Epidemiology & Biostatistics

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Acculturation and BMI among Chinese, Korean and Vietnamese Adults in Maryland
(2011) Chen, Lu; Lee, Sunmin; Carter-Pokras, Olivia D; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Objective: To examine the relationship between acculturation and BMI among Asian Americans. Methods: Data of 847 Chinese, Korean and Vietnamese recruited for a health education program in Maryland were included. Acculturation was measured by the short version of Suinn-Lew Asian Self-Identity Acculturation Scale (SL-ASIA) and its individual components. Height and weight were measured by trained staff. Multiple linear regression was used to estimate the parameters of acculturation variables. Results: After adjusting for confounders, SL-ASIA (β=0.71, 95% CI: 0.15, 1.26), having education in the U.S (β=0.56, 95% CI: 0.01, 1.11), younger age of arrival (0-5 years: β=3.32, 95% CI: 1.84, 4.80, 6-10 years: β=1.55, 95% CI: 0.02, 3.07) and equal preference of Asian/American food in restaurants (β=0.92, 95% CI 0.38, 1.46) were associated with BMI. The association between acculturation and BMI was stronger among men than women, and weakest among Vietnamese. Conclusion: Acculturation is moderately associated with BMI among Asian Americans.
Allostatic load amplifies the effect of blood lead levels on elevated blood pressure among middle-aged U.S. adults: a cross-sectional study
(Springer Nature, 2013-08-16) Zota, Ami R; Shenassa, Edmond D; Morello-Frosch, Rachel
Scientists and regulators have sought to understand whether and how physiologic dysregulation due to chronic stress exposure may enhance vulnerability to the adverse health effects of toxicant exposures. We conducted a cross-sectional study to determine whether allostatic load (AL), a composite measure of physiologic response to chronic exposure to stress, amplifies the effect of lead exposure on blood pressure among middle-aged adults. We analyzed associations between blood lead levels and blood pressure in a nationally representative sample of 8,194 U.S. adults (aged 40-65 years) participating in the National Health and Nutritional Examination Survey, 1999--2008. Outcomes were elevated systolic (≥ 140 mm Hg) and diastolic (≥ 90 mm Hg) blood pressure. AL was defined as the aggregate score of seven components, reflecting dysregulation of the cardiovascular, inflammatory, and endocrine systems. Logistic regression models showed a linear dose-response relationship for quintiles of blood lead and elevated systolic blood pressure in the high AL group (p = 0.03) but not the low AL group (p = 0.24). Similarly, the relationship between lead exposure and elevated diastolic blood pressure was stronger among the high AL group than the low AL group. Within the high AL group, the fourth and fifth quintiles had significantly elevated odds of elevated blood pressure compared to lowest quintile [OR = 1.92, (95% CI, 1.07, 3.47) and OR =2.28 (95% CI, 1.33, 3.91), respectively]. In the low AL group, none of the quintile effects were significantly different than the referent group although there was evidence of a linear trend (p =0.03). The lead by AL interaction term was not statistically significant for either systolic or diastolic blood pressure models. Results suggest that higher AL may amplify the adverse effects of lead on blood pressure. Future research should assess the implications of cumulative exposures to environmental and social stressors for regulatory decision-making.
Analysis of Factors Associated With Tuberculosis Outcomes in District Kullu, India
(2012) Stone, Heather; Lee, Sunmin; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
India is the country with the largest number of tuberculosis (TB) cases, contributing 20% of the global burden of infection (1) and 2 million cases annually (2). However, few if any studies have examined the epidemiology of TB in the Northern state of Himachal Pradesh. This study is a retrospective review of medical records of all tuberculosis patients (N=1086) seen at the two hospitals in Manali, District Kullu, Himachal Pradesh, India between 2008-2011. The analysis determined that being younger, female, living in a town, and/or a patient at Mission Hospital, were factors significantly associated with having extrapulmonary versus pulmonary tuberculosis (EPTB). Being older was associated with an increased likelihood of previous/complex treatment compared to new patients. Being female, from a town, and/or older were associated with receiving a non-standard regimen. Finally, patients who were previously treated/complex were significantly more likely to receive a non-standard regimen than new patients.
APPLIED EPIDEMIOLOGICAL STUDIES OF HIGH RISK HUMAN PAPILLOMAVIRUS INFECTIONS AND RISK OF CERVICAL PRECANCER
(2017) Demarco, Maria Teresa; Carter-Pokras, Olivia; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Persistent infection with human papillomavirus (HPV) is a leading cause of cancer among women worldwide. Health care providers face a growing number of competing cervical cancer screening approaches and tests. HPV testing is very sensitive but a secondary test is needed to identify infections with sufficient risk of cervical precancer/cancer. This dissertation aims to address three questions in the management of HPV infections: (1) to compare the first HPV screening test seeking FDA approval that identifies many individual HPV types (BD Onclarity™) to two FDA approved assays (Roche cobas™ and Qiagen HC2™); (2) to clarify how HPV type influences cumulative risk of clearance, progression or persistence of HPV infections; and (3) to assess whether established etiologic co-factors for cervical precancer, given HPV infection, represent clinically useful, actionable factors that clinicians “need to know” when considering how to manage the HPV infected woman. All manuscripts in this dissertation used data from the HPV Persistence and Progression Cohort, conducted by Kaiser Permanente Northern California and the National Cancer Institute. The study population is a group of 33,295 women, ages 30 or older, who are HPV positive at baseline and have results for cytology. Contingency table methods, Kappa statistics and McNemar’s test were used to assess agreement between HPV DNA tests (manuscript 1). Competing risk proportional hazards models were used to estimate eight-year cumulative risks of HPV clearance, progression to precancer, or persistence (manuscript 2). Absolute risks from Logistic-Cox models were used to study whether co-factors acted as clinically relevant risk stratifiers (manuscript 3). Results from this dissertation suggest that: (1) Onclarity agreement was good to excellent compared with cobas and HC2, and clinical accuracy was high for detection of precancer; (2) cumulative risk of clearance varied little by HPV type, cumulative risk of progression was substantially higher for HPV16, and long-term persistence was uncommon; and (3) the most important predictors of progression from HPV infection to precancer were HPV type and cytologic result. By clarifying these aspects of methods, and management of HPV-positive women, it is hoped that this dissertation will contribute to the improvement of cervical cancer screening incorporating HPV testing.
Assessing Health Concerns and Barriers in a Heterogeneous Latino Community
(The Johns Hopkins University Press, 2006) Martinez, Iveris L.; Carter-Pokras, Olivia
Introduction. Major health issues and barriers to health services for Latino immigrants were identified through community-based participatory research in Baltimore city. Methods. In collaboration with community partners, five focus groups were conducted among Latino adults from 10 countries and health service providers. Findings. Priorities across groups included chronic diseases, HIV/AIDS and STDs, mental health, and the need for ancillary services. Community members and providers did not always agree on what health matters were of primary concern. Participants expected to receive health information at the point of service. Barriers to receiving health services and information span linguistic, financial, logistical, legal, and cultural matters. Conclusions. This formative research illustrates the complexity and interrelatedness of health priorities and barriers created by social issues such as employment, legal status, and related stressors.
Association between Allostatic Load and Arthritis in NHANES Adults
(2010) Scully, Lynn; Lee, Sunmin; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Objective: To examine the cross-sectional association between allostatic load and arthritis using data from the National Health and Nutrition Examination Survey (NHANES). Methods: Complete data on 7,714 adults were included in the analysis. An allostatic load (AL) index, comprising of multiple regulatory systems, was calculated from 11 biomarkers. Multivariate logistic regression was used to estimate the odds ratio (OR) for the association between allostatic load and arthritis, while accounting for confounders. Results: Significant positive associations were found between both continuous allostatic load (OR=1.12, 95% CI= 1.08-1.17) and the two highest quartile categories of AL and arthritis compared to the lowest quartile (quartile 3: OR=1.73, 95% CI=1.38-2.17, quartile 4: OR=1.79, 95% CI=1.41-2.26), after adjusting for confounders. The subscales of the inflammatory (OR=1.27, 95% CI=1.15-1.40) and metabolic system (OR=1.20, 95% CI=1.13-1.28) were also significant predictors. Conclusions: Cumulative biological risk is a plausible mechanism that is associated with arthritis.
Association between an Internet-Based Measure of Area Racism and Black Mortality
(PLOS (Public Library of Science), 2015-04-24) Chae, David H.; Clouston, Sean; Hatzenbuehler, Mark L.; Kramer, Michael R.; Cooper, Hannah L. F.; Wilson, Sacoby M.; Stephens-Davidowitz, Seth I.; Gold, Robert S.; Link, Bruce G.
Racial disparities in health are well-documented and represent a significant public health concern in the US. Racism-related factors contribute to poorer health and higher mortality rates among Blacks compared to other racial groups. However, methods to measure racism and monitor its associations with health at the population-level have remained elusive. In this study, we investigated the utility of a previously developed Internet search-based proxy of area racism as a predictor of Black mortality rates. Area racism was the proportion of Google searches containing the “N-word” in 196 designated market areas (DMAs). Negative binomial regression models were specified taking into account individual age, sex, year of death, and Census region and adjusted to the 2000 US standard population to examine the association between area racism and Black mortality rates, which were derived from death certificates and mid-year population counts collated by the National Center for Health Statistics (2004–2009). DMAs characterized by a one standard deviation greater level of area racism were associated with an 8.2% increase in the all-cause Black mortality rate, equivalent to over 30,000 deaths annually. The magnitude of this effect was attenuated to 5.7% after adjustment for DMA-level demographic and Black socioeconomic covariates. A model controlling for the White mortality rate was used to further adjust for unmeasured confounders that influence mortality overall in a geographic area, and to examine Black-White disparities in the mortality rate. Area racism remained significantly associated with the all-cause Black mortality rate (mortality rate ratio = 1.036; 95% confidence interval = 1.015, 1.057; p = 0.001). Models further examining cause-specific Black mortality rates revealed significant associations with heart disease, cancer, and stroke. These findings are congruent with studies documenting the deleterious impact of racism on health among Blacks. Our study contributes to evidence that racism shapes patterns in mortality and generates racial disparities in health.
Association Between C-Reactive Protein and Serum 25-Hydroxyvitamin D: A Negative Acute Phase Reactant
(2015) Verdin, Kelly; Lee, Sunmin; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Objective: The aims of this study were to determine whether serum 25-hydroxyvitamin-D (25-OH-vitamin D) is a negative acute phase reactant and whether class of diagnosis modifies the association between C-Reactive Protein (CRP) and 25-OH-vitamin D. Methods: Multiple linear regression analysis was utilized to assess the association between CRP and 25-OH-vitamin D in 1,043 patients with acute and chronic diseases and normal volunteers. Results: After adjusting for confounding factors, the association between CRP and 25-OH-vitamin D was statistically significant. Class of diagnosis did not modify this association. Conclusions: 25-OH-vitamin D is demonstrated to be a negative acute phase reactant in this group of patients; Therefore, it is not an accurate marker of vitamin D status in the setting of inflammation. These findings support that 25-OH-vitamin D should be interpreted cautiously when CRP is elevated and that evaluating 25-OH-vitamin D in the context of CRP will improve accuracy of 25-OH-vitamin D interpretation.
Association between cigarette smoking and the vaginal microbiota: a pilot study
(Springer Nature, 2014-08-28) Brotman, Rebecca M; He, Xin; Gajer, Pawel; Fadrosh, Doug; Sharma, Eva; Mongodin, Emmanuel F; Ravel, Jacques; Glover, Elbert D; Rath, Jessica M
Smoking has been identified in observational studies as a risk factor for bacterial vaginosis (BV), a condition defined in part by decimation of Lactobacillus spp. The anti-estrogenic effect of smoking and trace amounts of benzo[a]pyrene diol epoxide (BPDE) may predispose women to BV. BPDE increases bacteriophage induction in Lactobacillus spp. and is found in the vaginal secretions of smokers. We compared the vaginal microbiota between smokers and non-smokers and followed microbiota changes in a smoking cessation pilot study. In 2010–2011, 20 smokers and 20 non-smokers were recruited to a cross-sectional study (Phase A) and 9 smokers were enrolled and followed for a 12-week smoking cessation program (Phase B). Phase B included weekly behavioral counseling and nicotine patches to encourage smoking cessation. In both phases, participants self-collected mid-vaginal swabs (daily, Phase B) and completed behavioral surveys. Vaginal bacterial composition was characterized by pyrosequencing of barcoded 16S rRNA genes (V1-V3 regions). Vaginal smears were assigned Nugent Gram stain scores. Smoking status was evaluated (weekly, Phase B) using the semi-quantitative NicAlert® saliva cotinine test and carbon monoxide (CO) exhalation. In phase A, there was a significant trend for increasing saliva cotinine and CO exhalation with elevated Nugent scores (P value <0.005). Vaginal microbiota clustered into three community state types (CSTs); two dominated by Lactobacillus (L. iners, L. crispatus), and one lacking significant numbers of Lactobacillus spp. and characterized by anaerobes (termed CST-IV). Women who were observed in the low-Lactobacillus CST-IV state were 25-fold more likely to be smokers than those dominated by L. crispatus (aOR: 25.61, 95 % CI: 1.03-636.61). Four women completed Phase B. One of three who entered smoking cessation with high Nugent scores demonstrated a switch from CST-IV to a L.iners-dominated profile with a concomitant drop in Nugent scores which coincided with completion of nicotine patches. The other two women fluctuated between CST-IV and L. iners-dominated CSTs. The fourth woman had low Nugent scores with L. crispatus-dominated CSTs throughout. Smokers had a lower proportion of vaginal Lactobacillus spp. compared to non-smokers. Smoking cessation should be investigated as an adjunct to reducing recurrent BV. Larger studies are needed to confirm these findings.
Association between community socioeconomic factors, animal feeding operations, and campylobacteriosis incidence rates: Foodborne Diseases Active Surveillance Network (FoodNet), 2004–2010
(Springer Nature, 2016-07-22) Rosenberg Goldstein, Rachel E.; Cruz-Cano, Raul; Jiang, Chengsheng; Palmer, Amanda; Blythe, David; Ryan, Patricia; Hogan, Brenna; White, Benjamin; Dunn, John R.; Libby, Tanya; Tobin-D’Angelo, Melissa; Huang, Jennifer Y.; McGuire, Suzanne; Scherzinger, Karen; Ting Lee, Mei-Ling; Sapkota, Amy R.
Campylobacter is a leading cause of foodborne illness in the United States. Campylobacter infections have been associated with individual risk factors, such as the consumption of poultry and raw milk. Recently, a Maryland-based study identified community socioeconomic and environmental factors that are also associated with campylobacteriosis rates. However, no previous studies have evaluated the association between community risk factors and campylobacteriosis rates across multiple U.S. states. We obtained Campylobacter case data (2004–2010; n = 40,768) from the Foodborne Diseases Active Surveillance Network (FoodNet) and socioeconomic and environmental data from the 2010 Census of Population and Housing, the 2011 American Community Survey, and the 2007 U.S. Census of Agriculture. We linked data by zip code and derived incidence rate ratios using negative binomial regression models. Community socioeconomic and environmental factors were associated with both lower and higher campylobacteriosis rates. Zip codes with higher percentages of African Americans had lower rates of campylobacteriosis (incidence rate ratio [IRR]) = 0.972; 95 % confidence interval (CI) = 0.970,0.974). In Georgia, Maryland, and Tennessee, three leading broiler chicken producing states, zip codes with broiler operations had incidence rates that were 22 % (IRR = 1.22; 95 % CI = 1.03,1.43), 16 % (IRR = 1.16; 95 % CI = 0.99,1.37), and 35 % (IRR = 1.35; 95 % CI = 1.18,1.53) higher, respectively, than those of zip codes without broiler operations. In Minnesota and New York FoodNet counties, two top dairy producing areas, zip codes with dairy operations had significantly higher campylobacteriosis incidence rates (IRR = 1.37; 95 % CI = 1.22, 1.55; IRR = 1.19; 95 % CI = 1.04,1.36). Community socioeconomic and environmental factors are important to consider when evaluating the relationship between possible risk factors and Campylobacter infection.
The Association between Cultural Views of Cancer and Colorectal Cancer Screening Behavior among Asian Americans in the Washington, D.C. Metropolitan Area
(2013) Jung, Mary; Lee, Sunmin; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Objective: To evaluate the association between Asian cultural views of cancer and colorectal cancer screening behavior among Asian Americans in the Washington, D.C. metropolitan area. Methods: A cross-sectional examination was conducted of 858 Chinese, Korean, and Vietnamese adults. Logistic regression was used to investigate the relationship between Asian cultural views (using 16-items from a previously developed scale) and colorectal cancer screening (self-reported yes/no). Results: When examining 10-point increases in continuous cultural views scores, a 12% (OR=0.88; 95% CI:0.82-0.97) and 7% (OR=0.93; 95% CI:0.87-1.00) decreased likelihood that an individual received screening were observed for herb use and self-care scores respectively. When examining categorical cultural views scores (Asian, Neutral, and Western), herb use and self-care were significantly associated with screening and showed a gradient effect after adjusting for age. Conclusion: Findings suggest that culturally appropriate interventions that address specific cultural views of cancer can potentially increase colorectal cancer screening among Asian Americans.
THE ASSOCIATION BETWEEN SUBMICROSCOPIC MALARIA INFECTION AND FEVER: FINDINGS FROM A CROSS-SECTIONAL STUDY IN MALAWI
(2019) Barrall, Angelica Lynne; Dyer, Typhanye V; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Individuals with submicroscopic malaria infection are an important reservoir for transmission, but the clinical consequences of these low-density parasitemia infections are poorly understood. Using cross-sectional data from six household-based surveys conducted during the dry and rainy seasons in Malawi from 2012 to 2014, this study examined the association between submicroscopic infection and fever in children and adults. For each survey, 900 households were recruited from three distinct ecological settings in southern Malawi to participate in the study (N=22,145). Overall prevalence of submicroscopic infection in the analytic sample was 8.1%. In a generalized linear mixed model accounting for clustering at the household and neighborhood levels and controlling for age and survey number, submicroscopic infection predicted fever in the dry season only (OR=1.66; 95% CI: 1.04, 2.66). Therefore, fever might not be a consistent marker of submicroscopic infection, but identification and treatment of low parasitemia infections is necessary to eliminate malaria transmission.
Association of Life Events with Depressive Symptoms among Puerto Rican Youth
(2014) Jaschek, Graciela; Carter-Pokras, Olivia D.; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
BACKGROUND: Early onset depressive symptoms have amplifying effects on the course of later depression, and serious personal, social and economic consequences throughout the life course. Little has been published regarding socio-demographic determinants of depression and possible mechanisms for the development of depressive symptoms among Puerto Rican youth. This study aims to examine the extent to which life events are associated with the development of depressive symptoms, and how place of residence, parental support, youth self-esteem and youth coping modify that association. METHODS: Secondary analyses were performed of data from the longitudinal Boricua Youth Study (three annual waves between 2000-2004). The sample consisted of 10-13 year old Puerto Rican youth living in New York and Puerto Rico with no depressive symptoms at wave 1, and complete information on depressive symptoms (DISC Predictive Scale which includes 9 significant predictors of depression)at waves 2 and/or 3. RESULTS: Depressive symptoms increase across waves with an increase in total, negative, or positive life events in general; and social adversity, death, and family environment life events specifically. Youth with low coping consistently had a higher number of depressive symptoms than youth with high coping regardless of number of total, negative or positive life events. Youth support from parents was found to be a significant confounder for all types of life events. Parent coping was a significant confounder for social adversity events. DISCUSSION: This study identifies various kinds of life events as risk factors that contribute to the development of depressive symptoms. Early onset depressive symptoms have amplifying effects on the course of later depression, and serious personal, social and economic consequences throughout the life course. Preventing the development of depressive symptoms at an early age should be a priority if we want to optimize the mental health and well-being of youth so that they can reach their full potential. Our findings could inform the development of a first-stage screening tool for youth at risk of developing depressive symptoms in community settings.
THE ASSOCIATION OF ORPHAN AND VULNERABLE CHILD (OVC) PRIMARY CAREGIVING, HOUSEHOLD WEALTH, AND FEMALE AUTONOMY ON WOMEN'S BODY MASS INDEX IN NAMIBIA, SWAZILAND AND ZAMBIA
(2013) Kanamori Nishimura, Mariano Juan; Carter-Pokras, Olivia D; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Background: This dissertation investigates factors associated with orphan and vulnerable child (OVC) caregivers' body mass index (BMI) in Namibia, Swaziland and Zambia. Methods: Secondary analyses were performed using cross-sectional data from Demographic Health Surveys conducted in 2006 and 2007. Manuscript 1 included de facto women from Namibia (n=6,638), Swaziland (n=3,285), and Zambia (n=4,497). Manuscript 2 included de jure women from Namibia (n=6,305), Swaziland (n=2,786), and Zambia (n=4,389). Manuscript 3 included married de jure women from Namibia (n=2,633), Swaziland (n=1,395), and Zambia (n=2,920). Statistical analyses using data from 20-49 year old women included weighted marginal means, logistic regression, and Sobel and Goodman tests. Results: Manuscript 1. OVC caregivers' overweight prevalence ranged from 26.98% (Namibia) to 61.3% (Swaziland). Namibian OVC caregivers were less likely to be overweight than non-OVC caregivers and non-caregivers not living with OVC. Swazi and Zambian OVC caregivers were more likely to be overweight than non-caregivers. In Namibia, women's age modified the effect of the association between OVC caregiving and overweight status. Manuscript 2. Namibian and Swazi OVC caregivers had lower Absolute Wealth Index (AWI) mean scores than non-OVC caregivers and non-caregivers. In Zambia, OVC caregivers had a lower mean AWI score than non-caregivers living with an OVC but a higher mean AWI score than non-OVC caregivers. In all countries, even small increases in household wealth (e.g., being a poorer women - 2 to 3 AWI items) were associated with higher odds for being overweight regardless of women's caregiving status. Manuscript 3. Women's educational attainment increased the odds for being overweight in Swaziland and Zambia, and decreased the odds for being underweight in Namibia. Decision-making autonomy mediated the association between AWI and OVC caregivers' BMI in Zambia (Z=2.13, p=0.03). Conclusions. As Africa is experiencing a nutritional and HIV/AIDS transition, overweight problems among OVC caregivers has emerged and should be addressed. These findings support the World Health Organization's recommendations that African countries should focus on addressing infectious diseases as well as the emergence of chronic diseases. Some African public health systems and OVC programs may face a new overweight epidemic alongside existing ones such as HIV/AIDS, tuberculosis, and malaria.
ASSOCIATION OF SERUM VITAMIN D AND KEY CO-NUTRIENTS IN RELATION TO HYPERTENSION: A CROSS-SECTIONAL STUDY BASED ON NHANES DATA
(2016) Barainca, Pamela; Carter-Pokras, Olivia; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Observational studies demonstrate strong associations between deficient serum vitamin D (25(OH)D) levels and cardiovascular disease. To further examine the association between vitamin D and hypertension (HTN), data from the 2003-2006 National Health and Nutrition Examination Survey were analyzed to assess whether the association between vitamin D and HTN varies by sufficiency of key co-nutrients necessary for metabolic vitamin D reactions to occur. Logistic regression results demonstrate independent effect modification by calcium, magnesium, and vitamin A on the association between vitamin D and HTN. Among non-pregnant adults with adequate renal function, those with low levels of calcium, magnesium, and vitamin D levels had 1.75 times the odds of HTN compared to those with sufficient vitamin D levels (p = <0.0001). Additionally, participants with low levels of calcium, magnesium, vitamin A, and vitamin D had 5.43 times the odds of HTN compared to those with vitamin D sufficiency (p = 0.0103).
Association of Types of Life Events with Depressive Symptoms among Puerto Rican Youth
(PLoS (Public Library of Science), 2016-10-27) Jaschek, Graciela; Carter-Pokras, Olivia D.; He, Xin; Lee, Sunmin; Canino, Glorisa
The main objective of this study was to examine the association between four types of adverse life events (family environment, separation, social adversity, and death) and the development of depressive symptoms among Puerto Rican youth. This was a secondary analysis using three waves (2000-2004) of interview data from the Boricua Youth Study of 10-13 year old Puerto Rican youth residing in New York and Puerto Rico with no depressive symptoms at baseline (n = 977). Depressive symptoms increased with an increase in social adversity, separation, death, and death events. Youth support from parents was a significant protective factor for all adverse events and parent coping was a protective factor in social adversity events. Relying on standard diagnostic tools is ideal to identify youth meeting the criteria for a diagnosis of depression but not useful to detect youth who present with subclinical levels of depression. Youth with sub-clinical levels of depression will not get treated and are at increased risk of developing depression later in life. Adverse life events are potentially relevant to use in conjunction with other screening tools to identify Puerto Rican youth who have subclinical depression and are at risk of developing depression in later adolescence.
Associations among food insecurity, dietary sodium and potassium intake levels, and hypertension: a cross-sectional study based on NHANES 2007-2010 data
(2014) Nothwehr, Ann; Carter-Pokras, Olivia; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Background: Food insecure persons may have diet patterns that include excessive sodium and inadequate potassium. These patterns contribute to greater risks of hypertension. Objective: Evaluate levels of association among food insecurity, dietary sodium and potassium intake levels and hypertension among NHANES 2007-2010 adult participants. Methods: Compared mean usual sodium and potassium intakes as well as mean usual sodium-potassium ratios for food secure and food insecure subpopulations. Developed regression models to predict intake levels and hypertension risk. Results: Mean usual sodium intake is not significantly different for food secure and food insecure participants. Mean usual potassium intake is significantly lower and mean usual sodium-potassium ratio is significantly higher for the food insecure subgroup. Controlling for age and household size, food insecure persons are 43% more likely to be hypertensive than food secure persons. Conclusion: Public health measures to decrease cardiovascular disease risk should include interventions designed for this vulnerable subpopulation.
ASSOCIATIONS BETWEEN AMBIENT PARTICULATE MATTER EXPOSURES, STROKE, AND MARKERS OF CARDIOVASCULAR INFLAMMATION
(2017) Fisher, Jared A.; Puett, Robin C; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Stroke is a leading cause of morbidity and mortality in the United States with 795,000 people experiencing a new or recurrent stroke every year. Identifying modifiable risk factors for stroke should therefore be considered a research priority. While associations between ambient exposure to air pollution and other cardiovascular diseases are well established in the literature, the evidence linking particulate matter (PM) air pollution exposures to the risk of ischemic or hemorrhagic stroke remains equivocal. Furthermore, the exact pathophysiologic mechanisms by which exposure to PM may lead to cerebrovascular events are not yet fully understood. Hypothesized pathways include the mediation of effects through a combination of inflammatory responses, autonomic dysregulation, and/or vascular endothelial disturbances. This dissertation addresses existing gaps in the literature in three separate studies. Two time-stratified case-crossover studies examined the association between short-term PM exposures and stroke risk, one in the Health Professionals Follow-up Study (HPFS) and the other among a large database of Maryland stroke hospitalizations. Conditional logistic regression models were used to examine associations by stroke subtype, population subgroups, and clinically-relevant variables. Our third study took place within the Nurses’ Health Study cohort. Multivariable linear regression models were used to examine the associations between PM and residential distance to road exposures and four inflammatory biomarkers (CRP, IL-6, fibrinogen, and ICAM-1). We found positive significant associations between PM10 and ischemic stroke events in the HPFS cohort, and associations were elevated for nonsmokers, aspirin nonusers, and those without a history of high cholesterol. Concentrations were elevated for both CRP and IL-6 among participants who lived close to a major roadway, but no significant results were found by estimated PM exposure. This work provides additional evidence that PM exposure is associated with ischemic stroke and adds to the current literature that those not currently taking aspirin and those without a history of high cholesterol may be at elevated risk. Although the direct role of inflammatory processes requires more investigation, this work does provide additional evidence that proximity to traffic may influence cardiovascular-related inflammation.
Associations between Urinary Phthalates and Metabolic Syndrome in NHANES 2005-2010
(2015) Haque, Mefruz Salwa; Dallal, Cher M; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Phthalates, commonly used to make plastics more durable, are a group of endocrine disrupting chemicals (EDC), with potential for adverse metabolic consequences. Associations between exposure to 13 phthalate metabolites and the prevalence of metabolic syndrome (MetS) were examined among 5,409 U.S adults ≥ 18 years of age, who participated in the National Health and Nutrition Examination Survey from 2005-2010. MetS was assessed using clinical and questionnaire data. Odds Ratio (OR) and 95% Confidence Intervals (CI) adjusting for age, creatinine and key confounders, were estimated with multivariable logistic regression. Positive associations were observed between individual phthalate metabolites and MetS: (MCOP OR=1.31, 95% CI=1.40, 1.64, p-trend<.01; MCPP OR=1.39, 95% CI=1.09, 1.77, p-trend=0.01). In gender stratified analyses, findings with MCOPP and MCPP were restricted to women only. Phthalate metabolites may increase the prevalence of MetS; however, further studies are needed to better understand the role of EDCs in the development of MetS.
Biomarker Categorization in Transcriptome Meta-analysis by Statistical significance, Biological Significance and Concordance
(2020) Ye, Zhenyao; Ma, Tianzhou; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
With the advancement of high-throughput technology, transcriptomic studies have been accumulated in the public domain. Meta-analysis combines multiple studies on a related hypothesis and improves the statistical power and reproducibility of single studies. However, a majority of existing meta-analysis methods only consider the statistical significance. We propose a novel method to categorize biomarkers by simultaneously considering statistical significance, biological significance (large effect size), and concordance patterns across studies, accounting for the complex study heterogeneity that exists in most meta-analysis problems. We conducted simulation studies and applied our method to Gynecologic and breast cancer RNA-seq data from The Cancer Genome Atlas to show its strength as compared to adaptively-weighted Fisher’s method. We found several major biomarker categories according to their cross-study patterns, and these categories are enriched in very different sets of pathways, offering different biological functions for future precision medicine.