365 index admissions, 22% were excluded in the ACO-level analysis because of being unable to attribute the patient to a health plan for the 30 days post discharge. CONCLUSIONS: When applying attribution models, it is essential to consider the potential to induce health disparities. Differential attribution may have unintentional consequences that deepen health disparities, particularly when considering incentive programs for health plans to improve the quality of care.