Browsing by Author "Tu, Wanzhu"
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Item A Consideration of Genetic Mechanisms Behind the Development of Hypertension in Blacks(Springer, 2013) Tu, Wanzhu; Pratt, J. Howard; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public HealthHypertension is a more serious disease in blacks. The determinants of the blood pressure (BP) may be uniquely different from those in whites. The characteristic low-renin, salt-sensitive hypertension of blacks is consistent with the kidney reabsorbing additional sodium (Na), which leads to an expanded plasma volume that drives the BP. Mechanisms considered are genetically based. These include: (1) the intra-renal renin-angiotensin system (RAS), one based on molecular variations in angiotensinogen; (2) the Na, K, 2Cl cotransporter (NKCC2) and its regulators in the thick ascending limb, which are associated with a variety of phenotypes consistent with a more active cotransporter in blacks; and (3) the genes for MYH9 and APOL 1, which have been associated with kidney disease in blacks. To achieve a state of hypertension, an increase in Na uptake in proximal nephron regions may require a distal nephron that does not fully adjust due to less than adequate suppression of aldosterone production.Item A Contextual Approach to the Psychological Study of Identity Concealment: Examining Direct, Interactive, and Indirect Effects of Structural Stigma on Concealment Motivation Across Proximal and Distal Geographic Levels(Sage, 2021) Lattanner, Micah R.; Ford, Jessie; Bo, Na; Tu, Wanzhu; Pachankis, John E.; Dodge, Brian; Hatzenbuehler, Mark L.; Biostatistics, School of Public HealthPsychological theories of identity concealment locate the ultimate source of concealment decisions within the social environment, yet most studies have not explicitly assessed stigmatizing environments beyond the immediate situation. We advanced the identity-concealment literature by objectively measuring structural forms of stigma related to sexual orientation (e.g., social policies) at proximal and distal geographic levels. We linked these measures to a new, population-based data set of 502 gay and bisexual men (residing in 44 states and Washington, DC; 269 counties; and 354 cities) who completed survey items about stigma, including identity-concealment motivation. Among gay men, the association between structural stigma and concealment motivation was (a) observed across three levels (city, county, and state), (b) conditional on one's exposure at another geographic level (participants reported the least motivations to conceal their identity if they resided in both cities and states that were lowest in structural stigma), and (c) mediated by subjective perceptions of greater structural stigma.Item A matched analysis of the use of high flow nasal cannula for pediatric severe acute asthma(Wiley, 2024) Rogerson, Colin; AbuSultaneh, Samer; Sanchez‐Pinto, L. Nelson; Gaston, Benjamin; Wiehe, Sarah; Schleyer, Titus; Tu, Wanzhu; Mendonca, Eneida; Pediatrics, School of MedicineRationale: The high-flow nasal cannula (HFNC) device is commonly used to treat pediatric severe acute asthma. However, there is little evidence regarding its effectiveness in real-world practice. Objectives: We sought to compare the physiologic effects and clinical outcomes for children treated for severe acute asthma with HFNC versus matched controls. Methods: This was a single-center retrospective matched cohort study at a quaternary care children's hospital. Children ages 2-18 hospitalized for severe acute asthma from 2015 to 2022 were included. Encounters receiving treatment with HFNC within the first 24 h of hospitalization were included as cases. Controls were primarily treated with oxygen facemask. Logistic regression 1:1 propensity score matching was done using demographics, initial vital signs, and medications. The primary outcome was an improvement in clinical asthma symptoms in the first 24 h of hospitalization measured as percent change from initial. Measurements and main results: Of 693 eligible cases, 443 were matched to eligible controls. Propensity scores were closely aligned between the cohorts, with the only significant difference in clinical characteristics being a higher percentage of patients of Black race in the control group (54.3% vs. 46.6%; p = 0.02). Compared to the matched controls, the HFNC cohort had smaller improvements in heart rate (-11.5% [-20.9; -0.9] vs. -14.7% [-22.6;-5.7]; p < 0.01), respiratory rate (-14.3% [-27.9;5.4] vs. -16.7% [-31.5;0.0]; p = 0.03), and pediatric asthma severity score (-14.3% [-28.6;0.0] vs. -20.0% [-33.3;0.0]; p < 0.01) after 24 h of hospitalization. The HFNC cohort also had longer pediatric intensive care unit (PICU) length of stay (LOS) (1.5 days [1.1;2.1] vs. 1.2 days [0.9;1.8]; p < 0.01) and hospital LOS (2.8 days [2.1;3.8] vs. 2.5 days [1.9;3.4]; p < 0.01). When subgrouping to younger patients (2-3 years old), or those with the highest severity scores (PASS > 9), those treated with HFNC had no difference in clinical symptom improvements but maintained a longer PICU LOS. Conclusions: Encounters using HFNC for severe acute pediatric asthma had decreased clinical improvement in 24 h of hospitalization compared to matched controls and increased LOS. Specific subgroups of younger patients and those with the highest severity scores showed no differences in clinical symptom improvement suggesting differential effects in specific patient populations.Item A reference-free R-learner for treatment recommendation(Sage, 2023) Zhou, Junyi; Zhang, Ying; Tu, Wanzhu; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public HealthAssigning optimal treatments to individual patients based on their characteristics is the ultimate goal of precision medicine. Deriving evidence-based recommendations from observational data while considering the causal treatment effects and patient heterogeneity is a challenging task, especially in situations of multiple treatment options. Herein, we propose a reference-free R-learner based on a simplex algorithm for treatment recommendation. We showed through extensive simulation that the proposed method produced accurate recommendations that corresponded to optimal treatment outcomes, regardless of the reference group. We used the method to analyze data from the Systolic Blood Pressure Intervention Trial (SPRINT) and achieved recommendations consistent with the current clinical guidelines.Item Addressing People and Place Microenvironments in Weight Loss Disparities (APP-Me): Design of a randomized controlled trial testing timely messages for weight loss behavior in low income black and white women(Elsevier, 2018) Clark, Daniel O.; Srinivas, Preethi; Bodke, Kunal; Keith, NiCole; Hood, Sula; Tu, Wanzhu; Medicine, School of MedicineBackground Behavioral interventions for weight loss have been less effective in lower income and black women. These poorer outcomes may in part be related to these women having more frequent exposures to social and physical situations that are obesogenic, i.e., eating and sedentary cues or situations. Objectives Working with obese, lower income black and white women, Addressing People and Place Microenvironments (APP-Me) was designed to create awareness of self-behavior at times and places of frequent eating and sedentary behavior. Design APP-Me is being evaluated in a randomized controlled trial with 240 participants recruited from federally qualified health centers located in a single Midwestern city. All participants complete four weeks of ecological momentary assessments (EMA) of situations and behavior. At the end of the four weeks, participants are randomized to enhanced usual care (UC) or UC plus APPMe. Methods APP-Me is an automated short messaging system (SMS). Messages are text, image, audio, or a combination, and are delivered to participants’ mobile devices with the intent of creating awareness at the times and places of frequent eating or sedentary behavior. The EMA data inform the timing of message deliveries. Summary This project aims to create and test timely awareness messages in a subpopulation that has not responded well to traditional behavioral interventions for weight loss. Novel aspects of the study include the involvement of a low income population, the use of data on time and place of obesogenic behavior, and message delivery time tailored to an individual’s behavioral patterns.Item Adiposity has unique influence on the renin-aldosterone axis and blood pressure in black children(Elsevier, 2013-11) Yu, Zhangsheng; Eckert, George; Liu, Hai; Pratt, J. Howard; Tu, Wanzhu; Medicine, School of MedicineOBJECTIVE: To comparatively examine the effects of adiposity on the levels of plasma renin activity (PRA), plasma aldosterone concentration (PAC), and aldosterone-renin ratio (ARR) in young black and white children. STUDY DESIGN: We prospectively assessed 248 black and 345 white children and adolescents. A novel analytical technique was used to assess the concurrent influences of age and body mass index (BMI) on PRA, PAC, and ARR. The estimated effects were depicted by colored contour plots. RESULTS: In contrast to whites, blacks had lower PRA (2.76 vs 3.36 ng/mL/h; P < .001) and lower PAC (9.01 vs 14.59 ng/dL; P < .001). In blacks, BMI was negatively associated with PRA (P = .001), consistent with an association with a more expanded plasma volume; there was no association with PAC. In whites, BMI was positively associated with PAC (P = .005); we did not detect a BMI-PRA association. The effects of BMI on ARR were directionally similar in the two race groups but more pronounced in blacks. Mean systolic blood pressure was greater in blacks with lower PRA (P < .01), higher PAC (P = .015), and higher ARR (P = .49). CONCLUSIONS: An increase in adiposity was associated with a suppressed PRA in blacks and an increase in PAC in whites. The unique relationship between adiposity and renin-aldosterone axis in blacks suggests the possible existence of a population-specific mechanism characterized by volume expansion, which could in turn enhance the influences of adiposity on blood pressure in black children and adolescents.Item Age Differences in the Association Between Body Mass Index Class and Annualized Medicare Expenditures(SAGE, 2016-02) Clark, Daniel O.; Lane, Kathleen A.; Ambuehl, Roberta; Tu, Wanzhu; Liu, Chiung-Ju; Unroe, Kathleen; Callahan, Christopher M.; Department of Medicine, IU School of MedicineOBJECTIVE: The aim of the study is to assess the relationship between body mass index (BMI) class and Medicare claims among young-old (65-69), old (70-74), and old-old (75+) adults over a 10-year period. METHOD: We assessed costs by BMI class and age group among 9,300 respondents to the 1998 Health and Retirement Study (HRS) with linked 1998-2008 Medicare claims data. BMI was classified as normal (18.5-24.9), overweight (25-29.9), mild obesity (30-34.9), or severe obesity (35 or above). RESULTS: Annualized total Medicare claims adjusted for age, gender, ethnicity, education, and smoking history were 109% greater for severely obese young-old adults in comparison with normal weight young-old adults (US$9,751 vs. US$4,663). Total annualized claim differences between the normal weight and severely obese in the old and old-old groups were not statistically significant. DISCUSSION: Excess Medicare expenditures related to obesity may be concentrated among severely obese young-old adults. Preventing severe obesity among middle and older aged adults may have large cost implications for society.Item Age-specific rates of hospital transfers in long-stay nursing home residents(Oxford Academic, 2022-01) Tu, Wanzhu; Li, Ruohong; Stump, Timothy E.; Fowler, Nicole R.; Carnahan, Jennifer L.; Blackburn, Justin; Sachs, Greg A.; Hickman, Susan E.; Unroe, Kathleen T.; Biostatistics, School of Public HealthIntroduction hospital transfers and admissions are critical events in the care of nursing home residents. We sought to determine hospital transfer rates at different ages. Methods a cohort of 1,187 long-stay nursing home residents who had participated in a Centers for Medicare and Medicaid demonstration project. We analysed the number of hospital transfers of the study participants recorded by the Minimum Data Set. Using a modern regression technique, we depicted the annual rate of hospital transfers as a smooth function of age. Results transfer rates declined with age in a nonlinear fashion. Rates were the highest among residents younger than 60 years of age (1.30-2.15 transfers per year), relatively stable between 60 and 80 (1.17-1.30 transfers per year) and lower in those older than 80 (0.77-1.17 transfers per year). Factors associated with increased risk of transfers included prior diagnoses of hip fracture (annual incidence rate ratio or IRR: 2.057, 95% confidence interval (CI): [1.240, 3.412]), dialysis (IRR: 1.717, 95% CI: [1.313, 2.246]), urinary tract infection (IRR: 1.755, 95% CI: [1.361, 2.264]), pneumonia (IRR: 1.501, 95% CI: [1.072, 2.104]), daily pain (IRR: 1.297, 95% CI: [1.055,1.594]), anaemia (IRR: 1.229, 95% CI [1.068, 1.414]) and chronic obstructive pulmonary disease (IRR: 1.168, 95% CI: [1.010,1.352]). Transfer rates were lower in residents who had orders reflecting preferences for comfort care (IRR: 0.79, 95% CI: [0.665, 0.936]). Discussion younger nursing home residents may require specialised interventions to reduce hospital transfers; declining transfer rates with the oldest age groups may reflect preferences for comfort-focused care.Item Aldosterone sensitivity: an opportunity to explore the pathogenesis of hypertension(American Physiological Society, 2021-03) Gray, Zachary; Tu, Wanzhu; Chertow, Glenn M.; Bhalla, Vivek; Biostatistics, School of Public HealthAldosterone sensitivity is defined as an outcome variable for a given circulating level of aldosterone. In basic and translational studies, aldosterone sensitivity has been measured in differential tissue responses, e.g., lower urine sodium and higher urine potassium, as an index of the renal response; in clinical studies, aldosterone sensitivity has been measured in differential blood pressure responses. The concept of aldosterone sensitivity disrupts the conventional wisdom of the renin-angiotensin-aldosterone system and has the potential to uncover novel mechanisms of hypertension. Here, we review basic and translational science studies that uncovered differential renal responses to aldosterone and connect this earlier work to more recent observational studies and randomized trials that have demonstrated differential blood pressure responses for a given level of aldosterone in healthy and hypertensive persons. Black race and older age are associated with higher aldosterone sensitivity and blood pressure. We also discuss gaps in the field and how future basic and clinical studies might inform mechanisms of differential sensitivity.Item Anxiety but not Social Stressors Predict 12-Month Depression and Pain Severity(Wolters Kluwer, 2013) Bair, Matthew J.; Poleshuck, Ellen L.; Wu, Jingwei; Krebs, Erin K.; Damush, Teresa M.; Tu, Wanzhu; Kroenke, Kurt; Medicine, School of MedicineObjectives: To determine whether baseline anxiety and social stressors as well their early change (first 3 months) predict 12-month depression and pain severity. Methods: We analyzed data from the Stepped Care for Affective Disorders and Musculoskeletal Pain study, a randomized clinical trial of a combined medication-behavioral intervention for primary care patients with chronic musculoskeletal pain and depression. Using multivariable linear regression modeling, we examined the independent association of baseline anxiety and social stressors with depression and pain severity at 12 months. In addition, we modeled whether changes in anxiety and social stressors predicted 12-month depression and pain severity. Results: Overall, the sample (N=250) was 52.8% women with a mean age of 55.5 years, and a racial distribution of 60.4% white, 36.4% black, and 3.2% other. Depression and pain were moderately severe at baseline (mean SCL-20 depression=1.9 and Brief Pain Inventory pain severity=6.15) and similar across intervention and usual care arms. Baseline anxiety symptoms predicted both depression (t score=2.13, P=0.034) and pain severity (t score=2.75, P=0.007) at 12 months. Also, early change in anxiety predicted 12-month depression (t score=-2.47, P=0.014), but not pain. Neither baseline nor early change in social stressors predicted depression or pain severity. Conclusions: Anxiety, but not social stressors predict 12-month depression and pain severity. The presence of comorbid anxiety should be considered in the assessment and treatment of patients with musculoskeletal pain and depression, particularly as a factor that may adversely affect treatment response.