Alemtuzumab for multiple sclerosis: Long term follow-up in a multi-centre cohort

Background:

Alemtuzumab has recently been approved for treatment of relapsing MS, but concerns remain about its use since long-term studies of adverse events remain limited. Furthermore, a clear understanding of its application and durability of effect in clinical practice has yet to evolve.

Objectives:

To investigate long-term efficacy and safety outcomes in a multicentre cohort of patients treated with alemtuzumab.

Methods:

Patients treated from 2000 and followed-up at three regional centres were identified. Baseline and prospective data were obtained and validated by clinical record review.

Results:

One hundred patients were identified with a mean follow-up of 6.1 years (range 1–13). Forty patients were retreated with at least one further treatment cycle. Annualized relapse rates fell from 2.1 to 0.2 ( p<0.0001) post-treatment and were sustained for up to eight years of follow-up. Mean change in EDSS score was +0.14. Forty-seven patients developed secondary autoimmunity.

Conclusion:

Observed reduction in relapse rates reflected those reported in clinical trials, but we were unable to corroborate previous observations of disability reversal. 40% of patients required additional treatment cycles. Autoimmune adverse events were common, occurring at a higher rate than previously reported, but were largely predictable, and could be managed effectively within a rigorous monitoring regime.

A Prospective Cohort Study of COVID-19 Vaccination, SARS-CoV-2 Infection, and Fertility

Some reproductive-aged individuals remain unvaccinated against coronavirus disease 2019 (COVID-19) because of concerns about potential adverse effects on fertility. Using data from an internet-based preconception cohort study, we examined the associations of COVID-19 vaccination and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with fertility among couples trying to conceive spontaneously. We enrolled 2,126 self-identified female participants aged 21-45 year residing in the United States or Canada during December 2020-September 2021 and followed them through November 2021. Participants completed questionnaires every 8 weeks on sociodemographics, lifestyle, medical factors, and partner information. We fit proportional probabilities regression models to estimate associations between self-reported COVID-19 vaccination and SARS-CoV-2 infection in both partners with fecundability (i.e., the per-cycle probability of conception), adjusting for potential confounders. COVID-19 vaccination was not appreciably associated with fecundability in either partner (female fecundability ratio (FR) = 1.08, 95% confidence interval (CI): 0.95, 1.23; male FR = 0.95, 95% CI: 0.83, 1.10). Female SARS-CoV-2 infection was not strongly associated with fecundability (FR = 1.07, 95% CI: 0.87, 1.31). Male infection was associated with a transient reduction in fecundability (for infection within 60 days, FR = 0.82, 95% CI: 0.47, 1.45; for infection after 60 days, FR = 1.16, 95% CI: 0.92, 1.47). These findings indicate that male SARS-CoV-2 infection may be associated with a short-term decline in fertility and that COVID-19 vaccination does not impair fertility in either partner.

Unconventional natural gas development and pediatric asthma hospitalizations in Pennsylvania

BACKGROUND

Pediatric asthma is a common chronic condition that can be exacerbated by environmental exposures, and unconventional natural gas development (UNGD) has been associated with decreased community air quality. This study aims to quantify the association between UNGD and pediatric asthma hospitalizations.

METHODS

We compare pediatric asthma hospitalizations among zip codes with and without exposure to UNGD between 2003 and 2014 using a difference-in-differences panel analysis. Our UNGD exposure metrics include cumulative and contemporaneous drilling as well as reported air emissions by site.

RESULTS

We observed consistently elevated odds of hospitalizations in the top tertile of pediatric patients exposed to unconventional drilling compared with their unexposed peers. During the same quarter a well was drilled, we find a 25% increase (95% CI: 1.07, 1.47) in the odds of being hospitalized for asthma. Ever-establishment of an UNGD well within a zip code was associated with a 1.19 (95% CI: 1.04, 1.36) increased odds of a pediatric asthma hospitalization. Our results further demonstrate that increasing specific air emissions from UNGD sites are associated with increased risks of pediatric asthma hospitalizations (e.g. 2,2,4-trimethylpentane, formaldehyde, x-hexane). These results hold across multiple age groups and sensitivity analyses.

CONCLUSIONS

Community-level UNGD exposure metrics were associated with increased odds of pediatric asthma-related hospitalization among young children and adolescents. This study provides evidence that additional regulations may be necessary to protect children's respiratory health from UNGD activities.

Associations between Residential Proximity to Oil and Gas Drilling and Term Birth Weight and Small-for-Gestational-Age Infants in Texas: A Difference-in-Differences Analysis

BACKGROUND

Oil and natural gas extraction may produce environmental pollution at levels that affect reproductive health of nearby populations. Available studies have primarily focused on unconventional gas drilling and have not accounted for local population changes that can coincide with drilling activity.

OBJECTIVE

Our study sought to examine associations between residential proximity to oil and gas drilling and adverse term birth outcomes using a difference-in-differences study design.

METHODS

We created a retrospective population-based term birth cohort in Texas between 1996 and 2009 composed of mother-infant dyads (n=2,598,025) living <10km from an oil or gas site. We implemented a difference-in-differences approach to estimate associations between drilling activities and infant health: term birth weight and term small for gestational age (SGA). Using linear and logistic regression, we modeled interactions between births before (unexposed) or during (exposed) drilling activity and residential proximity near (0-1, 1-2, or 2-3km) or far (3-10km) from an active or future drilling site, adjusting for individual- and neighborhood-level characteristics.

RESULTS

The adjusted mean difference in term birth weight for mothers living 0-1 vs. 3-10km from a current or future drilling site was -7.3g [95% confidence interval (CI): -11.6, -3.0] for births during active vs. future drilling. The corresponding adjusted odds ratio for SGA was 1.02 (95% CI: 0.98, 1.06). Negative associations with term birth weight were observed for the 1-2 and 2-3km near groups, and no consistent differences were identified by type of drilling activity. Larger, though imprecise, adverse associations were found for infants born to Hispanic women, women with the lowest educational attainment, and women living in cities.

CONCLUSIONS

Residing near oil and gas drilling sites during pregnancy was associated with a small reduction in term birth weight but not SGA, with some evidence of environmental injustices. Additional work is needed to investigate specific drilling-related exposures that might explain these associations. https://doi.org/10.1289/EHP7678.

Acute myocardial infarction associated with unconventional natural gas development: A natural experiment

BACKGROUND

Whereas it is plausible that unconventional natural gas development (UNGD) may adversely affect cardiovascular health, little is currently known. We investigate whether UNGD is associated with acute myocardial infarction (AMI).

METHODS

In this observational study leveraging the natural experiment generated by New York's ban on hydraulic fracturing, we analyzed the relationship between age- and sex-specific county-level AMI hospitalization and mortality rates and three UNGD drilling measures. This longitudinal panel analysis compares Pennsylvania and New York counties on the Marcellus Shale observed over 2005-2014 (N = 2840 county-year-quarters).

RESULTS

A hundred cumulative wells is associated with 0.26 more hospitalizations per 10,000 males 45-54y.o. (95% CI 0.07,0.46), 0.40 more hospitalizations per 10,000 males 65-74y.o. (95% CI 0.09,0.71), 0.47 more hospitalizations per 10,000 females 65-74y.o. (95% CI 0.18,0.77) and 1.11 more hospitalizations per 10,000 females 75y.o.+ (95% CI 0.39,1.82), translating into 1.4-2.8% increases. One additional well per square mile is associated with 2.63 more hospitalizations per 10,000 males 45-54y.o. (95% CI 0.67,4.59) and 9.7 hospitalizations per 10,000 females 75y.o.+ (95% CI 1.92,17.42), 25.8% and 24.2% increases, respectively. As for mortality rates, a hundred cumulative wells is associated with an increase of 0.09 deaths per 10,000 males 45-54y.o. (95% CI 0.02,0.16), a 5.3% increase.

CONCLUSIONS

Cumulative UNGD is associated with increased AMI hospitalization rates among middle-aged men, older men and older women as well as with increased AMI mortality among middle-aged men. Our findings lend support for increased awareness about cardiovascular risks of UNGD and scaled-up AMI prevention as well as suggest that bans on hydraulic fracturing can be protective for public health.

Air pollution and fecundability: Results from a Danish preconception cohort study

BACKGROUND

Animal and epidemiologic studies indicate that air pollution may adversely affect fertility. Epidemiologic studies have been restricted largely to couples undergoing fertility treatment or have retrospectively ascertained time-to-pregnancy among pregnant women.

OBJECTIVES

We examined the association between residential ambient air pollution and fecundability, the per-cycle probability of conception, in a large preconception cohort of Danish pregnancy planners.

METHODS

During 2007-2018, we used the Internet to recruit and follow women who were trying to conceive without the use of fertility treatment. Participants completed an online baseline questionnaire eliciting socio-demographic characteristics, lifestyle factors, and medical and reproductive histories and follow-up questionnaires every 8 weeks to ascertain pregnancy status. We determined concentrations of ambient nitrogen oxides (NOx ), nitrogen dioxide (NO2 ), carbon monoxide (CO), ozone (O3 ), particulate matter <2.5 µm (PM2.5 ) and <10 µm (PM10 ), and sulphur dioxide (SO2 ) at each participant's residential address. We calculated average exposure during the year before baseline, during each menstrual cycle over follow-up and during the entire pregnancy attempt time. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders and co-pollutants. The analysis was restricted to the 10,183 participants who were trying to conceive for <12 cycles at study entry whose addresses could be geocoded.

RESULTS

During 12 months of follow-up, 73% of participants conceived. Higher concentrations of PM2.5 and PM10 were associated with small reductions in fecundability. For example, the FRs for a one interquartile range (IQR) increase in PM2.5 (IQR = 3.2 µg/m3 ) and PM10 (IQR = 5.3 µg/m3 ) during each menstrual cycle were 0.93 (95% CI: 0.87, 0.99) and 0.91 (95% CI: 0.84, 0.99), respectively. Other air pollutants were not appreciably associated with fecundability.

CONCLUSIONS

In this preconception cohort study of Danish women, residential exposures to PM2.5 and PM10 were associated with reduced fecundability.

Association Between Neighborhood Disadvantage and Fertility Among Pregnancy Planners in the US

IMPORTANCE

Decades of inequitable policies in the US have yielded disparities in neighborhood quality, and some studies show that living in a socioeconomically disadvantaged neighborhood is associated with worse health outcomes, including reproductive health outcomes. However, no US studies to date have directly examined the association between residence in disadvantaged neighborhoods and fertility.

OBJECTIVE

To examine the association between residence in disadvantaged neighborhoods and fecundability, a sensitive marker of fertility with many health implications.

DESIGN, SETTING, AND PARTICIPANTS

This prospective preconception cohort study used the Pregnancy Study Online, for which baseline data were collected from June 19, 2013, through April 12, 2019. The study included 6356 participants who identified as female, were 21 to 45 years of age, were attempting conception without fertility treatment, and provided a valid residential address in the contiguous US at enrollment.

EXPOSURES

A standardized area deprivation index (ADI) derived at the census block group level applied to each residential address.

MAIN OUTCOMES AND MEASURES

Fecundability, the per-cycle probability of conception, via questionnaires that were completed every 8 weeks for 12 months, until conception or a censoring event. Proportional probabilities models were used to estimate fecundability ratios and 95% CIs for associations between ADI and fecundability. Restricted cubic splines were also implemented to examine nonlinearity. Models were adjusted for demographic characteristics and factors associated with fertility. The study's a priori hypothesis was that higher levels of neighborhood disadvantage would be associated with decreased fecundability.

RESULTS

Among 6356 participants, 3725 pregnancies were observed for 27 427 menstrual cycles of follow-up. The mean (SD) baseline age was 30.0 (4.1) years, and most participants were non-Hispanic White (5297 [83.3%]) and nulliparous (4179 [65.7%]). Comparing the top and bottom deciles of disadvantaged neighborhood status, adjusted fecundability ratios were 0.79 (95% CI, 0.66-0.96) for national-level ADI rankings and 0.77 (95% CI, 0.65-0.92) for within-state ADI rankings. Restricted cubic splines showed some evidence of nonlinearity in the association. Associations were slightly stronger among participants with lower annual incomes (<$50 000).

CONCLUSIONS AND RELEVANCE

In this cohort study, residence in a socioeconomically disadvantaged neighborhood was associated with moderately decreased fecundability. If confirmed in other studies, these results suggest that investments to reduce disadvantaged neighborhood status may yield positive cobenefits for fertility.

Assessing the effectiveness of vehicle emission regulations on improving perinatal health: a population-based accountability study

BACKGROUND

Since the 1990s, extensive regulations to reduce traffic-related air pollution (TRAP) have been implemented, yet the effectiveness of these regulations has not been assessed with respect to improving infant health. In this study, we evaluate how infant health risks associated with maternal residences near highways during pregnancy have changed over time.

METHODS

We created a population-based retrospective birth cohort with geocoded residential addresses in Texan metropolitan areas from 1996 through 2009 (n = 2 259 411). We compared term birthweight (37-42 weeks of gestation) among maternal residences <300 m from a highway (high TRAP exposure) (n = 394 346) and 500-3500 m from a highway (comparison group) (n = 1 865 065). We implemented linear regressions to evaluate interactions between high TRAP exposure and birth year, adjusting for demographics, socioeconomic status and neighbourhood context. In addition, we used propensity score matching to further reduce residual confounding.

RESULTS

From 1996 to 2009, outdoor NO2 decreased by 51.3%, based on regulatory monitoring data in Texas. Among pregnant women who resided in the high TRAP zone during pregnancy, interaction terms between residential location and birth year show that birthweight increased by 1.1 g [95% confidence interval CI): 0.7, 1.5) in unadjusted models and 0.3 g (95% CI: 0.0, 0.6) in matched models. Time-stratified models also show decreasing impacts of living in high TRAP areas on birthweight when comparing infants born in 1996-97 with 2008-09. Sensitivity analyses with alternative exposure and control groups show consistent results.

CONCLUSIONS

Infant health risks associated with maternal residence near highways have reduced over time, paralleling regulatory measures to improve exhaust pipe emissions.

COVID-19 vaccination and menstrual cycle characteristics: A prospective cohort study

We prospectively examined the association between COVID-19 vaccination and menstrual cycle characteristics in an internet-based prospective cohort study. We included a sample of 1,137 participants who enrolled in Pregnancy Study Online (PRESTO), a preconception cohort study of couples trying to conceive, during January 2021-August 2022. Eligible participants were aged 21-45 years, United States or Canadian residents, and trying to conceive without fertility treatment. At baseline and every 8 weeks for up to 12 months, participants completed questionnaires on which they provided information on COVID-19 vaccination and menstrual cycle characteristics, including cycle regularity, cycle length, bleed length, heaviness of bleed, and menstrual pain. We fit generalized estimating equation (GEE) models with a log link function and Poisson distribution to estimate the adjusted risk ratio (RR) for irregular cycles associated with COVID-19 vaccination. We used linear regression with GEE to estimate adjusted mean differences in menstrual cycle length associated with COVID-19 vaccination. We adjusted for sociodemographic, lifestyle, medical and reproductive factors. Participants had 1.1 day longer menstrual cycles after receiving the first dose of COVID-19 vaccine (95 % CI: 0.4, 1.9) and 1.3 day longer cycles after receiving the second dose (95 % CI: 0.2, 2.5). Associations were attenuated at the second cycle post-vaccination. We did not observe strong associations between COVID-19 vaccination and cycle regularity, bleed length, heaviness of bleed, or menstrual pain. In conclusion, COVID-19 vaccination was associated with a ∼1 day temporary increase in menstrual cycle length, but was not appreciably associated with other menstrual cycle characteristics.

Congenital anomalies associated with oil and gas development and resource extraction: a population-based retrospective cohort study in Texas

BACKGROUND

Oil and gas extraction-related activities produce air and water pollution that contains known and suspected teratogens. To date, health impacts of in utero exposure to these activities is largely unknown.

OBJECTIVE

We investigated associations between in utero exposure to oil and gas extraction activity in Texas, one of the highest producers of oil and gas, and congenital anomalies.

METHODS

We created a population-based birth cohort between 1999 and 2009 with full maternal address at delivery and linked to the statewide congenital anomaly surveillance system (n = 2,234,138 births, 86,315 cases). We examined extraction-related exposures using tertiles of inverse distance-squared weighting within 5 km for drilling site count, gas production, oil production, and produced water. In adjusted logistic regression models, we calculated odds of any congenital anomaly and 10 specific organ sites using two comparison groups: 1) 5 km of future drilling sites that are not yet operating (a priori main models), and 2) 5-10 km of an active well.

RESULTS

Using the temporal comparison group, we find increased odds of any congenital anomaly in the highest tertile exposure group for site count (OR: 1.25; 95% CI: 1.21, 1.30), oil production (OR: 1.08; 95% CI: 1.04, 1.12), gas production (1.20; 95% CI: 1.17, 1.23), and produced water (OR: 1.17; 95% CI: 1.14, 1.20). However, associations did not follow a consistent exposure-response pattern across tertiles. Associations are highly attenuated, but still increased, with the spatial comparison group in the highest tertile exposure group. Cardiac and circulatory defects are strongly and consistently associated with all exposure metrics.

SIGNIFICANCE

Increased odds of congenital anomalies, particularly cardiac and circulatory defects, were associated with exposures related to oil and gas extraction in this large population-based study. Future research is needed to confirm findings, examine specific exposure pathways, and identify potential avenues to reduce exposures among local populations.

IMPACT

About 5% of the U.S. population (~17.6 million people) resides within 1.6 km of an active oil or gas extraction site, yet the influence of this industry on population health is not fully understood. In this analysis, we examined associations between oil and gas extraction-related exposures and congenital anomalies by organ site using birth certificate and congenital anomaly surveillance data in Texas (1999-2009). Increased odds of congenital anomalies, particularly cardiac and circulatory defects, were associated with exposures related to oil and gas extraction in this large population-based study. Future research is needed to confirm these findings.

Associations between residential proximity to oil and gas extraction and hypertensive conditions during pregnancy: a difference-in-differences analysis in Texas, 1996-2009

BACKGROUND

Oil and gas extraction produces air pollutants that are associated with increased risks of hypertension. To date, no study has examined residential proximity to oil and gas extraction and hypertensive conditions during pregnancy. This study quantifies associations between residential proximity to oil and gas development on gestational hypertension and eclampsia.

METHODS

We utilized a population-based retrospective birth cohort in Texas (1996-2009), where mothers reside <10 km from an active or future drilling site (n = 2 845 144.) Using full-address data, we linked each maternal residence at delivery to assign exposure and evaluate this exposure with respect to gestational hypertension and eclampsia. In a difference-in-differences framework, we model the interaction between maternal health before (unexposed) or after (exposed) the start of drilling activity (exposed) and residential proximity near (0-1, >1-2 or >2-3 km) or far (≥3-10 km) from an active or future drilling site.

RESULTS

Among pregnant women residing 0-1 km from an active oil or gas extraction site, we estimate 5% increased odds of gestational hypertension [95% confidence interval (CI): 1.00, 1.10] and 26% increased odds of eclampsia (95% CI: 1.05, 1.51) in adjusted models. This association dissipates in the 1- to 3-km buffer zones. In restricted models, we find elevated odds ratios among maternal ages ≤35 years at delivery, maternal non-Hispanic White race, ≥30 lbs gained during pregnancy, nulliparous mothers and maternal educational attainment beyond high school.

CONCLUSIONS

Living within 1 km of an oil or gas extraction site during pregnancy is associated with increased odds of hypertensive conditions during pregnancy.

A population-based cohort study of traffic congestion and infant growth using connected vehicle data

More than 11 million Americans reside within 150 meters of a highway, an area of high air pollution exposure. Traffic congestion further contributes to environmental pollution (e.g., air and noise), but its unique importance for population health is unclear. We hypothesized that degraded environmental quality specifically from traffic congestion has harmful impacts on fetal growth. Using a population-based cohort of births in Texas (2015-2016), we leveraged connected vehicle data to calculate traffic congestion metrics around each maternal address at delivery. Among 579,122 births, we found consistent adverse associations between traffic congestion and reduced term birth weight (8.9 grams), even after accounting for sociodemographic characteristics, typical traffic volume, and diverse environmental coexposures. We estimated that up to 1.2 million pregnancies annually may be exposed to traffic congestion (27% of births in the United States), with ~256,000 in the highest congestion zones. Therefore, improvements to traffic congestion may yield positive cobenefits for infant health.

Optimizing preconception care and interventions for improved population health

There is growing literature indicating that optimal preconception health is associated with improved reproductive, perinatal, and pediatric outcomes. Given that preconception care is recommended for all individuals planning a pregnancy, medical providers and public health practitioners have a unique opportunity to optimize care and improve health outcomes for reproductive-aged individuals. Knowledge of the determinants of preconception health is important for all types of health professionals, including policy makers. Although some evidence-based recommendations have already been implemented, additional research is needed to identify factors associated with favorable health outcomes and to ensure that effective interventions are made in a timely fashion. Given the largely clinical readership of this journal, this piece is primarily focused on clinical care. However, we acknowledge that optimizing preconception health for the entire population at risk of pregnancy requires broadening our strategies to include population-health interventions that consider the larger social systems, structures, and policies that shape individual health outcomes.

Multiple sclerosis: long-term outcomes in ethnic minorities. Analysis of a UK population-based registry

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is most frequent in Caucasian populations. However, studies of MS in other ethnic groups may offer unique insights into genetic and environmental influences on the disease, and data on long-term outcomes in these patients is limited. In this work clinical features and time to disability milestones were investigated in ethnic minority (EM) patients with MS in a UK population and comparisons were made to a Caucasian cohort from the same region.

METHODS

In all, 1949 MS patients (1866 Caucasian, 83 EM) were identified from a regional disease registry. Cox proportional hazards regression was used to analyse the time to Expanded Disability Status Scale (EDSS) 3.0, 4.0 and 6.0.

RESULTS

Ethnic minority patients were younger at disease onset (28.6 years vs. 32.8 years, P = 0.001), and primary progressive MS was less common (EM 4.8%, Caucasian 11.6%, P = 0.03). After correction for clinical variables, ethnicity was associated with time to EDSS 3.0 [EM: hazard ratio (HR) 1.75, P < 0.0001] and 4.0 (HR 1.46, P = 0.03), but not 6.0 (HR 1.5, P = 0.05).

CONCLUSIONS

Ethnic minority patients reach early levels of fixed disability more rapidly than Caucasian patients, but this effect diminishes at later stages of the disease. This has implications for clinical management of these patients.

Changes in Socioeconomic Disparities for Traffic-Related Air Pollution Exposure During Pregnancy Over a 20-Year Period in Texas

Importance

Air pollution presents clear environmental justice issues. However, few studies have specifically examined traffic-related air pollution (TRAP), a source driven by historically racist infrastructure policies, among pregnant individuals, a population susceptible to air pollution effects. How these disparities have changed over time is also unclear but has important policy implications.

Objective

To examine changes in TRAP exposure by sociodemographic characteristics among recorded pregnancies over a 20-year period.

Design, Setting, and Participants

This population-based birth cohort study used descriptive analysis among pregnant individuals in Texas from 1996 to 2016. All pregnant individuals with valid residential address, socioeconomic, and demographic data were included. Individual-level race and ethnicity, education, and maternal birthplace data were extracted from birth certificates and neighborhood-level household income and historical neighborhood disinvestment (ie, redlining) data were assessed via residential addresses. Data analysis occurred between June 2022 and June 2023.

Main Outcomes and Measures

The main outcome, TRAP exposure at residential addresses, was assessed via traffic levels, represented by total and truck-specific vehicle miles traveled (VMT) within 500 m; nitrogen dioxide (no2) concentrations from a spatial-temporal land use regression model (ie, vehicle tailpipe emissions); and National Air Toxic Agency cancer risk index from on-road vehicle emissions. TRAP exposure differences were assessed by sociodemographic indicators over the 1996 to 2016 period.

Results

Among 7 043 598 pregnant people (mean [SD] maternal age, 26.8 [6.1] years) in Texas from 1996 to 2016, 48% identified as Hispanic or Latinx, 4% identified as non-Hispanic Asian or Pacific Islander, 12% identified as non-Hispanic Black, and 36% identified as non-Hispanic White. There were differences in TRAP for pregnant people by all sociodemographic variables examined. The absolute level of these disparities decreased from 1996 to 2016, but the relative level of these disparities increased: for example, in 1996, non-Hispanic Black pregnant individuals were exposed to a mean (SD) 15.3 (4.1) ppb of no2 vs 13.5 (4.4) ppb of no2 for non-Hispanic White pregnant individuals, compared with 2016 levels of 6.7 (2.4) ppb no2 for Black pregnant individuals and 5.2 (2.4) ppb of no2 for White pregnant individuals. Large absolute and relative differences in traffic levels were observed for all sociodemographic characteristics, increasing over time. For example, non-Hispanic Black pregnant individuals were exposed to a mean (SD) of 22 836 (32 844) VMT within 500 m of their homes, compared with 12 478 (22 870) VMT within 500 m of the homes of non-Hispanic White pregnant individuals in 2016, a difference of 83%.

Conclusions and Relevance

This birth cohort study found that while levels of air pollution disparities decreased in absolute terms over the 20 years of the study, relative disparities persisted and large differences in traffic levels remained, requiring renewed policy attention.

A population-based cohort study of electronic tolling, traffic congestion, and adverse birth outcomes

BACKGROUND

Although traffic-related air pollution is largely regulated at the federal level, congestion reduction projects may reduce local traffic and air pollution to levels that create positive co-benefits for population health. In recent years, many urban areas have implemented electronic tolling systems to improve traffic conditions.

OBJECTIVE

Quantify associations between implementing electronic tolling and local changes in traffic and infant health.

METHODS

Using a population-based birth cohort (Texas, 1999-2016), we calculated residential proximity to the nearest tolled road segment within 5 km (n = 625,279) and examined changes in local traffic before and after toll implementation. Using a difference-in-differences design, we compared four markers of adverse birth outcomes (term birth weight, term low birth weight, preterm birth, very preterm birth) among infants from pregnant people residing < 0.5 km from a road segment before and after the tolls were implemented and compared them to a contemporaneous population of pregnant people residing at 2-5 km.

RESULTS

We observed minimal changes in local traffic after the implementation of tolling. Among births within 500 m of a tolled road, we found little evidence of an association between the implementation of tolling and adverse birth outcomes (term birth weight [β: -4.5, 95 % CI: -11.7, 2.6], term low birth weight [OR: 1.00, 95 % CI: 0.89, 1.13], preterm birth [OR: 0.99, 95 % CI: 0.92, 1.05], very preterm birth [OR: 1.00, 95 % CI: 0.84, 1.18]), compared to the contemporaneous control group of births at 2-5 km. In sub-analyses, we found some evidence of a reduced association between toll booth removal and preterm birth (OR: 0.84, 95 % CI: 0.70, 1.01) but not for other outcomes or tolling types.

DISCUSSION

In this large population-based retrospective cohort study of births in Texas, we found little evidence that the implementation of tolling was consistently associated with improvements in local infant health outcomes.

Changes in traffic congestion and air pollution due to major roadway infrastructure improvements in Texas

Traffic-related air pollution (TRAP) is an established health hazard, and roadway construction has the potential to affect TRAP by relieving congestion. The relationship between roadway construction and congestion is of policy importance, but few studies examine it using large samples of construction projects and detailed traffic and air pollution data. We create a dataset of construction projects in Texas and link them to data on air pollution and three variables operationalizing congestion: average annual daily traffic (AADT), AADT per lane, and delay in hours. We use difference-in-difference methods to estimate the effect of widening and intersection improvements on congestion and air pollution. On average over the period during construction, we find that widening increases delay by 42% (95% CI: 30, 56%), but intersection projects do not affect delay. On average and over the first three years post-construction, we find that widening reduces delay by 33% (95% CI: -41, -24%) and reduces NO2 levels within 500 m by 13% (95% CI: -22, -2%), and intersection projects reduce delay by 52% (95% CI: -65, -35%) and reduce NO2 levels within 500 m by 12% (95% CI: -18, -5%). These short-term impacts are relevant for understanding the impact of roadway construction on human health.