Richard M. Fairbanks School of Public Health Theses and Dissertations

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Understanding the Influence of State Policy Environment on Dental Service Availability, Access, and Oral Health in America's Underserved Communities
(2014) Maxey, Hannah L.; Wright, Eric; Halverson, Paul K.; Williams, John N.; Liu, Ziyue
Oral health is crucial to overall health and a focus of the U.S. Health Center program, which provides preventive dental services in medically underserved communities. Dental hygiene is an oral health profession whose practice is focused on dental disease prevention and oral health promotion. Variations in the practice and regulation of dental hygiene has been demonstrated to influence access to dental care at a state level; restrictive policies are associated lower rates of access to care. Understanding whether and to what extent policy variations affect availability and access to dental care and the oral health of medically underserved communities served by grantees of the U.S. Health Center program is the focus of this study. This longitudinal study examines dental service utilization at 1,135 health center grantees that received community health center funding from 2004 to 2011. The Dental Hygiene Professional Practice Index (DHPPI) was used as an indicator of the state policy environment. The influence of grantee and state level characteristics are also considered. Mixed effects models were used to account for correlations introduced by the multiple hierarchical structure of the data. Key findings of this study demonstrate that state policy environment is a predictor of the availability and access to dental care and the oral health status of medically underserved communities that received care at a grantee of the U.S. Health Center program. Grantees located in states with highly restrictive policy environments were 73% less likely to deliver dental services and, those that do, provided care to 7% fewer patients than those grantees located in states with the most supportive policy environments. Population’s served by grantees from the most restrictive states received less preventive care and had greater restorative and emergency dental care needs. State policy environment is a predictor of availability and access to dental care and the oral health status of medically underserved communities. This study has important implications for policy at the federal, state, and local levels. Findings demonstrate the need for policy and advocacy efforts at all levels, especially within states with restrictive policy environments.
Dietary intake and urinary excretion of phytoestrogens in relation to cancer and cardiovascular disease
(2014) Reger, Michael Kent; Zollinger, Terrell; Jones, Josette F.; Liu, Ziyue; Zhang, Jianjun
Phytoestrogens that abound in soy products, legumes, and chickpeas can induce biologic responses in animals and humans due to structural similarity to 17β-estradiol. Although experimental studies suggest that phytoestrogen intake may alter the risk of cancer and cardiovascular disease, few epidemiologic studies have investigated this research question. This dissertation investigated the associations of intake of total and individual phytoestrogens and their urinary biomarkers with these chronic conditions using data previously collected from two US national cohort studies (NHANES and PLCO). Utilizing NHANES data with urinary phytoestrogen concentrations and follow-up mortality, Cox proportional hazards regression (HR; 95% CI) were performed to evaluate the association between total cancer, cardiovascular disease, and all-cause mortality and urinary phytoestrogens. After adjustment for confounders, it was found that higher concentrations of lignans were associated with a reduced risk of death from cardiovascular disease (0.48; 0.24-0.97), whereas higher concentrations of isoflavones (2.14; 1.03-4.47) and daidzein (2.05; 1.02-4.11) were associated with an increased risk. A reduction in all-cause mortality was observed for elevated concentrations of lignans (0.65; 0.43-0.96) and enterolactone (0.65; 0.44-0.97). Utilizing PLCO data and dietary phytoestrogens, Cox proportional hazards regression examined the associations between dietary phytoestrogens and the risk of prostate cancer incidence. After adjustment for confounders, a positive association was found between dietary intake of isoflavones (1.58; 1.11-2.24), genistein (1.42; 1.02-1.98), daidzein (1.62; 1.13-2.32), and glycitein (1.53; 1.09-2.15) and the risk of advanced prostate cancer. Conversely, an inverse association existed between dietary intake of genistein and the risk of non-advanced prostate cancer (0.88; 0.78-0.99) and total prostate cancer (0.90; 0.81-1.00). C-reactive protein (CRP) concentration levels rise in response to inflammation and higher levels are a risk factor for some cancers and cardiovascular disease reported in epidemiologic studies. Logistic regression performed on NHANES data evaluated the association between CRP and urinary phytoestrogen concentrations. Higher concentrations of total and individual phytoestrogens were associated with lower concentrations of CRP. In summary, dietary intake of some phytoestrogens significantly modulates prostate cancer risk and cardiovascular disease mortality. It is possible that these associations may be in part mediated through the influence of phytoestrogen intake on circulating levels of C-reactive protein.
Role of patients’ perception of barriers to taking medication on medication adherence among patients with diabetes: development and psychometric evaluation of the murage-marrero-monahan medication barriers scale (4m scale), patient characteristics associated with medication barriers, and association of medication barriers and cardiovascular disease (CVD) risk
(2014) Murage, Mwangi James; Swanson, G. Marie; Marrero, David G.; Wessel, Jennifer
Medication adherence remains a problem among Type-2 diabetes (T2D) patients despite availability of effective treatments. Three analyses of extant data sets were conducted to examine barriers to using medication as prescribed as an alternate method to assess medication adherence: 1) development and psychometric evaluation of the Murage-Marrero-Monahan-Medication barriers (4M) scale to assess patients’ perceived barriers; 2) patient demographic factors associated with barriers to using medication as prescribed, and 3) the association between patients’ perceived barriers to medication use and cardiovascular disease (CVD) risk factor control.Twelve focus groups and a cross-sectional study of 362 T2D patients contributed to develop and evaluate psychometric properties of the 4M scale. A cross-sectional survey of 964 T2D patients was used for the other two studies. Analysis of covariance identified demographic factors associated with reported barriers. Multivariable logistic regression was used to identify barriers associated with CVD risk factors (glucose, blood pressure and lipids) categorized as either poor or good control. Exploratory factor analysis with Varimax rotation resulted in a 19-item 4M scale with acceptable psychometric properties. As a five-domain (or single-domain) structure, coefficient alpha ranged from 0.70 to 0.83 (0.92). Both structures demonstrated discriminant validity and known-group validity. Age was inversely associated with all identified barriers while income was inversely associated with poor communication with providers and side effects. A unit increase in the overall barrier mean score on the 4M scale was associated with 92% increase in the odds of having poor control of two or more CVD risk factors compared to good control of all three risk factors (adjusted OR=1.92, 95% CI: 1.16–3.17; p<0.05). The 4M scale demonstrated acceptable psychometric properties in assessing barriers to using medication among T2D patients. Poor medication adherence has been previously associated with CVD risk. In this study, greater barriers were associated with poorer control of CVD risk factors making barriers a potential alternative to medication adherence, whose current assessment methods are limited. The 4M scale has the advantage to identify specific barriers inhibiting medication use that can facilitate patient-provider discussions and the development of targeted interventions.
The legal and ethical implications of the Indiana surrogate decision making impact on physicians and patient care in Indiana hospitals
(2015) Comer, Amber R.; Silverman, Ross David; Torke, Alexia Mary; Eberl, Jason; Gaffney, Margaret M.; Stone, Cynthia L.
Background: When a patient is incapacitated and unable to make health care decisions, a surrogate decision maker must be designated to make decisions about the patient’s care in his or her place. Studies show that fewer than 20% of patients in hospitals present with a designated health care representative form. Therefore, the overwhelming majority of surrogates in hospitals are identified via default state statutes. Little is known about the implications of state default surrogate decision making statutes on physicians and patient care in clinical practice. Methods: An evaluation of state surrogate decision making statutes was conducted in order to determine variability among state laws. Additionally, a statewide, quantitative, descriptive, cross-sectional survey of a random sample of 405 physicians working in Indiana hospitals was conducted to determine: 1) physicians’ knowledge of Indiana’s surrogate decision making law; 2) physicians’ approaches to hypothetical cases they might encounter in hospital practice; and 3) any delay in patient care physicians experience as a result of state surrogate decision making laws. Results: There is very little consistency among states regarding who may serve as a surrogate decision maker. In Indiana, less than half of the surveyed physicians (47.90%) were able to correctly identify legally allowable surrogates. When presented with clinica vignettes, nearly all physicians (84.90%) report that they would allow a grandchild to act as a surrogate decision maker, even though grandchildren are not legal surrogates under the law. Additionally, more than half of physicians (53.8%) experienced a delay in patient care due to the inability to identify a legal surrogate. Conclusions: The narrow construction of state laws can leave patients in situations where they either have no qualified surrogate under the law or where they have multiple surrogates. If there are multiple surrogates with competing interests a consensus may not be reached on the patient’s medical care. These situations result in a delay of patient care. The results of this study show that the Indiana Surrogate Decision Making law is flawed as it does not reflect the composition of Indiana families and leads to delays in patient care.
Obesity and obesity-related markers associated with breast and colorectal cancer occurence and mortality
(2016-04-05) Gathirua-Mwangi, Wambui Grace; Zollinger, Terrell W.; Song, Yiqing; Champion, Victoria L.; Monahan, Patrick O.
Purpose: Obesity is a growing public health problem and the second most preventable cause of death in the US. Obesity has been linked as a risk factor for several cancers. However, there are limited studies that have examined the roles of metabolic syndrome (MetS) and C-reactive protein (CRP), as well as change in body composition from early adulthood to late adulthood on the risk of cancer. The overall objective of this dissertation was to determine the association of obesity and obesity-related markers with breast and colorectal cancer occurrence and mortality. Methods: Three datasets were used. The first study used 4,500 asymptomatic adults who were surveyed during a colorectal cancer screening study. The second study was based on the National Health and Nutrition Examination Survey (NHANES) 2005-2010. The dataset had 172 breast cancer survivors and 2,000 women without breast cancer. The last manuscript resulted from the NHANES follow-up study (NHANES III). A total of 120 cancer deaths from breast and colorectal deaths were identified from 10,103 women aged 18 years or older. Results: Overall, obesity and obesity related markers were associated with breast and colorectal cancer occurrence and mortality. BMI change and WC change were positively associated with increased risk of advanced colorectal neoplasia (AN). WC measures (both static and dynamic) were generally a better predictor of AN compared to BMI. In the second study involving breast cancer survivors, neither MetS nor CRP were associated with having a breast cancer diagnosis. Also, none of the individual components of MetS (WC, Triglycerides, HDL, fasting blood glucose and blood pressure) were associated with a breast cancer diagnosis. In the last study, MetS was associated with increased risk of mortality from obesity-related cancers. In addition, all components of MetS, except dyslipidemia, were associated with increased risk of mortality for the obesity-related cancers. Conclusion: Obesity expressed in terms of BMI and WC, or their change, MetS and CRP are important factors in regard to the occurrence, survivorship and mortality of breast and colorectal cancer. The results of this research underscore the importance of maintaining a healthy weight.
Human papillomavirus vaccination status association with subsequent health behaviors
(2016-04-28) Kasting, Monica Louise; Zimet, Gregory D.
Human papillomavirus (HPV) infection results in serious health issues including cervical, anal, vulvar, penile and oropharyngeal cancers. There are three vaccines against HPV but vaccination rates in the United States remain low. One barrier to uptake is a concern that individuals who are vaccinated may increase their risky sexual behaviors or decrease their use of cervical cancer screenings, an adjustment in perceived level of risk for HPV that can be studied using risk compensation theory. Methods Three distinct studies examined risk compensation after HPV vaccination. A systematic review examined literature from January 1, 2008-June 30, 2015, using three databases. A qualitative study using semi-structured interviews of 22 healthcare providers that assessed their beliefs regarding sexual disinhibition and cervical cancer screening following vaccination. A cross-sectional survey that assessed cervical cancer screening practices, awareness and comfort with recommendations, and knowledge regarding the purpose of a Papanicolaou (Pap) test. Results Twenty articles were included in the systematic review. None of the studies of sexual behaviors and/or biological outcomes found evidence of riskier behaviors after HPV vaccination. Instead, the studies found vaccinated individuals were less likely to report risky sexual behaviors, sexually transmitted infections (STIs), and pregnancy. Qualitative interviews found no healthcare providers believed the HPV vaccine would result in increased risky sexual behavior or decreased cervical cancer screening, and these concerns would not influence their vaccination recommendations. The survey included 291 women 21-35 years old; 62% were non-Hispanic black, 84% had a Pap test in the last three years, and 33% had at least one HPV vaccine. Logistic regression showed that vaccinated women did not have greater odds of having a Pap test in the past three years (OR=1.32; 95% CI=0.66-2.65; p=0.427). However, this odds ratio was significant when controlling for age and race (AOR=3.06; 95% CI=1.37-6.83; p=0.006). Conclusion These studies found no evidence of increased risky sexual behaviors or decreased cervical cancer screening rates after HPV vaccination. Furthermore, vaccinated women showed less evidence of risk compensation. These results should alleviate concerns about administering the HPV vaccination among parents and providers.
Living kidney donor follow-up in a statewide health information exchange: health services utilization, health outcomes and policy implications
(2016-05-24) Henderson, Macey Leigh; Stone, Cynthia L.; Dixon, Brian; Harle, Chris; Menachemi, Nir; Holmes, Ann; Fry-Revere, Sigrid
Living donors have contributed about 6,000 kidneys per year in the past 10 years, but more than 100,000 individuals are still waiting for a kidney transplant. Living kidney donors undergo a major surgical procedure without direct medical benefit to themselves, but comprehensive follow-up information on living donors’ health is unfortunately limited. Expert recommendations suggest capturing clinical information beyond traditional sources to improve surveillance of co-morbid conditions from living kidney donors. Currently the United Network for Organ Sharing is responsible for collecting and reporting follow-up data for all living donors from U.S. transplant centers. Under policy implemented in February of 2013, transplant centers must submit follow-up date for two years after donation, but current processes often yield to incomplete and untimely reporting. This dissertation uses a statewide Health Information Exchange as a new clinical data source to 1) retrospectively identify a cohort of living kidney donors, 2) understand their follow-up care patterns, and 3) observe selected clinical outcomes including hypertension, diabetes and post-donation renal function.
A longitudinal analysis for the identification of the factors that affect the case mix index of hospitals in the U.S
(2017-05) Chasioti, Danai; Yiannoutsos, Constantin T.
The present thesis is an analysis of longitudinal data collected through the years 2011-2013, from a complex of four hospitals located in Indiana, USA. The aim of the analysis was the detection of changes (especially a decline) in the disease related group (DRG) weights (and thus, the case mix index (CMI)), and the determination of the predictors that significantly affect these changes. The document is divided in four major parts. In the first part it is described the statistical theory required for the the analysis, in the second part the reimbursement strategies for the hospitals in the USA, are briefly described and the concept of the DRG and CMI are explained. In the third part the actual analysis is presented while the last part contains a summary of the findings and some conclusions. The correlation between the observations was taken into account by modeling the data using linearmixed models (LMM). Three major factors were studied for their effect on the DRG weight of thehospitals: the changes in the type of cases (i.e. the product lines), the changes in the number of the Surgical cases, and also the changes of the length of stay (LOS). The analysis did not indicate any significant DRG change in any of the hospitals except from the H4. The H4 hospital has a significant decline over time regarding the Cardio-vascular (CV) DRG weights. For the hospitals H1, H2 and H3 the only decline observed in the product lines was that for the Medical-Surgical DRG. Finally, no significant change was observed for the LOS, or the number of Surgical cases. In addition to the three predictors studied, changes in the coding system, the documentation etc. may also affect the DRG and CMI. However, these changes are not possible to be detected through this analysis, since no available information was given in the present data.
Nurse practitioner patient care patterns and practice characteristics : understanding the role of state scope-of-practice policies
(2017-05-09) Norwood, Connor W.; Harle, Christopher; Menachemi, Nir; Stone, Cynthia; Liu, Ziyue
Introduction: The U.S. is faced with a primary care (PC) workforce shortage; an estimated 43 percent of the population has unmet health care needs and 18.2 percent of the adult population lacks a usual source of care (USC) provider. The workforce shortage limits even those with a USC from receiving the full scope of recommended clinical services. One promising solution is reforming scope-of-practice (SOP) policies for PC nurse practitioners (NPs). Objectives: The primary objective of this dissertation was to assess the impact of NP SOP policy implementation on NP practice patterns and patient access to PC by evaluating NP time spent delivering patient care, NP role as USC providers, patient travel times, and appointment availability. Methods: The studies discussed in this dissertation leveraged cross-sectional data from the National Sample Survey of Nurse Practitioners (NSSNP), time-series data from the Medical Expenditure Panel Survey (MEPS), and the Nurse Practitioner Professional Practice Index (NPPPI) to quantify variations in state policy environments. We used generalized mixed effects models to examine relationships in the cross-sectional data analyses and two-way fixed effect models to evaluate longitudinal data. Results: Our analyses revealed several key findings: NP SOP policies do impact the percentage of time NPs spend providing direct patient care; the NP workforce role as USC providers has increased as SOP policies have changed; states with supportive reimbursement policies have more NPs working as USC providers; and states with fewer NP supervision requirements have shorter patient travel times to USC providers. Conclusion: The U.S. health care system must continue to evolve to address the growing demand for PC services. While strategies to increase the supply of PC providers may be an effective long-term solution, our findings suggest that NP SOP reform may be a viable and complementary strategy to increasing the capacity of the PC workforce, providing more immediate relief.
Associations between traits (blood pressure and body height growth) and reproductive timing related genetic variants from genome-wide association studies
(2017-07-18) Mo, Daojun; He, Chunyan; Tu, Wanzhu; Song, Yiqing; Stone, Cynthia S.
Recent genome-wide association studies (GWAS) have identified many common genetic variants that are associated with women’s reproductive timing characteristics including ages at menarche and at natural menopause. However, the associations of these variants with other human health related phenotypes such as blood pressure, cancer, diabetes, obesity, and body height growth have not been well studied. No published studies to our knowledge have directly assessed the genetic influence of reproductive timing related variants on the aforementioned common traits. A better understanding of pleiotropic effects of these variants is important because it will help elucidate the precise mechanisms of common traits/diseases such as hypertension which have not been fully understood so far, and give clues for developing better solutions for disease prevention and treatment. We, therefore, conducted three studies to explore genetic variant effects on blood pressure and body height growth. In the first study, we analyzed data from a local cohort of 601 healthy adolescents from Indianapolis schools. Mixed effect model analysis revealed that 11 reproductive related single nucleotide polymorphisms (SNPs) were significantly associated with blood pressure in the study subjects. In order to assess if these genetic effects extended to the adult blood pressure, we performed the second study to investigate the genetic effect on blood pressure in adults. We used the summary statistics obtained from the two large international GWAS consortia, the Blood Pressure Consortium and the ReproGen Consortium. Bivariate analyses showed that more than 100 SNPs were associated with both blood pressure and reproductive timing. As the blood pressure development is closely related to somatic growth, we conducted the third study to exam the genetic effect of reproductive-timing related variants on the linear growth from the aforementioned local cohort. We identified 8 genetic variants significantly associated with the catch-up of linear growth in the study subjects. In conclusion, these three studies collectively provided evidence in support of the pleiotropic effects of the reproductive timing variants, suggesting the common genetic basis underlying the correlated traits. Future research is needed to validate the findings.

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