Estimating Causal Effects of Particulate Matter Regulation on Mortality.

BACKGROUND: Estimating the causal effect of pollution on human health is integral for evaluating returns to pollution regulation, yet separating out confounding factors remains a perennial challenge. METHODS: We use a quasi-experimental design to investigate the causal relationship between regulation of particulate matter smaller than 2.5 micrograms per cubic meter (PM2.5) and mortality among those 65 years of age and older. We exploit regulatory changes in the Clean Air Act Amendments (CAAA). Regulation in 2005 impacted areas of the United States differentially based on pre-regulation air quality levels for PM2.5. We use county-level mortality data, extracted from claims data managed by the Centers for Medicare & Medicaid Services, merged to county-level average PM2.5 readings and attainment status as classified by the Environmental Protection Agency. RESULTS: Based on estimates from log-linear difference-in-differences models, our results indicate after the CAAA designation for PM2.5 in 2005, PM2.5 levels decreased 1.59 micrograms per cubic meter (95% CI = 1.39, 1.80) and mortality rates among those 65 and older decreased by 0.93% (95% CI = 0.10%, 1.77%) in nonattainment counties, relative to attainment ones. Results are robust to a series of alternate models, including nearest-neighbor matching based on propensity score estimates. CONCLUSION: This analysis suggests large health returns to the 2005 PM2.5 designations, and provides evidence of a causal association between pollution and mortality among the Medicare population.

Race and Remdesivir: Examination of Clinical Outcomes in a Racially and Ethnically Diverse Cohort in New York City.

Objective: To compare clinical characteristics and examine in-hospital length of stay (LOS) differences for COVID-19 patients who received remdesivir, by race or ethnicity. Design: Retrospective descriptive analysis comparing cumulative LOS as a proxy of recovery time. Setting: A large academic medical center serving a minoritized community in Northern Manhattan, New York City. Participants: Inpatients (N=1024) who received remdesivir from March 30, 2020-April 20, 2021. Methods: We conducted descriptive analyses among patients who received remdesivir. Patients were described by proxies of social determinants of health (SDOH): race and ethnicity, residence, insurance coverage, and clinical characteristics. We calculated median hospital LOS as the cumulative incidence of hospitalized patients who were discharged alive, and tested differences between groups by using the Gray test. Patients who died or were discharged to hospice were censored at 29 days. Main Outcome Measures: The primary outcome was hospital LOS. The secondary outcome was in-hospital mortality. Results: Median LOS was 11.9 days (95% CI, 10.8-13.2) overall, with Black patients having the shortest (10.0 days, 95% CI, 8.0-13.2) and Asian patients having the longest (16.2 days, 95% CI, 8.3-27.2) LOS. A total of 214 patients (21%) died or were discharged to hospice, ranging from 16.5% to 23.7% of patients who identified as Black and Other (multiracial, biracial, declined), respectively. Conclusions: COVID-19 has disproportionately burdened communities of color. We observed no difference in median LOS between racial or ethnic groups, which supports the notion that the heterogeneous effect of remdesivir in the literature may be explained in part by underrecruitment or participation of Black, Hispanic, and Asian patients in clinical trials.

Costs of healthcare- and community-associated infections with antimicrobial-resistant versus antimicrobial-susceptible organisms.

OBJECTIVE: We compared differences in the hospital charges, length of hospital stay, and mortality between patients with healthcare- and community-associated bloodstream infections, urinary tract infections, and pneumonia due to antimicrobial-resistant versus -susceptible bacterial strains. METHODS: A retrospective analysis of an electronic database compiled from laboratory, pharmacy, surgery, financial, and patient location and device utilization sources was undertaken on 5699 inpatients who developed healthcare- or community-associated infections between 2006 and 2008 from 4 hospitals (1 community, 1 pediatric, 2 tertiary/quaternary care) in Manhattan. The main outcome measures were hospital charges, length of stay, and mortality among patients with antimicrobial-resistant and -susceptible infections caused by Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. RESULTS: Controlling for multiple confounders using linear regression and nearest neighbor matching based on propensity score estimates, resistant healthcare- and community-associated infections, when compared with susceptible strains of the same organism, were associated with significantly higher charges ($15,626; confidence interval [CI], $4339-$26,913 and $25,573; CI, $9331-$41,816, respectively) and longer hospital stays for community-associated infections (3.3; CI, 1.5-5.4). Patients with resistant healthcare-associated infections also had a significantly higher death rate (0.04; CI, 0.01-0.08). CONCLUSIONS: With careful matching of patients infected with the same organism, antimicrobial resistance was associated with higher charges, length of stay, and death rates. The difference in estimates after accounting for censoring for death highlight divergent social and hospital incentives in reducing patient risk for antimicrobial resistant infections.

What about tocilizumab? A retrospective study from a NYC Hospital during the COVID-19 outbreak.

BACKGROUND: Tocilizumab, an interleukin-6 receptor blocker, has been used in the inflammatory phase of COVID-19, but its impact independent of corticosteroids remains unclear in patients with severe disease. METHODS: In this retrospective analysis of patients with COVID-19 admitted between March 2 and April 14, 2020 to a large academic medical center in New York City, we describe outcomes associated with tocilizumab 400 mg (without methylprednisolone) compared to a propensity-matched control. The primary endpoints were change in a 7-point ordinal scale of oxygenation and ventilator free survival, both at days 14 and 28. Secondary endpoints include incidence of bacterial superinfections and gastrointestinal perforation. Primary outcomes were evaluated using t-test. RESULTS: We identified 33 patients who received tocilizumab and matched 74 controls based on demographics and health measures upon admission. After adjusting for illness severity and baseline ordinal scale, we failed to find evidence of an improvement in hypoxemia based on an ordinal scale at hospital day 14 in the tocilizumab group (OR 2.2; 95% CI, 0.7-6.5; p = 0.157) or day 28 (OR 1.1; 95% CI, 0.4-3.6; p = 0.82). There also was no evidence of an improvement in ventilator-free survival at day 14 (OR 0.8; 95% CI, 0.18-3.5; p = 0.75) or day 28 (OR 1.1; 95% CI, 0.1-1.8; p = 0.23). There was no increase in secondary bacterial infection rates in the tocilizumab group compared to controls (OR 0.37; 95% CI, 0.09-1.53; p = 0.168). CONCLUSIONS: There was no evidence to support an improvement in hypoxemia or ventilator-free survival with use of tocilizumab 400 mg in the absence of corticosteroids. No increase in secondary bacterial infections was observed in the group receiving tocilizumab.

Association of groundwater constituents with topography and distance to unconventional gas wells in NE Pennsylvania.

Recently we reported an association of certain diseases with unconventional gas development (UGD). The purpose of this study is to examine UGD's possible impacts on groundwater quality in northeastern Pennsylvania. In this study, we compared our groundwater data (Columbia 58 samples) with those published data from Cabot (1701 samples) and Duke University (150 samples). For each dataset, proportions of samples with elevated levels of dissolved constituents were compared among four groups, identified as upland far (i.e. ≥1km to the nearest UGD gas well), upland near (<1km), valley far (≥1km), and valley near (<1km) groups. The Columbia data do not show statistically significant differences among the 4 groups, probably due to the limited number of samples. In Duke samples, Ca and CI levels are significantly higher in the valley near group than in the valley far group. In the Cabot dataset, methane, Na, and Mn levels are significantly higher in valley far samples than in upland far samples. In valley samples, Ca, Cl, SO4, and Fe are significantly higher in the near group (i.e. <1km) than in the far group. The association of these constituents in valley groundwater with distance is observed for the first time using a large industry dataset. The increase may be caused by enhanced mixing of shallow and deep groundwater in valley, possibly triggered by UGD process. If persistent, these changes indicate potential for further impact on groundwater quality. Therefore, there is an urgent need to conduct more studies to investigate effects of UGD on water quality and possible health outcomes.

Air pollution, health, and socio-economic status: the effect of outdoor air quality on childhood asthma.

This paper estimates the effect of air pollution on child hospitalizations for asthma using naturally occurring seasonal variations in pollution within zip codes. Of the pollutants considered, carbon monoxide (CO) has a significant effect on asthma for children ages 1-18: if 1998 pollution levels were at their 1992 levels, there would be a 5-14% increase in asthma admissions. Also, households respond to information about pollution with avoidance behavior, suggesting it is important to account for these endogenous responses when measuring the effect of pollution on health. Finally, the effect of pollution is greater for children of lower socio-economic status (SES), indicating that pollution is one potential mechanism by which SES affects health.

Long term effects of childhood asthma on adult health.

Childhood asthma is a major chronic condition affecting millions of children in this country, yet little is known about its potential long term consequences. In this paper, we estimate the relationship between childhood asthma and several outcomes as a young adult. To overcome many of the methodological issues plaguing earlier research on this topic, we estimate sibling fixed effect models that correct for measurement error using parental reports of asthma status. In our preferred specification, we find substantial long term impacts of childhood asthma on general health status, obesity, and missed work and school days as a young adult. Broadly, our findings contribute to the growing literature in social sciences on the impacts of early life health conditions on later life health and social outcomes and suggest early treatment of asthma may have long-run benefits on young adult health and socioeconomic outcomes.