Browsing by Author "Wang, Yumin"
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Item Dental safety net capacity: An innovative use of existing data to measure dentists’ clinical engagement in state Medicaid programs(Wiley, 2018) Maxey, Hannah L.; Norwood, Connor W.; Vaughn, Sierra X.; Wang, Yumin; Marsh, Stacie; Williams, John; Family Medicine, School of MedicineBackground The demand for dentists available for state Medicaid populations has long outpaced the supply of such providers. To help understand the workforce dynamics, this study sought to develop a novel approach to measuring dentists’ relative contribution to the dental safety net and, using this new measurement, identify demographic and practice characteristics predictive of dentists’ willingness to participate in Indiana's Medicaid program. Methods We examined Medicaid claims data for 1,023 Indiana dentists. We fit generalized ordered logistic regression models to measure dentists’ level of clinical engagement with Medicaid. Using a partial proportional odds specification model, we estimated proportional adjusted odds ratios for covariates and separate estimates for each contrast of nonproportional covariates. Results Though 75% of Medicaid‐enrolled dentists were active providers, only 27% of them had 800 or more claims during fiscal year 2015. As has been shown in previous studies, our findings from the proportional odds model reinforced certain demographic and practice characteristics to be predictive of dentists’ participation in state Medicaid programs. Conclusions In addition to confirming predictive factors for Medicaid enrollment, this study validated the clinical engagement measure as a reliable method to assess the level of Medicaid participation. Prior studies have been limited by self‐reported data and variations in Medicaid claims reporting.Item Fasting C-peptide values among adolescents in the National Health and Nutrition Examination Surveys(Wiley, 2022-03) Soni, Priya Y.; Wang, Yumin; Eckert, George J.; Ismail, Heba M.; Pediatrics, School of MedicineAim To report fasting C-peptide values and variations across demographics in healthy non-diabetic adolescents included in the National Health and Nutrition Examination Surveys (NHANES) dataset. Research Design and Methods In this analysis, we used fasting C-peptide data from the 1999 to 2004 NHANES dataset for participants aged 12 to <18 years (n = 2063). Results The mean ± SE age of the participants was 14.99 ± 0.06 years. The participants included 992 girls and 1071 boys, and more than 80% of participants had a body mass index (BMI) percentile of <85%. Among boys, the most notable finding was the increase in geometric mean C-peptide level from 0.51 nmol/L at age 12, to 0.65 nmol/L at age 15 years. Among girls, levels fluctuated around a geometric mean of 0.67 nmol/L. Girls had significantly higher mean log-transformed C-peptide concentrations than boys (P < 0.0001) after adjusting for age, race and BMI percentile category. After adjusting for age and BMI percentile category, non-Hispanic Black boys and girls had significantly lower C-peptide levels than non-Hispanic White (P = 0.0026 and P = 0.0093) and Mexican American boys and girls (P < 0.0001 and P < 0.0001), respectively. Despite these findings, both insulin and homeostatic model assessment of insulin resistance were greater in non-Hispanic Black compared to non-Hispanic White participants. Conclusions Here we describe fasting C-peptide levels in a non-diabetic adolescent population. These data provide crucial insight into evaluating racial differences in endogenous insulin release and clearance and will provide novel information which can be used in assessing residual β-cell function and response to intervention therapy.Item High Polygenic Risk Scores Are Associated With Early Age of Onset of Alcohol Use Disorder in Adolescents and Young Adults at Risk(Elsevier, 2022-10) Nurnberger, John I., Jr.; Wang, Yumin; Zang, Yong; Lai, Dongbing; Wetherill, Leah; Edenberg, Howard J.; Aliev, Fazil; Plawecki, Martin H.; Chorlian, David; Chan, Grace; Bucholz, Kathleen; Bauer, Lance; Kamarajan, Chella; Salvatore, Jessica E.; Kapoor, Manav; Hesselbrock, Victor; Dick, Danielle; Bierut, Laura; McCutcheon, Vivia; Meyers, Jacquelyn L.; Porjesz, Bernice; Kramer, John; Kuperman, Samuel; Kinreich, Sivan; Anokhin, Andrey P.; Collaborative Study on the Genetics of Alcoholism; Psychiatry, School of MedicineBackground Genome-wide association studies have been conducted in alcohol use disorder (AUD), and they permit the use of polygenic risk scores (PRSs), in combination with clinical variables, to predict the onset of AUD in vulnerable populations. Methods A total of 2794 adolescent/young adult subjects from the Collaborative Study on the Genetics of Alcoholism were followed, with clinical assessments every 2 years. Subjects were genotyped using a genome-wide chip. Separate PRS analyses were performed for subjects of European ancestry and African ancestry. Age of onset of DSM-5 AUD was evaluated using the Cox proportional hazard model. Predictive power was assessed using receiver operating characteristic curves and by analysis of the distribution of PRS. Results European ancestry subjects with higher than median PRSs were at greater risk for onset of AUD than subjects with lower than median PRSs (p = 3 × 10–7). Area under the curve for the receiver operating characteristic analysis peaked at 0.88 to 0.95 using PRS plus sex, family history, comorbid disorders, age at first drink, and peer drinking; predictive power was primarily driven by clinical variables. In this high-risk sample, European ancestry subjects with a PRS score in the highest quartile showed a 72% risk for developing AUD and a 35% risk of developing severe AUD (compared with risks of 54% and 16%, respectively, in the lowest quartile). Conclusions Predictive power for PRSs in the extremes of the distribution suggests that these may have future clinical utility. Uncertainties in interpretation at the individual level still preclude current application.Item Longitudinal assessment of Indiana dentists’ participation in Medicaid before and after expansion(Elsevier, 2022-07) Maxey, Hannah L.; Vaughn, Sierra X.; Medlock, Courtney R.; Dickinson, Analise; Wang, Yumin; Family Medicine, School of MedicineBackground Although Medicaid expansion aims to eliminate financial barriers to health care for low-income people in the United States, health care accessibility cannot be guaranteed without clinicians who provide health care to Medicaid recipients. This study examined the characteristics of Indiana dentists that are associated with the likelihood of participating in Medicaid after expansion in 2015. Methods This study included Indiana-licensed dentists who renewed their licenses in 2018 and provided supplemental data elements related to demographics, education and training, and professional characteristics. Dentists’ Medicaid engagement behavior was categorized on the basis of when claims were submitted from 2014 through 2017. Statistical analyses included the χ2 test and generalized multinomial logit model. Results Overall, 2,037 Indiana-licensed dentists were included in the study. Of these, 802 (39.4%) were continually active in Medicaid during the study period, and 116 (5.7%) became active after expansion. Dentists had a greater likelihood of engaging in Medicaid after expansion if they were female, specialized in oral and maxillofacial surgery, practiced in a group practice, and were located in a rural county. Conclusions This study shows that dentists with certain demographic and practice characteristics had a greater likelihood of participation in Indiana Medicaid after expansion in 2015. Several findings from this study are consistent with previous research regarding the emerging trends in workforce diversity and show the impact of expansion policies on the dental safety net. Practical Implications This study presents an effective framework for the use of administrative and regulatory data sources for state-level analysis of the Medicaid safety net.Item Removal of medicaid restrictions were associated with increased hepatitis C virus treatment rates, but disparities persist(Wiley, 2022) Nephew, Lauren D.; Wang, Yumin; Mohamed, Kawthar; Nichols, Deborah; Rawl, Susan M.; Orman, Eric; Desai, Archita P.; Patidar, Kavish R.; Ghabril, Marwan; Chalasani, Naga; Kasting, Monica L.; Medicine, School of MedicineDespite the release of a growing number of direct-acting antivirals and evolving policy landscape, many of those diagnosed with hepatitis C virus (HCV) have not received treatment. Those from vulnerable populations are at particular risk of being unable to access treatment, threatening World Health Organization (WHO) HCV elimination goals. The aim of this study was to understand the association between direct-acting antivirals approvals, HCV-related policy changes and access to HCV virus treatment in Indiana, and to explore access to treatment by race, birth cohort and insurance type. We performed a retrospective cohort study of adults with HCV from 05/2011-03/2021, using statewide electronic health data. Nine policy and treatment changes were defined a priori. A Lowess curve evaluated treatment trends over time. Monthly screening and treatment rates were examined. Multivariable logistic regression explored predictors of treatment. The population (N = 10,336) was 13.4% Black, 51.8% was born after 1965 and 44.7% was Medicaid recipients. Inflections in the Lowess curve defined four periods: (1) Interferon + DAA, (2) early direct-acting antivirals, (3) Medicaid expansion/optimization and (4) Medicaid restrictions (fibrosis/prescriber) removed. The largest increase in monthly treatment rates was during period 4, when Medicaid prescriber and fibrosis restrictions were removed (2.4 persons per month [PPM] in period 1 to 72.3 PPM in period 4, p < 0.001; 78.0% change in slope). Multivariable logistic regression analysis showed being born after 1965 (vs. before 1945; OR 0.69; 95% 0.49-0.98) and having Medicaid (vs. private insurance; OR 0.47; 95% CI 0.42-0.53), but not race was associated with lower odds of being treated. In conclusion, DAAs had limited impact on HCV treatment rates until Medicaid restrictions were removed. Additional policies may be needed to address HCV treatment-related age and insurance disparities.Item Scratching the Surface of Psychiatric Services Distribution and Public Health: an Indiana Assessment(Springer, 2018) Moberly, Steven; Maxey, Hannah; Foy, Lacy; Vaughn, Sierra X.; Wang, Yumin; Diaz, David; Family Medicine, School of MedicineMental illness is a leading cause of disability with many public health implications. Previous studies have demonstrated a national shortage of psychiatrists, particularly in rural areas. An analysis of how this workforce distribution relates to population demographics and public/behavioral health is lacking in the literature. This study encompassed a statewide assessment of the Indiana psychiatric workforce as it relates to population characteristics and public/behavioral health. This study’s findings demonstrate a profoundly low psychiatry workforce in rural counties of Indiana. The low psychiatry workforce capacity in rural counties is so disparate that the demographic and public/behavioral health characteristics differ from the State averages in the same manner as counties without a psychiatrist at all. The psychiatric workforce distribution did not differ significantly on the basis of poverty prevalence. The potential utility of indicators of population health was also evaluated and revealed that social factors such as poverty and Medicaid prevalence may be superior to more traditional measures.Item T3 + 3: 3 + 3 Design With Delayed Outcomes(Wiley, 2024) Guo, Jiaying; Lu, Mengyi; Wan, Isabella; Wang, Yumin; Han, Leng; Zang, Yong; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public HealthDelayed outcome is common in phase I oncology clinical trials. It causes logistic difficulty, wastes resources, and prolongs the trial duration. This article investigates this issue and proposes the time-to-event 3 + 3 (T3 + 3) design, which utilizes the actual follow-up time for at-risk patients with pending toxicity outcomes. The T3 + 3 design allows continuous accrual without unnecessary trial suspension and is costless and implementable with pretabulated dose decision rules. Besides, the T3 + 3 design uses the isotonic regression to estimate the toxicity rates across dose levels and therefore can accommodate for any targeted toxicity rate for maximum tolerated dose (MTD). It dramatically facilitates the trial preparation and conduct without intensive computation and statistical consultation. The extension to other algorithm-based phase I dose-finding designs (e.g., i3 + 3 design) is also studied. Comprehensive computer simulation studies are conducted to investigate the performance of the T3 + 3 design under various dose-toxicity scenarios. The results confirm that the T3 + 3 design substantially shortens the trial duration compared with the conventional 3 + 3 design and yields much higher accuracy in MTD identification than the rolling six design. In summary, the T3 + 3 design addresses the delayed outcome issue while keeping the desirable features of the 3 + 3 design, such as simplicity, transparency, and costless implementation. It has great potential to accelerate early-phase drug development.