VCBART: Bayesian trees for varying coefficients

Many studies have reported associations between later-life cognition and socioeconomic position in childhood, young adulthood, and mid-life. However, the vast majority of these studies are unable to quantify how these associations vary over time and with respect to several demographic factors. Varying coefficient (VC) models, which treat the covariate effects in a linear model as nonparametric functions of additional effect modifiers, offer an appealing way to overcome these limitations. Unfortunately, state-of-the-art VC modeling methods require computationally prohibitive parameter tuning or make restrictive assumptions about the functional form of the covariate effects. In response, we propose VCBART, which estimates the covariate effects in a VC model using Bayesian Additive Regression Trees. With simple default hyperparameter settings, VCBART outperforms existing methods in terms of covariate effect estimation and prediction. Using VCBART, we predict the cognitive trajectories of 4,167 subjects from the Health and Retirement Study using multiple measures of socioeconomic position and physical health. We find that socioeconomic position in childhood and young adulthood have small effects that do not vary with age. In contrast, the effects of measures of mid-life physical health tend to vary with respect to age, race, and marital status. An R package implementing VC-BART is available at https://github.com/skdeshpande91/VCBAR

An analysis of the dependence of saccadic latency on target position and target characteristics in human subjects

BACKGROUND: Predictions from conduction velocity data for primate retinal ganglion cell axons indicate that the conduction time to the lateral geniculate nucleus for stimulation of peripheral retina should be no longer than for stimulation of central retina. On this basis, the latency of saccadic eye movements should not increase for more peripherally located targets. However, previous studies have reported relatively very large increases, which has the implication of a very considerable increase in central processing time for the saccade-generating system. RESULTS: In order to resolve this paradox, we have undertaken an extended series of experiments in which saccadic eye movements were recorded by electro-oculography in response to targets presented in the horizontal meridian in normal young subjects. For stationary or moving targets of either normal beam intensity or reduced red intensity, with the direction of gaze either straight ahead with respect to the head or directed eccentrically, the saccadic latency was shown to remain invariant with respect to a wide range of target angular displacements. CONCLUSIONS: These results indicate that, irrespective of the angular displacement of the target, the direction of gaze or the target intensity, the saccade-generating system operates with a constant generation time

Advancing Understanding of Chemical Exposures and Maternal-child Health Through the U.S. Environmental Influences on Child Health Outcomes (ECHO) Program: A Scoping Review.

PURPOSE OF REVIEW: Environmental chemical exposures may disrupt child development, with long-lasting health impacts. To date, U.S. studies of early environmental exposures have been limited in size and diversity, hindering power and generalizability. With harmonized data from over 60,000 participants representing 69 pregnancy cohorts, the National Institutes of Healths Environmental influences on Child Health Outcomes (ECHO) Program is the largest study of U.S. childrens health. Here, we: (1) review ECHO-wide studies of chemical exposures and maternal-child health; and (2) outline opportunities for future research using ECHO data. RECENT FINDINGS: As of early 2024, in addition to over 200 single-cohort (or award) papers on chemical exposures supported by ECHO, ten collaborative multi-cohort papers have been made possible by ECHO data harmonization and new data collection. Multi-cohort papers have examined prenatal exposure to per- and polyfluoroalkyl substances (PFAS), phthalates, phenols and parabens, organophosphate esters (OPEs), metals, melamine and aromatic amines, and emerging contaminants. They have primarily focused on describing patterns of maternal exposure or examining associations with maternal and infant outcomes; fewer studies have examined later child outcomes (e.g., autism) although follow up of enrolled ECHO children continues. The NICHDs Data and Specimen Hub (DASH) database houses extensive ECHO data including over 470,000 chemical assay results and complementary data on priority outcome areas (pre, peri-, and postnatal, airway, obesity, neurodevelopment, and positive health), making it a rich resource for future analyses. ECHOs extensive data repository, including biomarkers of chemical exposures, can be used to advance our understanding of environmental influences on childrens health. Although few published studies have capitalized on these unique harmonized data to date, many analyses are underway with data now widely available

Demand for Self-Managed Online Telemedicine Abortion in the United States During the Coronavirus Disease 2019 (COVID-19) Pandemic.

For many in the United States, abortion care is already difficult to access,1 and the coronavirus disease 2019 (COVID-19) pandemic has created yet more potential barriers—including infection risk at clinics and state policies limiting in-clinic services. The severity of these state policies varies, but, in the most extreme case, Texas effectively suspended all abortions for approximately 4 weeks.2 As a result, people may increasingly be seeking self-managed abortion outside the formal health care system. Using data from Aid Access, the sole online abortion telemedicine service in the United States, we assessed whether demand for self-managed medication abortion increased as in-clinic access became more challenging

Prognostic Role of Serum Chloride Levels in Acute Decompensated Heart Failure

BACKGROUND: Acute decompensated heart failure (ADHF) can be complicated by electrolyte abnormalities, but the major focus has been concentrated on the clinical significance of serum sodium levels

Austin COVID-19 transmission estimates and healthcare projections

To support public health decision-making and healthcare planning, we developed a model for the five-county Austin-Round Rock Metropolitan Statistical Area (henceforth Austin) that can provide real-time estimates of the prevalence and transmission rate of COVID-19 and project healthcare needs into the future. The model incorporates key epidemiological characteristics of the disease, demographic information for Austin, and local mobility data from anonymized cell phone traces. It uses daily COVID-19 hospitalization data to estimate the changing transmission rate and prevalence of disease. The framework can be readily applied to provide pandemic situational awareness and short-term healthcare projections in other cities around the US. In this report, we use COVID-19 hospitalization data for Austin from March 13 to July 14, 2020 to estimate the state of the pandemic in early July and project hospitalizations through early August of 2020. The projections are based on multiple assumptions about the age-specific severity of COVID-19 and the role of asymptomatic infections in the transmission of the virus. These graphs below do not present the full range of uncertainty for the city of Austin, but are intended to provide basic insight into the changing risks of COVID-19 transmission and healthcare surges in Austin. Our estimates suggest that the pandemic slowed considerably during the March 24-May 1, 2020 stay-home order and reached its lowest transmission rate in mid April. As Texas began relaxing social distancing measures in early May, transmission picked up and continued to increase through mid June. The recent decrease in transmission may have stemmed from mid-June tightening of restrictions and an increase in cautionary messaging. Our projections suggest that, if the pandemic continues to spread at the rate estimated from the second week of July, COVID-19 hospitalizations and/or ICU demands could exceed local capacity in early August. We are posting these results prior to peer review to provide intuition for both policy makers and the public regarding both the immediate threat of COVID-19 and the extent to which continued social distancing, transmission-reducing precautions such as keeping physical distance, wearing cloth face coverings and staying isolated when symptomatic, can mitigate that threat. As new hospitalization data become available, we will provide updated estimates and projections on the UT COVID-19 Modeling Consortium's Austin COVID-19 Dashboard.Integrative Biolog

Blood pressure vs altitude in hypertensive and non-hypertensive himalayan trekkers

Introduction: Determine blood pressure (BP) response to changes in altitude in Himalayan trekkers with and without hypertension (HTN). Methods: BP was measured in Lukla (2800m), Namche (3400m), and either Pheriche or Dingboche (4400m) on ascent and descent. Hypertensive subjects were defined by self-reported diagnosis of HTN. Results: Trekkers had HTN (H, n=60) or no HTN (NH, n=604). Of those with HTN, 50 (83%) took one or more BP medications including ACEIs/ARBs (n=35, 48%), Ca++ channel blockers (n=15, 22%), beta-blockers (n=9, 13%), thiazide diuretics (n=7, 10%), and others (n=5, 7%). At 2800m, systolic BP (SBP) and diastolic BP (DBP) were greater in the H group than in the NH group [mean SBP= 151mmHg (95% CI 145.4-155.7) vs 127mmHg (95% CI 125.5 128.0); mean DBP=88mmHg (95% CI 85.1-91.7) vs 80mmHg (95% CI 79.3-80.8)] and remained higher at both 3400m [mean SBP=150mmHg (95% CI 143.7-156.9) vs 127mmHg (95% CI 125.8-128.5); mean DBP=88mmHg (95% CI 84.3-90.8) vs 82mmHg (95% CI 80.7-82.5)] and 4400m [mean SBP=144mmHg (95% CI 136.7-151.7) vs 128mmHg (95% CI 126.4-129.5); mean DBP=87mmHg (95% CI 83.2-91.7) vs 82mmHg (95% CI 81.3-83.2)]. Between 2800m and 3400m, BP increased in 37% of trekkers, decreased in 25%, and did not change in 38%; from 3400m to 4400m, BP increased in 35% of trekkers, decreased in 26%, and did not change in 40%. Prevalence of severe hypertension (BP\u3e180/120mmHg) was similar across altitudes but higher in the H group (9%; 10%; 8% vs 0.7%; 0.6%, 0.3%) at 2800m, 3400m, and 4400m, respectively. No subjects reported symptoms of hypertensive emergency (chest pain, stroke, etc.). Conclusion: Blood pressure response to altitude is variable. High prevalence of severe hypertension in hypertensive trekkers warrants further study regarding BP control at high altitude

Texas Trauma Service Area (TSA) COVID-19 transmission estimates and healthcare projections: August 25, 2020

To support public health decision-making and healthcare planning, we developed a model that can provide real-time estimates of the prevalence and transmission rate of COVID-19 and project healthcare needs into the future for each of the 22 Trauma Service Areas (TSA) in Texas. The model incorporates key epidemiological characteristics of the disease, demographic information for each TSA, and local mobility data from anonymized cell phone traces. It uses daily COVID-19 hospitalization data to estimate the changing transmission rate and prevalence of disease. The framework can be readily applied to provide pandemic situational awareness and short-term healthcare projections in other cities around the US. In this report, we use COVID-19 hospitalization data for each TSA from April 11 to August 11, 2020 to estimate the state of the pandemic in late July and project hospitalizations through early September of 2020. The data were provided by Texas DSHS through daily and weekly reports as summarized in the Texas COVID-19 Data Resource by Texas 2036[1]. We note that the data are not available before April 11th and that the projections are based on multiple assumptions about the age-specific severity of COVID-19 and the role of asymptomatic infections in the transmission of the virus. These graphs below do not present the full range of uncertainty, but are intended to provide basic insight into the changing risks of COVID-19 transmission and healthcare surges in each TSA. Our estimates suggest that every TSA has experienced a recent surge in cases, hospitalizations, and mortality, with transmission starting to rise in early May. Transmission rates have declined since our July 22nd report, with no regions having over a 50% chance of a growing epidemic. While COVID-19 is still straining healthcare systems across the state, the risks of overwhelming surges have diminished. In all TSAs, the risk of exceeding general hospital capacity is now below 10%; only four TSAs have over a 10% risk of exceeding baseline (non-surge) ICU bed capacity: Laredo (20.6%), Abilene (19%), Wichita Falls (16.6%), and Amarillo (10.6%). We are posting these results prior to peer review to provide intuition for both policy makers and the public regarding both the immediate threat of COVID-19 and the extent to which continued social distancing, transmission-reducing precautions such as keeping physical distance, wearing cloth face coverings and staying isolated when symptomatic, can mitigate that threat. Note, this report replaces a report posted on August 19th, 2020. We recently identified inconsistencies in the reporting of hospital admissions across TSAs since July 21, 2020. Thus, we revised our estimates using only COVID-19 hospital census rather than both COVID-19 hospital admissions and census data starting on July 22, 2020.Integrative Biolog