School of Public Health
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
Note: Prior to July 1, 2007, the School of Public Health was named the College of Health & Human Performance.
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Item ALLOSTATIC LOAD INFLUENCES VASCULAR FUNCTION AND SYMPATHOLYSIS IN YOUNG BLACK ADULTS(2024) Eagan, Lauren Elizabeth; Ranadive, Sushant M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the U.S., Black individuals tend to face a disproportionately higher risk for hypertension. This is largely attributed to chronic sympathetic activation induced by heightened exposure to psychosocial stressors. Allostatic load (AL), an index of cumulative physiological dysfunction from chronic stress, is associated with hypertensive risk and is also heightened in Black adults compared to those of other racial groups. Indeed, increased sympathetic activity is a hallmark characteristic of both hypertension and AL. The inability to blunt sympathetic-induced vasoconstriction during exercise (impaired functional sympatholysis) is also associated with hypertension. This dissertation aimed to investigate whether AL was associated with measures of vascular health in young Black adults, both at rest and during a sympathetic stressor. In our first study, we examined associations between AL and indices of vascular function and structure among young Black adults at rest, finding that higher AL was associated with greater macrovascular dysfunction and amplified wave-reflections. Additionally, we identified significant correlations among greater self-perceived stress with smaller brachial artery diameters and greater wave-reflections. The second aim of this dissertation focused on the associations between AL and the magnitude of functional sympatholysis among this population. Results indicated a positive association between AL and functional sympatholysis, with amplified sympatholytic responses among young Black females, as compared to their male counterparts, when forearm volume was controlled for. Overall, our findings suggest that elevated AL might predict macrovascular dysfunction at rest, with larger arterial diameters potentially compensating for chronic stress. These adaptive mechanisms, commonly observed in aging and diseased states, may also explain the positive correlations between AL and the functional sympatholytic response in young Black adults. Our consistent observations of the redundant vascular mechanisms among young Black adults allowing for adaptation to chronic stress strengthen our findings and further highlight the complex interplay between stress and cardiovascular health in Black adults.Item LGBTQ+ Youth Therapeutic Engagement and Experiences: Associations with LGBTQ+ Family Environment(2024) Zheng, Azure; Fish, Jessica N,; Family Studies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)LGBTQ+ youth experience unique stressors that increase the risk for poor mental health. LGBTQ+ youth’s family environment, often measured as parental acceptance and rejection of youth’s LGBTQ+ status, is associated with youth mental health; less often studied is how the family environment may be linked to LGBTQ+ youth’s access to therapy and, more importantly, experiences with LGBTQ+ affirmative and competent providers. Using a contemporary non-probability national sample of LGBTQ+ youth ages 13-17, our study examined the association among LGBTQ+ youth’s reports of caregiver supportive and rejection behaviors related to their LGBTQ+ identity and youth’s engagement and experiences in therapy. Using a step-wise logistic regression method, results tell a clear story. There is a consistent positive association between parent’s LGBTQ+ support behaviors and (1) youth access to therapy and (2) their therapists' LGBTQ+ competency. In the absence of controls, we found that parents’ rejecting behaviors were also positively associated with the youth’s access to therapy, but this relationship was mediated by the youth’s depression and anxiety symptoms. For youth who did not access therapy in the last year, those who reported more parental support were inversely related, and parental rejection positively related to wanting therapy but not receiving it. Youth who reported more rejecting behaviors from parents were less likely to perceive their therapists as LGBTQ+ competent. Findings point to varied pathways and experiences in therapy engagement for LGBTQ+ youth based on parents' support of their LGBTQ+ identity.Item LOWER LIMB ASYMMETRY AND LOADING IN INDIVIDUALS WITH UNILATERAL TRANSFEMORAL AMPUTATIONS WITH A LIFETIME OF OSSEOINTEGRATED PROSTHESIS USE(2023) Burnett, Jenna K; Shim, Jae Kun; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Individuals with transfemoral amputation commonly develop chronic health problems due to decreased physical activity as a result of the missing musculature and tissue on the amputated side, and the poor imitation of the intact limb provided by the prosthesis. In addition, the indirect and semi-rigid connection of the socket to the body may increase interlimb asymmetries, as well as lead to pain and discomfort on the residual limb. Recent innovations have introduced a bone-anchored or osseointegrated (OI) implant which connects the prosthesis to the skeleton, and removes most of the socket related pain and discomfort complaints, as well as providing a rigid connection which may reduce the interlimb asymmetries. However, the direct bone and prosthesis connection may also introduce longitudinal bone health concerns due to the repetitive loads during walking. This dissertation investigated the effect of walking speed on the loads placed on the lower limbs of 11 individuals who use an OI prosthesis at 3 different anatomical levels, including the whole limb through interlimb ground reaction force, the joints through interlimb joint kinematics and kinetics, and finally the residual limb bone through implant input forces, finite element analysis of bone strain, and the probability of bone injury with a simulated lifetime of use.In study 1, the interlimb ground reaction force asymmetries were found to be moderate to large at all walking speeds, and to have a general increase as individuals walked faster, indicating there is an intact limb reliance strategy which may be used to compensate for the limitations of the amputated limb. Similarly, in study 2, the interlimb joint kinematics and kinetics were found to have moderate to large asymmetries at each joint level, with a general increase in asymmetry at faster walking, with this increase largely due to limitations within the prothesis. In study 3, the abutment force decreased in magnitude with walking speed, but the peak strain on the bone, and the probability of injury was greater for the preferred speed and fast speed walking when compared to slow speed walking. However, the overall probability of injury was low for all speeds, indicating the ability of the bone to repair and adapt with sustained loading likely provides effective protection over a lifetime of simulated OI prothesis use. The findings of this dissertation suggest that the more rigid connection afforded by the OI implant cannot fully remove the interlimb asymmetries which occur as a result of the poor imitation of the intact limb provided by the prosthesis and prosthesis components, but that there is minimal risk to the bone due to a lifetime of sustained walking with an OI prosthesis as a result the inherent ability of the bone to repair and adapt to variable loads over time. Therefore, while an OI prosthesis may not fully mitigate the interlimb asymmetries which occur as a result of the prosthesis limitations, individuals who use an OI prosthesis may feel confident that there is minimal longitudinal risk to the bone as a result of walking over their lifetime.Item Home Hemodialysis Utilization and Health Outcomes among Racial and Ethnic Minority Populations(2023) Zhu, Ying; Franzini, Luisa; Health Services Administration; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Home hemodialysis (HHD) offers end-stage renal disease (ESRD) patients greater flexibility and advantages in terms of health outcomes over in-center hemodialysis. There is limited research on the differences between home and center hemodialysis (CHD) and preferences among racial/ethnic minorities, despite ESRD disproportionately affecting these groups. Methods: This project aims to explore the usage and health outcomes of HHD vs. CHD with a focus on racial/ethnic differences using a systematic review of the global main academic database from 2004 to 2022 (study 1), logistic regression and negative binomial analysis of the U.S. Renal Disease System (USRDS) cumulative core data since 2010 merged with 2016-2019 Medicare clinical claims (study 2), and qualitative research using semi-structured interviews with 18 nephrologists and 5 other hemodialysis providers in 8 states of the U.S. (study 3). Results: Study 1: from 3,114 unique studies, six studies met the inclusion criteria and all of them were comparative cohort studies; five out of six studies with a total of 3,172 White patients (68%) and 1,477 minority patients (32%) reported the utilization of HHD; in four of the six studies, the adjusted odds ratio for HHD treatment was shown to be significantly lower for patients of racial or ethnic minorities than for White patients; three out of six studies examined racial/ethnic differences in mortality and other outcomes indicating a lower risk of death for minorities in home hemodialysis. Study 2: minorities were significantly less likely to use HHD than Whites; most minority patients were younger and had fewer comorbidities than Whites, and all minority groups displayed significantly lower mortality and hospitalization incidences than the White group with adjustment on multiple covariates; in the overall and main racial/ethnic cohorts, HHD showed a significantly lower risk of death than CHD after confounding for major risk factors. Study 3: the majority of the interviewees felt that HHD was a viable, safe, and most cost-effective treatment for those with kidney failure, it offered many advantages over traditional CHD but there is a need for additional training and support for the patient, family, provider; minorities and White patients differed in their attitude toward dialysis care, social norms on HHD, and perceived control of personal health. Conclusion: There were major obstacles and considerable racial/ethnic variations in HHD utilization and health outcomes in the US. This study showed that the promotion of HHD will probably require a systematic overhaul in kidney disease management and education.Item A Qualitative Examination of the Barriers and Facilitators of Pre-Exposure Prophylaxis (PrEP) Uptake Among Heterosexual HIV Serodiscordant Couples(2022) Mathews, Ronneal; Mittal, Mona; Family Studies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)It is estimated that there are 140,000 heterosexual serodiscordant couples in the United States. Given the considerable number of these couples and the high risk of HIV acquisition among non-infected partners, it is important to focus prevention methods on programs and interventions that target transmission of HIV infection among serodiscordant heterosexual couples. Currently, we understand little about factors that influence these couples to use pre-exposure prophylaxis (PrEP). According to the CDC, this population is one of the highest risk groups, therefore, understanding the factors that influence them to use PrEP as a strategy in their HIV prevention regimen is an important step in preventing new HIV cases among this population. This study was a qualitative analysis that explored potential motivators and inhibitors for PrEP among heterosexual HIV serodiscordant couples. Secondary data from 26 qualitative interviews of HIV serodiscordant couples (N = 52 individuals) was examined to determine the factors that influenced the decision to use PrEP. Overall, there were five overarching themes from the Health Belief Model that manifested in all participant interviews. Perceived threat, perceived barriers (concerns about side effects, fear/anxiety about taking medication, indifference about HIV transmission), perceived benefits, cues to action (partner protection, PrEP use as condom replacement, PrEP use due to concerns about condom efficacy), and relational efficacy emerged as the most salient themes that determined whether couples chose to use PrEP as an HIV prevention method. Two constructs from the Theory of Gender and Power, sexual division of power and cathexis also emerged as relevant factors that influenced the decision to use PrEP in these couples. Findings from this study indicate that practitioners need to consider the motivators and barriers to PrEP uptake, and critically examine how power dynamics impact the decision to use PrEP. There is a need for the development of couples-based interventions to encourage PrEP uptake and adherence in mixed status couples.Item Novel Immunotherapy Agents in Oncology: Generalizability of Trial Results and Drivers of Clinical Utilization(2021) Mishkin, Grace; Franzini, Luisa; Health Services Administration; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cancer is the second most common cause of death in the United States after heart disease. Novel immunotherapy agents such as nivolumab and pembrolizumab have become an essential, albeit extremely expensive, component of oncology care since their first approvals in melanoma in 2014 and lung cancer in 2015. However, little is known about differences between immunotherapy clinical trial participants and the real-world patient population, or about the drivers of provider utilization of these agents. The first objective of this dissertation used the SEER-Medicare linked database with claims data from 2014-2016 to conduct two aims analyzing potential disparities between Medicare beneficiaries on active treatment for melanoma and lung cancer and Medicare clinical trial participants. Aim one compared the characteristics of Medicare patients on active cancer treatment to Medicare patients on active cancer treatment clinical trials. Aim two compared Medicare patients receiving the novel immunotherapy agents nivolumab or pembrolizumab to Medicare patients participating in trials of these two immunotherapy agents. Because of the demographic differences in the melanoma and lung cancer patient populations, these aims were analyzed separately in melanoma and lung cancer. As hypothesized, patients in clinical trials were significantly younger and had fewer comorbid conditions than patients undergoing active cancer treatment not in clinical trials. Underrepresentation of non-White and female patients in clinical trials was hypothesized, but these results were less consistent. The second objective used Medicare Open Payments data from 2016 and Medicare provider utilization data from 2017 to analyze 1) if industry payments promoting nivolumab or pembrolizumab were positively associated with whether a provider was a high utilizer of the agent, and 2) among these high utilizers, if industry payments were positively associated with greater utilization amounts. The hypothesized results, that industry payments were associated with greater likelihood of high utilization and more utilization among high utilizers, were seen in some of the analyses but not consistently throughout the study. Through unique analyses of recent datasets, this dissertation advances our understanding of potential disparities in clinical trial representativeness and the generally positive relationship between promotional payments and provider utilization of immunotherapy agents in the Medicare cancer patient population.Item Perceived Discrimination and Multimorbidity Among Middle-Aged and Older Adults(2020) Howard, Jianna; White, Kellee; Health Services Administration; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Multimorbidity, the presence of multiple chronic conditions, is increasingly recognized by researchers as a major health priority. Relative to younger adults, the burden is much higher among middle-aged and older adults with prevalence estimates ranging from 25-98%. Variations in the burden of multimorbidity within the aging population exist with a growing body of research showing racial/ethnic differences in the incidence, prevalence, and severity of multimorbidity. This study analyzed the association between perceived racial discrimination and multimorbidity among middle-aged and older adults and whether or not existing associations vary by race/ethnicity. Findings show that individuals reporting perceived discrimination are more likely to have multimorbidity. While racial/ethnic differences in the association between perceived discrimination and multimorbidity were not observed, Black respondents displayed the greatest risk for multimorbidity. Perceived discrimination may provide insight into why multimorbidity varies by race/ethnicity through the mechanisms of stress responses and health behaviors.Item RACIAL DIFFERENCES IN VASCULAR FUNCTION FOLLOWING INDUCED ACUTE INFLAMMATION(2020) Chesney, Catalina Anne; Ranadive, Sushant M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)African-Americans (AAs) have higher rates of cardiovascular disease (CVD), including hypertension and stroke, as compared to their Caucasian-American (CA) counterparts. High resting concentrations of systemic inflammatory biomarkers contribute to vascular dysfunction and are predictive of future cardiovascular events; differential resting levels of inflammatory markers between groups may reveal increased potential for CVD in at-risk groups. Additionally, impaired endothelial function and increased arterial stiffness, subclinical measures of CVD progression, have been reported in AA groups. The purpose of this study was to examine race differences between young, healthy AA and CA adults after a systemic inflammatory stimulus and subsequent endothelial responses to inflammation. Endothelial function, arterial stiffness, and hemodynamic variables were measured. The results suggest there were no race differences in vascular function or hemodynamic responses following an acute inflammatory stimulus.Item THE IMPACT OF DISEASE SEVERITY AND PHENOTYPE ON SMOKING AMONG ADULTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE(2019) Tilert, Timothy; Wang, Min Q; Public and Community Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Chronic Obstructive Pulmonary Disease (COPD) is estimated to be the third leading cause of death in the US. The most significant risk factor for COPD is long-term cigarette smoking. In spite of the myriad benefits of cessation, the proportion of adults with COPD who currently smoke is still nearly 50%. Little is known, however, about the characteristics of, and subsequent differences between, smokers with COPD, particularly at differing lung obstruction severity levels. The goals of this dissertation were to examine and compare the characteristics of smokers with diagnosed COPD as well as to explore the impact of disease severity and disease phenotype on smoking status among persons with COPD. This research utilized secondary data on 10,219 examined adults, aged 40-79 years, from the 2007-2012 National Health and Nutrition Examination Survey. In Study 1, adjusted logistic regression analyses revealed multiple factors that were associated with self-reported COPD diagnosis with those reporting three or more respiratory symptoms having the strongest association (AOR=22.1, 95% CI=12.0-40.5). In Study 2, it was shown that smoking status proportions did not differ by lung obstruction severity among those reporting a COPD diagnosis. In adjusted logistic regression analyses, multiple factors were associated with current smoking status among those with self-reported COPD with the presence of other smokers in the household having the strongest association with being a current smoker (AOR=19.5, 95% CI=10.2-37.5). In Study 3, three distinct phenotypes were found among the COPD population analyzed. In adjusted logistic regression analyses, COPD phenotype was differentially associated with continued smoking, above and beyond other predictors, with the older, heavy-smoking males with emphysema phenotype showing a significant positive association with continued smoking (AOR=3.7, 95% CI=1.3-10.9). Understanding how differences in disease severity and disease phenotypes impact smoking status among persons with diagnosed COPD could help inform more targeted, and effective, interventions to reduce smoking rates in this high-risk population. These findings potentially provide guidance for current smoking cessation interventions aimed at smokers with COPD as well as provide the foundation for further exploration of the association between COPD phenotype and continued smoking.Item Understanding and Retraining the Causal Attributions for Exercise Intenders(2019) Singpurwalla, Darius; Iso-Ahola, Seppo E; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Given that ~50% of all exercise intenders will fall into the intention-behavior gap (i.e., a situation where people fail to act on their intentions), it is necessary to identify the constructs and/or theories that can explain the discord between intention and behavior (i.e., the intention-behavior gap). For this purpose, the present research was conducted through two studies that were designed to test the efficacy of causal attributions as a means to reduce the intention-behavior discord. The first study collected information from 952 individuals on their exercise behavior and their associated causal attributions over a six-week period. The findings from this study included: (1) those individuals who fell into the intention-behavior gap made self-serving attributions for their exercise failure; (2) Weiner’s model accurately predicted several of the affective and cognitive responses to exercise behavior for the sample of exercise intenders; and (3) causal attributions were not found to be effective moderators of the intention-behavior relationship. The second study was an experiment that tested whether an attribution retraining intervention could improve exercise behavior for a sample of sedentary, exercise intenders (n=200). Results of this study were mixed as the intervention appeared to have been able to modify one of the targeted attributional dimensions (control), but the effect was not strong enough to change the exercise behavior of the participants in the experimental group. It is suggested that attributions may not be able to reduce the gap because they represent conscious deliberations of the behavior, while sustained exercise is based on nonconscious processing of relevant information to make exercise an automatic behavior.