[Show abstract][Hide abstract] ABSTRACT: Background
Emergency department (ED) visit and hospital admissions (HA) data have been an indispensible resource for assessing acute morbidity impacts of air pollution. ED visits and HAs are types of health care visits with similarities, but also potentially important differences. Little previous information is available regarding the impact of health care visit type on observed acute air pollution-health associations from studies conducted for the same location, time period, outcome definitions and model specifications.
As part of a broader study of air pollution and health in St. Louis, individual-level ED and HA data were obtained for a 6.5 year period for acute care hospitals in the eight Missouri counties of the St. Louis metropolitan area. Patient demographic characteristics and diagnostic code distributions were compared for four visit types including ED visits, HAs, HAs that came through the ED, and non-elective HAs. Time-series analyses of the relationship between daily ambient ozone and PM2.5 and selected cardiorespiratory outcomes were conducted for each visit type.
Our results indicate that, compared with ED patients, HA patients tended to be older, had evidence of greater severity for some outcomes, and had a different mix of specific outcomes. Consideration of ‘HA through ED’ appeared to more effectively select acute visits than consideration of ‘non-elective HA’. While outcomes with the strongest observed temporal associations with air pollutants tended to show strong associations for all visit types, we found some differences in observed associations for ED visits and HAs. For example, risk ratios for the respiratory disease-ozone association were 1.020 for ED visits and 1.004 for ‘HA through ED’; risk ratios for the asthma/wheeze-ozone association were 1.069 for ED visits and 1.106 for ‘HA through ED’. Several factors (e.g. age) were identified that may be responsible, in part, for the differences in observed associations.
Demographic and diagnostic differences between visit types may lead to preference for one visit type over another for some questions and populations. The strengths of observed associations with air pollutants sometimes varied between different health care visit types, but the relative strengths of association generally were specific to the pollutant-outcome combination.
Environmental Health 09/2012; 11(1). DOI:10.1186/1476-069X-11-70 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Racial disparities persist in access to renal transplantation in the United States, but the degree to which patient and neighborhood socioeconomic status (SES) impacts racial disparities in deceased donor renal transplantation access has not been examined in the pediatric and adolescent end-stage renal disease (ESRD) population. We examined the interplay of race and SES in a population-based cohort of all incident pediatric ESRD patients <21 years from the United States Renal Data System from 2000 to 2008, followed through September 2009. Of 8452 patients included, 30.8% were black, 27.6% white-Hispanic, 44.3% female and 28.0% lived in poor neighborhoods. A total of 63.4% of the study population was placed on the waiting list and 32.5% received a deceased donor transplant. Racial disparities persisted in transplant even after adjustment for SES, where minorities were less likely to receive a transplant compared to whites, and this disparity was more pronounced among patients 18-20 years. Disparities in access to the waiting list were mitigated in Hispanic patients with private health insurance. Our study suggests that racial disparities in transplant access worsen as pediatric patients transition into young adulthood, and that SES does not explain all of the racial differences in access to kidney transplantation.
American Journal of Transplantation 02/2012; 12(2):369-78. DOI:10.1111/j.1600-6143.2011.03888.x · 5.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Racial disparities in access to renal transplantation exist, but the effects of race and socioeconomic status (SES) on early steps of renal transplantation have not been well explored. Adult patients referred for renal transplant evaluation at a single transplant center in the Southeastern United States from 2005 to 2007, followed through May 2010, were examined. Demographic and clinical data were obtained from patient's medical records and then linked with United States Renal Data System and American Community Survey Census data. Cox models examined the effect of race on referral, evaluation, waitlisting and organ receipt. Of 2291 patients, 64.9% were black, the mean age was 49.4 years and 33.6% lived in poor neighborhoods. Racial disparities were observed in access to referral, transplant evaluation, waitlisting and organ receipt. SES explained almost one-third of the lower rate of transplant among black versus white patients, but even after adjustment for demographic, clinical and SES factors, blacks had a 59% lower rate of transplant than whites (hazard ratio = 0.41; 95% confidence interval: 0.28-0.58). Results suggest that improving access to healthcare may reduce some, but not all, of the racial disparities in access to kidney transplantation.
American Journal of Transplantation 02/2012; 12(2):358-68. DOI:10.1111/j.1600-6143.2011.03927.x · 5.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Acute lower respiratory illnesses (ALRI) are the leading cause of death among children <5 years. Studies have found that biomass cooking fuels are an important risk factor for ALRI. However, few studies have evaluated the influence of natural household ventilation indicators on ALRI. The purpose of this study was to assess the association between cooking fuel, natural household ventilation, and ALRI. During October 17, 2004–September 30, 2005, children <5 years living in a low-income neighborhood of Dhaka, Bangladesh, were assessed weekly for ALRI and surveyed quarterly about biomass fuel use, electric fan ownership, and natural household ventilation (windows, ventilation grates, and presence of a gap between the wall and ceiling). Bivariate and multivariate analyses were performed using generalized estimating equations. Six thousand and seventy-nine children <5 years enrolled during the study period (99% participation) experienced 1291 ALRI. In the multivariate model, ≥2 windows [OR = 0.75, 95% CI = (0.58, 0.96)], ventilation grates [OR = 0.80, 95% CI = (0.65, 0.98)], and not owning an electric fan [OR = 1.50, 95% CI = (1.21, 1.88)] were associated with ALRI; gap presence and using biomass fuels were not associated with ALRI. Structural factors that might improve household air circulation and exchange were associated with decreased ALRI risk. Improved natural ventilation might reduce ALRI among children in low-income families.
The World Health Organization has stated that controlling pneumonia is a priority for achieving the fourth Millennium Development Goal, which calls for a two-third reduction in mortality of children <5 years old compared to the 1990 baseline. Our study represents an important finding of a modifiable risk factor that might decrease the burden of respiratory illness among children living in Bangladesh and other low-income settings similar to our study site. We found that the existence of at least two windows in the child’s sleeping room was associated with a 25% decreased ALRI risk. Increasing available natural ventilation within the household in similar settings has the potential to reduce childhood mortality because of acute lower respiratory illnesses.
Indoor Air 10/2011; 22(2):132-9. DOI:10.1111/j.1600-0668.2011.00754.x · 4.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Acute respiratory infections (ARI) are the leading cause of death worldwide in children aged <5 years, and understanding contributing factors to their seasonality is important for targeting and implementing prevention strategies. In tropical climates, ARI typically peak during the pre-rainy and rainy seasons. One hypothesis is that rainfall leads to more time spent indoors, thus increasing exposure to other people and in turn increasing the risk of ARI. A case-crossover study design in 718 Bangladeshi children aged <5 years was used to evaluate this hypothesis. During a 3-month period with variable rainfall, rainfall was associated with ARI [odds ratio (OR) 2·97, 95% confidence interval (CI) 1·87-4·70]; some evidence of an increased strength of association as household crowding increased was found (≥3 people/room, OR 3·31, 95% CI 2·03-5·38), but there was a lack of association in some of the most crowded households (≥5 to <6 people/room, OR 1·55, 95% CI 0·54-4·47). These findings suggest that rainfall may be increasing exposure to crowded conditions, thus leading to an increased risk of ARI, but that additional factors not captured by this analysis may also play a role.
Epidemiology and Infection 03/2011; 140(1):78-86. DOI:10.1017/S0950268811000252 · 2.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Relationships between ambient air pollution levels during pregnancy and adverse pregnancy outcomes have been investigated using one of three analytic approaches: ambient pollution levels have been contrasted over space, time or both space and time. Although the three approaches share a common goal, to estimate the causal effects of pollution on pregnancy outcomes, they face different challenges with respect to confounding.
A framework based on counterfactual effect definitions to examine issues related to confounding in spatial, temporal, and spatial-temporal analyses of air pollution and pregnancy outcomes is presented, and their implications for inference are discussed.
In spatial analyses, risk factors that are spatially correlated with pollution levels are confounders; the primary challenges relate to the availability and validity of risk factor measurements. In temporal analyses, where smooth functions of time are commonly used to control for confounding, concerns relate to the adequacy of control and the possibility that abrupt changes in risk might be systematically related to pollution levels. Spatial-temporal approaches are subject to challenges faced in both spatial and temporal analyses.
Each approach faces different challenges with respect to the likely sources of confounding and the ability to control for that confounding because of differences in the type, availability, and quality of information required. Thoughtful consideration of these differences should help investigators select the analytic approach that best promotes the validity of their research.
Journal of epidemiology and community health 03/2009; 63(6):500-4. DOI:10.1136/jech.2008.080499 · 3.50 Impact Factor