BACKGROUND: A growing body of research has suggested that exposure to traffic-related emissions is associated with numerous adverse health effects including prevalence and severity of symptoms of asthma, hospitalizations for acute myocardial infarctions, and cardiovascular-related mortality. No previous studies have assessed the association between proximity to traffic and respiratory and cardiovascular outcomes across all age groups. OBJECTIVE: The purpose of this study was to assess the association between proximity to traffic emissions within the City of Atlanta and respiratory and cardiovascular 911 Emergency Management Service (EMS) calls and subsequent emergency department (ED) visits. METHODS: Case and control diagnostic groups were established for 5,450 EMS calls received between 2004 and 2008 from residents of the City of Atlanta based on ICD-9 codes assigned within the ED. Case diagnostic groups included asthma, cardiovascular outcomes, and stroke. Gastrointestinal diagnostic groups were selected as controls. Cumulative traffic within a 100 m buffer of the call origination location was used as an indicator of exposure to traffic emissions. Using a case-control study design, the associations between exposure to traffic emissions and the case diagnostic groups were evaluated using logistic regression, controlling for potential confounding factors including age, gender, ethnicity, and socio-economic status (SES). Subgroup analyses were performed to evaluate differences by select age categories, gender, and SES. P-values of <0.05 and 95% confidence intervals (CI) were used to determine statistical significance. RESULTS: Increased cumulative traffic near the call location was associated with an increase in the odds of an EMS call and ED visit for cardiovascular outcomes compared to the control diagnostic group even after adjustment for confounding factors (OR = 1.07; 95% CI ,1.01-1.12). The strongest effects were among men and individuals aged 40-75 years. Increased cumulative traffic was also associated with an increased odds of an EMS call and ED visit for stroke among individuals aged 18-39 years after adjusting for confounding (OR = 1.16; 95% CI, 1.01-1.34). No statistically significant associations were found between increased cumulative traffic and the odds of an EMS call and ED visit for asthma. CONCLUSION: These results provide additional evidence that proximity to traffic is associated with adverse cardiovascular outcomes and stroke in certain age groups.

Primary-care-related emergency department (PCR-ED) visits by Hispanic patients enrolled in a not-for-profit Medi-Cal and Medicare health plan resulted in longer wait times in the emergency department (ED) at a regional medical center in Southern California. This congestion decreased access for those with true emergencies, created capacity issues, increased ED length of stay, and resulted in potential safety risks. This project focused on decreasing PCR-ED visits in the Hispanic population using patient navigators in Southern California. Applying the health belief model and Lippitt's theory of change, this doctoral project involved the creation and implementation of a culturally appropriate, population-specific patient navigator model for the Hispanic population. Evaluation of outcomes was accomplished using electronic health record (EHR) results, which demonstrated a reduction of PCR-ED visits and revisits. The project exceeded the goal of 10% reduction in PCR-ED visits and revisits in the target population and resulted in a 14.31% reduction of PCR-ED visits and revisits within 1 month of implementation. Emergency Severity Index levels, wait time associated with each Emergency Severity Index level, and visits of the targeted Hispanic population enrolled in the health plan were analyzed to evaluate the success of the program. This project may lead to improvements in nursing practice and positive social change by supporting population health management and continuum of care to a primary care physician through safe and efficient patient navigation to treatment and care.

Preterm birth (< 37 weeks gestation) is a major health burden for affected children. Although the risk of health problems increases as the gestational age decreases, research in the last decades has revealed that even late preterm infants born at 34-36 weeks gestational age have higher mortality and morbidity than term infants. Because late preterm infants constitute three fourths of preterm infants, they are important from both public health and health policy perspectives. This doctoral thesis sought to answer important knowledge gaps in health service utilization of late preterm infants via three studies. Study A, a systematic review and meta-analysis comparing health service utilizations of late preterm infants with those of term infants, found that late preterm infants had increased hospitalization compared with term infants that persisted from the neonatal period through adolescence. Study B is a cohort study evaluating the re-admissions and emergency department visits by late preterm and term singletons and twins for the first 5 years after birth. Study B demonstrated that late preterm infants had higher re-admission rates than term infants although differences in twins were less pronounced than in singletons. Study C is a population-based cohort study with cost analyses assessing the health care costs and resource utilization related to three different discharge timings of late preterm and term singletons: early (< 48 hours), late (48-71 hours), and very-late (72-95 hours) discharge after birth. Study C found that early discharge was not associated with the reduction of health care cost in late preterm infants, and instead was associated with an increase in the cost in term infants over the first year after birth. These findings are useful for parents, care providers, health policy makers, and guideline developers to provide optimal care for late preterm infants. / Thesis / Doctor of Philosophy (PhD)

Objective: To determine whether continuity of care (COC) reduces emergency department (ED) visits and/or readmission in adolescents with psychiatric disorders. Methods: A retrospective cohort of adolescents discharged with psychiatric disorder between April 1, 2002 and March 1, 2004 was identified using hospital administrative databases. Good COC was defined as at least one aftercare contact in 30 days. Confounding by patient characteristics was adjusted for by propensity-score-matching of good and poor COC adolescents. Cox PH was used to analyze time to outcome. Results: 48.77% of adolescents had good COC. 38.39% of adolescents had ED visit or readmission in the year post-discharge. Good COC increased risk of readmission (HR = 1.38 (1.14 – 1.66)), but not of ED visits (HR = 1.14 (0.95 – 1.37)). Conclusions: COC increased risk of readmission by 38% but did not increase risk of ED visits. These findings are contextualized. Implications to adolescent mental health service delivery are discussed.

Objective: To determine whether continuity of care (COC) reduces emergency department (ED) visits and/or readmission in adolescents with psychiatric disorders. Methods: A retrospective cohort of adolescents discharged with psychiatric disorder between April 1, 2002 and March 1, 2004 was identified using hospital administrative databases. Good COC was defined as at least one aftercare contact in 30 days. Confounding by patient characteristics was adjusted for by propensity-score-matching of good and poor COC adolescents. Cox PH was used to analyze time to outcome. Results: 48.77% of adolescents had good COC. 38.39% of adolescents had ED visit or readmission in the year post-discharge. Good COC increased risk of readmission (HR = 1.38 (1.14 – 1.66)), but not of ED visits (HR = 1.14 (0.95 – 1.37)). Conclusions: COC increased risk of readmission by 38% but did not increase risk of ED visits. These findings are contextualized. Implications to adolescent mental health service delivery are discussed.