Injection drug use has reached epidemic rates in the United States. Persons who inject drugs (PWID) are at increased risk for blood borne diseases such as HIV and HCV, due to their injection behaviors. Different factors interact and may determine injectors’ sharing behaviors. Age has been determined to be a significant predictive variable in numerous studies. This study attempted to show that length of time injecting is also a significant predictor of sharing behaviors. Using multivariate logistic regression, this study examines length of time an individual has been injecting as it relates to receptive syringe sharing. Receptive syringe sharing, using a syringe after another individual, presents the greatest risk for contracting blood borne pathogens such as HIV and hepatitis C. Utilizing National HIV Behavioral Surveillance System data from PWID in Philadelphia, PA, results indicate that neither age of the injector nor experience are significant predictors of RSS. However, history of being homeless and race, identifying as White, non-Hispanic, are both significant predictors of RSS in an adjusted multivariate model. Based on these findings, current strategies to address risk behavior may not adequately address those most at risk for RSS. This paper concludes with recommendations for increased targeted interventions among those PWID with greater housing instability. The aim of this recommendation is to decrease receptive syringe sharing and ameliorate HIV and HCV infection risk. / Public Health

Introduction: Overweight and obesity are growing problems in the United States, as these conditions are frequently associated with chronic diseases that may lead to morbidity and premature mortality. Behavioral interventions for weight loss have shown promise in decreasing body weight and improving health in adults with overweight and obesity. However, weight loss interventions may be undermined by dietary lapses. Stress is a known risk factor of overweight and obesity, and may affect dietary lapse as it has been associated with enhanced appetite and increased energy intake. Therefore, studying behavioral treatment strategies and their possible role as modifiers of the effect of stress on lapse may help inform improved strategies for the future. Objectives: This secondary analysis aims to study the effectiveness of acceptance-based strategies in reducing dietary lapses throughout a 12-month weight loss program compared to a standard behavioral treatment. Furthermore, it will investigate whether the effect of stress on lapse occurrence is modified by treatment condition. Methods: Data analyses were performed using ecological momentary assessment survey data obtained from 189 participants with overweight and obesity that had participated in a 12-month weight loss program, and had been randomized to either acceptance-based or standard behavioral treatment. Mixed effects regression models with information on participants’ stress level and lapse occurrence collected at multiple instances at baseline (first 3 weeks), mid-treatment (at 6 months), and end-of-treatment (at 12 months) were used to answer the research questions presented in this study. Results: The acceptance-based treatment (ABT) was shown to decrease the odds of lapsing compared to the standard behavioral treatment (SBT) at mid-treatment in the model controlling for gender (OR = 0.716, CI [0.516, 0.994]). In the model with data from female participants only, ABT was also shown to decrease the odds of lapsing compared to SBT (OR = 0.686, CI [0.489, 0.964]). At end-of-treatment the decrease in odds of lapsing was not statistically significant for ABT compared to SBT. Between-subject stress, lapse frequency at baseline, and gender were strong predictors of lapse at mid- and end-of-treatment; however, treatment condition did not modify the effect of between-subject stress on lapse. Although treatment condition did not modify the effect of within-subject stress level on lapse, the main effect of treatment condition (i.e., within-subject stress level equal to zero) showed a decrease in the odds of lapsing for individuals receiving ABT compared to SBT at mid-treatment in the model controlling for gender (OR = 0.718, CI [0.517, 0.997]), and in the model with data from female participants only (OR = 0.688, CI [0.490, 0.966]). Conclusion: This study suggests that acceptance-based strategies are more effective at reducing dietary lapse when compared to cognitive strategies delivered to adults with overweight and obesity during an intensive behavioral intervention for weight loss. A better understanding of the mechanisms through which acceptance-based strategies improve dietary behavior may be achieved with the inclusion of potential mediators of the association in the analytical models. / Epidemiology

There is growing recognition that ignoring missing data requires stronger assumptions than addressing them. Numerous effective methods have emerged for handling missing data under so-called ignorable missing data conditions, effective treatment of non-ignorable missing data (missing not at random, MNAR) remains an open problem, typically requiring that missing data be modeled explicitly. Most previous research applies a single statistical model to the entire data set, although some previous research suggests that imputations based on a subset of similar cases may prove more effective with MNAR data. The primary aim of this study was to determine if imputing missing data by a method which utilizes only local information could provide results comparable to methods based on explicit modeling of missing data. This thesis reports the results of 4 experiments evaluating dynamic cluster-based imputation (DCI) to impute missing post-test data in simulated cluster-randomized trial data under conditions that previous research showed no standard methods to be effective. This method identifies a set of statistical proximal observations (indexed by K) and uses a subset of them (indexed by R) to perform imputations. Both parameters can be tuned to a specific problem with previous research suggesting that K=50 and R=9 was optimal for most applications. Compared to common methods for handling non-ignorable missing data (listwise deletion, LOCF, pattern-mixture modeling, Diggle-Kenward modeling), results of the experiments suggest that indicators variables for the pattern of missing observations was included in the imputation model, DCI had comparable bias and coverage rates to "best practice" methods of Diggle-Kenward and pattern mixture models, but at the cost of larger standard errors. Thus results support for the idea that imputation based on a subset of similar observations could be more accurate than imputation using all cases. / Epidemiology

The preconception period (i.e., the period of time before an individual becomes pregnant) is increasingly recognized as a critical time period for health promotion. Preconception health interventions, including physician counseling, have demonstrated promise in encouraging health-promoting behaviors. This dissertation evaluates two historically understudied elements of preconception health, oral and sexual health, with an emphasis on generating insights to inform interventions. Our first study used latent class analysis in a population of preconception pregnancy planners to identify groups similar in terms of modifiable health behaviors. We then evaluated the extent to which group membership was associated with self-rated oral health and oral healthcare engagement to identify whether oral health-related behaviors clustered with other health behaviors in the preconception period. We found that healthy behaviors clustered into three groups, and that groups with higher probability of less healthy behaviors were less likely to be actively engaged in oral healthcare. Our second study estimated the effect of a history of preconception periodontitis on spontaneous abortion. We found that a self-reported history of adult tooth mobility was associated with a higher risk of spontaneous abortion, but that two other self-report measures of periodontitis (a history of diagnosis of and treatment for periodontitis) had no appreciable association. Finally, we evaluated the effect of preconception sexual dysfunction and distress on time to pregnancy. We report an association between lower sexual function, higher distress related to sexual function, and frequent painful intercourse and a prolonged time to pregnancy. The findings of these studies contribute insights into the salience of oral and sexual health in the preconception period and have the potential to inform interventions for preconception health promotion. / 2026-05-10T00:00:00Z

Adverse pregnancy outcomes are a major contributor to morbidity and mortality and constitute a significant burden on individuals, families, and the healthcare system. Understanding the risk factors for adverse birth outcomes is crucial for prevention and intervention. The aim of this dissertation was to conduct three studies to assess the risk of common and rare medical, behavioral, and pharmacologic exposures on birth defects, low birth weight, preterm birth, and small-for-gestational age, and to compare logistic regression and machine learning methods to predict small-for-gestational age (SGA) using data from the National Birth Defects Prevention Study (NBDPS; 1997–2011). In Study 1, we assessed the extent to which first trimester nausea and vomiting of pregnancy (NVP) and its treatments were associated with 37 specific cardiac and non-cardiac birth defects. We hypothesized that gestational parents with NVP would have decreased risks of oral clefts and hypospadias and among parents who treat their NVP, common medications and vitamin remedies would not increase risks of specific birth defects. We found compared to no NVP, gestational parents with NVP had ≥10% reduction in risk of cardiac and non-cardiac defects overall, and of 18 specific defects. Over-the-counter antiemetic use, compared to untreated NVP, was associated with ≥10% increase in risk for 9 defects, whereas use of prescription antiemetics increased risk ≥10% for 7 defects. We observed increased risks for promethazine and tetralogy of Fallot (aOR:1.49, 95% CI: 1.05–2.10), promethazine and craniosynostosis (1.44, 1.08–1.92), ondansetron and cleft palate (1.66, 1.18–2.31), pyridoxine and heterotaxy (3.91, 1.49–10.27), and pyridoxine and cataracts (2.57, 1.12–5.88). In Study 2, we assessed the extent to which nausea and vomiting of pregnancy, according to timing, duration, and severity, and its treatments were associated with adverse pregnancy outcomes, including low birth weight, small-for-gestational age, preterm delivery and gestational length. Additionally, we examined if these effects are modified by periconceptional multivitamin use. We hypothesized that gestational parents with NVP would have a decreased risk of low birth weight, small-for-gestational age, preterm birth, and gestational length compared to those without NVP. Among those who treated their NVP, we hypothesized specific treatments would not be associated with an elevated risk of adverse birth outcomes compared to parents with NVP who do not use any treatments. Additionally, we hypothesized gestational parents with NVP who used multivitamins periconceptionally would have a stronger protective effect for the adverse birth outcomes. We found any versus no NVP was not associated with any of the adverse pregnancy outcomes of interest. NVP in months 4–6 (aOR 1.21, 95% CI: 1.00, 1.47) and 7–9 (aOR 1.57, 95% CI: 1.22, 2.01) of pregnancy were associated with an increase in the risk of preterm birth. NVP lasting one trimester in duration was associated with decrease in risk of SGA (aOR: 0.74, 95% CI: 0.58, 0.95), and NVP present in every trimester of pregnancy had a 50% increase in risk of preterm birth (aOR: 1.50, 95% CI: 1.11, 2.05). For NVP in months 7–9 and preterm birth, ORs were elevated for moderate (aOR: 1.82, 95% CI: 1.26, 2.63), and severe (aOR: 1.53, 95% CI: 1.06, 2.19) symptoms. NVP was not significantly associated with low birth weight. We observed no increased risk of adverse outcomes associated with use of the medication. We could not draw conclusions of interactive effects of multivitamins and NVP because of small sample sizes. In study 3, we explored using machine learning methods compared with regression methods to predict small-for-gestational age from a variety of gestational parental medical, behavioral, and demographic factors. We hypothesized several important predictive factors for SGA, representing diverse mechanistic pathways, would emerge, and machine learning methods would yield greater predictive value than logistic regression. We created four main models to predict SGA: two using logistic regression methods, and two using random forest methods, using all literature-informed or subsets of variables. With variable selection and other tuning methods, we attempted to maximize predictive ability. However, the models demonstrated low accuracy in predicting SGA, with, contrary to our hypothesis, a slight advantage of the logistic regression models. / 2026-05-10T00:00:00Z

Chronic health conditions impact health throughout the life course, and their increase in prevalence in recent years has made them a public health priority. Chronic conditions affect about one-third of individuals of childbearing age and increase the risk of adverse pregnancy outcomes—however, the examination of modifiable health factors and multimorbidity on adverse perinatal outcomes, and patterns of postpartum healthcare use are less understood in this population. This dissertation aims to address these research areas to further understand the impact of chronic conditions in the preconception, perinatal, and postpartum period. Study 1 describes trends in sociodemographic and periconceptional behavioral health factors among individuals with pre-pregnancy chronic conditions and their association with preterm delivery and small-for-gestational age (SGA) using U.S., population-based case-control studies. From 1997–2001 to 2014–2019, the prevalence of pre-pregnancy conditions increased across all sociodemographic groups. Prevalence of unintended pregnancy and delayed prenatal care remained consistent across the study period and did not vary by chronic condition status; while increases in folic acid use and decreases in smoking were observed, with a higher prevalence among individuals with chronic conditions. Non-Hispanic Black and Hispanic/Latine individuals, regardless of chronic condition status, more frequently reported delayed prenatal care and unintended pregnancy, and lower prevalence of folic acid use. Individuals with a pre-pregnancy body mass index of 18.5–24.9 kg/m2 had reduced odds of preterm delivery, while intended pregnancy, folic acid use, timely prenatal care, and no smoking reduced the odds of SGA. Study 2 evaluates the association between multimorbidity and adverse perinatal outcomes; and describes the clustering of chronic conditions using latent class analysis (LCA) among a retrospective delivery cohort from a safety-net hospital. Multimorbidity was associated with increased risks in hypertensive disorders of pregnancy, preterm delivery, low birthweight, stillbirth, placental abruption, and prolonged hospital stay, while no meaningful difference was found for gestational diabetes and intrapartum hemorrhage. LCA resulted in a 3-class model: Class 1 was characterized by mood/anxiety and substance use disorders; Class 2 was defined by higher weight and chronic hypertension; and Class 3 was characterized by reproductive conditions and infertility. Classes were distributed distinctly across sociodemographic sub-groups. Study 3 examines the relationship between pre-pregnancy chronic conditions and variation, frequency, and timing of postpartum healthcare use in the 60 days after delivery discharge. Overall, 87% of individuals had at least one postpartum visit—74% had a preventative visit, 51% had a problem visit, 16% had an emergency department (ED) visit, and 4% had a hospital readmission. Compared to individuals without chronic conditions, individuals with chronic conditions had a higher risk and frequency of problem visits, ED visits, and hospital readmissions. A majority of individuals had a combination of visit types beyond preventative visits, regardless of chronic condition status. More than half of ED visits and readmissions occurred within the first two weeks postpartum. The findings of this dissertation highlight the need to reconceptualize reproductive, perinatal, and postpartum models of care that address the complex healthcare needs of individuals with chronic conditions, especially among historically minoritized populations who bear a disproportionate burden of chronic conditions and adverse perinatal outcomes. / 2026-05-16T00:00:00Z

Malaria infection has been and continues to be a serious public health concern that has mystified many in the public health care industry. One area in Sub Saharan Africa that continues to feel the devastating effects of malaria is in Nairobi, Kenya. This qualitative research study explored the attitudes of women in Nairobi, Kenya and how they view intervention measures already introduced by public health care experts in fighting malaria. The phenomenological research approach used purposeful sampling to recruit 16 women from Nairobi, Kenya to participate in semi-structured, open-ended interviews. The ecological systems theory was used as a lens of analysis to help illuminate the views of women on already-introduced malaria intervention measures in Nairobi, Kenya. Nvivo 10 helped manage data and the interpretative phenomenological analysis was used to analyze data and identify themes and subthemes through coding. The findings from this study indicate that (a) there is a disconnect within the systems, especially between public health officials and ordinary citizens, and (b) ordinary citizens felt that intervention measures already introduced have not been effectively implemented. The recommendations derived from the study will improve relationships between public health officials and ordinary citizens in order to effectively implement malaria control measures already introduced. This study will benefit public health officials, ordinary citizens in Nairobi, and other health care providers all over the world. This study contributes to social positive change by providing greater insight on already-introduced mosquito intervention measures.

Prostate cancer (CaP) remains the most commonly diagnosed cancer and second leading cause of cancer mortality among men in several ethnic groups in the United States. Lower CaP incidence among Asian men has been attributed to increased intake of soy derived phytoestrogens (SDPs); however, its association has not been extensively explored in U.S. men. The purpose of this study was to determine the effect size of serum prostate specific antigen (sPSA) and serum estradiol (sE2) following dietary SDP intervention. The study was based on an original conceptual model that aims to avert early prostate tissue damage through identification of critical prevention endpoints. Research questions examined the correlation between dietary SDPs and sPSA and sE2 levels. This quantitative meta-analysis study used data abstracted from 8 randomized controlled trials yielding 530 participants ages 50-85. Outcome specific meta-analysis using the random effect model adjusted for heterogeneity and determined cumulative effect size that favored intervention. Odds ratios established a positive correlation between intake of dietary SDP and detection of serum SDP (sSDP) among treated groups. Positive correlations between both dietary and sSDP with sE2 levels, and inverse correlations between both dietary and sSDP with sPSA levels, were indicated among treated compared to placebo groups. Hedges' g, correlation, and standardized mean difference statistics confirmed analyses. Implications for positive social change include developing professional dietary standards to use SDPs for CaP chemoprevention among U.S. and other men, as well as a medical option for treatment of CaP. Further research exploring mechanisms of SDP action on hormones may be beneficial to men at risk for CaP and individuals at risk for other cancers linked to changes in hormonal levels.

Waterpipe (WP; hookah, shisha, narghile) has re-emerged as a global epidemic of tobacco smoking mainly among young people. Although WP smokers show symptoms of nicotine dependence (ND) and face difficulty quitting, no study has examined the early symptoms and factors associated with ND among young WP smokers. Using baseline data from the Waterpipe Dependence in Lebanese Youth (WDLY) study, this research investigated the appearance and timing of early symptoms, factors, and WP-specific smoking patterns associated with ND symptoms among 160 adolescents (mean age ± SD =14.0 ± 1.1 years at baseline) from 8th and 9th grades who reported WP use in the past 30 days. ND symptoms were assessed using Hooked on Nicotine Checklist (HONC) and the full syndrome of ND was evaluated using the International Classification of Diseases-10th revision (ICD-10 ND). Our analysis shows that 71.3% of WP smokers endorsed at least one HONC symptom, 38.1% developed ICD-10 ND, with craving (25%), feeling addicted (22.5%), and failed quit attempts (14.3%) were the most commonly endorsed early symptoms of ND. The first HONC symptom and full ICD-10 ND were reached 10.9 and 13.9 months, respectively, after the initiation of WP use. Results from multivariable regression models show that depressive symptoms, lower self-esteem, and having at least one sibling who smokes WP were associated with the presence of ND symptoms, while enrollment in public schools, smoking WP ≥30 minutes per session, and believing that cigarette smoking is harmful to health were associated with a higher number of ND symptoms. Smoking a whole WP without sharing and being in 9th grade were associated with the presence and endorsement of a higher number of ND symptoms. These findings suggest that a large proportion of adolescents experience symptoms of ND within a short time period of initiating WP use. Moreover, we identified specific factors that put adolescents at a higher odds of developing ND symptoms. Therefore, WP prevention and intervention strategies may have greatest impact by educating youth about the harmful and addictive properties of WP, teaching them positive coping skills, targeting those enrolled in public schools, and addressing WP use by family members.

No description available.