Neighborhood mobility, air pollution levels impact COVID-19 hospitalization risk
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Key takeaways:
- COVID-19 hospitalization risk decreased in areas with less air pollution and more mobility.
- Risk for hospitalization with built environment factors differed in non-Hispanic white and Hispanic/Latinx individuals.
Individuals with COVID-19 living in neighborhoods with high walkability and bikeability and less air pollution experienced fewer hospitalizations vs. areas with low mobility and more pollution, according to results published in PLoS ONE.
“These findings are important for clinicians to be aware of because they can affect how we talk with our patients about health,” Sarah E. Rowan, MD, associate director of HIV and viral hepatitis prevention at the Public Health Institute at Denver Health and associate professor of medicine in the division of infectious diseases at the University of Colorado School of Medicine, told Healio. “As we talk about modifiable risk factors, we always emphasize healthy eating, exercise and quitting smoking. Understanding that our patients are affected by their environment in ways that are typically out of their immediate control is critical for putting our recommendations in context.
“On the population level, we as clinicians can use this data to advocate for better air quality, both indoor and outdoor, and more walkable and bikeable communities,” Rowan added. “In terms of economic implications, health care systems could possibly see fewer hospitalizations and lower costs if our communities moved in these directions as well.”
Rowan, Alessandro Rigolon, PhD, associate professor in the department of city and metropolitan planning at The University of Utah, and colleagues assessed 18,042 individuals (median age, 43 years; 58.2% women) residing in the Denver metropolitan area who received a positive COVID-19 test between May and December 2020 to determine if there is a relationship between various neighborhood built environment factors and COVID-19 hospitalizations.
This study considered variables within four different neighborhood built characteristic categories: population density and crowding, environmental hazards, environmental amenities and mobility options.
To make sure spatial dependence, demographic characteristics (age, gender, race/ethnicity, BMI tobacco smoking) and comorbidity conditions (diabetes, hypertension, chronic kidney disease, chronic lung disease) were accounted for in analysis, researchers employed Poisson models with robust standard errors.
Hospitalization demographics
Of the total cohort, hospitalization for COVID-19 occurred in 5,239 individuals (29.03%). Those hospitalized tended to be older (median age, 50 years vs. 41 years) and more likely to be men (44.3% vs. 40.7%). There were also differences among race/ethnicity, including among a cohort the researchers referred to as Hispanic/Latinx (45.2% vs. 39.5%) and among non-Hispanic Black individuals (9.9% vs. 5.5%).
Individuals admitted vs. not admitted to a hospital also had greater median BMIs (30 kg/m2 vs. 28.6 kg/m2) and higher percentages of individuals with diabetes, hypertension, chronic kidney disease and chronic lung disease.
“These findings reinforce what clinicians already knew about some of the individual risk factors for COVID-19 hospitalizations,” Rigolon told Healio. “Even when controlling for environmental exposures, being older, being a male, having higher [BMI], having hypertension, having chronic kidney disease and having chronic lung disease increase the risk of hospitalization for those with COVID-19. These findings emerged for people who were not vaccinated, as they reflect data from 2020.”
Neighborhood built characteristics
In the evaluation of factors within the density and crowding category, researchers observed that more individuals who lived in a multifamily building reported to the hospital compared with individuals residing in a single-family unit (incidence rate ratio [IRR] = 1.142; 95% CI, 1.075-1.213).
“Living in a population-dense area was not a risk factor for hospitalization, but living in a multifamily building was,” Rowan told Healio. “We were not able to control for indoor air quality, but this could be a factor in explaining why living in a multifamily building was a risk factor for hospitalization.”
A heightened risk for hospital admission also occurred among individuals who resided in areas with elevated levels of particulate matter at a 2.5 µm scale (PM2.5; IRR = 1.19; 95% CI, 1.151-1.23).
In terms of environmental amenities, researchers found more occurrences of hospitalizations among those who lived in close proximity (within a half mile) to a park vs. further away (IRR = 1.056; 95% CI, 1.002-1.115), which Rigolon told Healio was surprising.
“We expected to find that individuals living in greener neighborhoods (with more greenery, closer to parks) would have a lower risk of hospitalization, [but] they did not when controlling for individual and built environment factors,” Rigolon said.
Hospital occurrences dropped when neighborhoods had increased walkability (IRR = 0.957; 95% CI, 0.919-0.996) and bikeability (IRR = 0.919; 95% CI, 0.883-0.956) scores.
“Our findings add some risk factors related to the built environment, and clinicians need to be aware that patients living in neighborhoods with higher air pollution and lower walkability and bikeability might be at higher risk of hospitalization from COVID-19,” Rigolon told Healio.
Racial/ethnic disparities
To compare differences in the relationship between COVID-19 hospitalization and built environment factors by race/ethnicity, researchers evaluated non-Hispanic white individuals (47.2%) and Hispanic/Latinx individuals (41.1%) separately.
In this analysis, Rigolon and Rowan unexpectedly found that the greater risk for COVID-19 hospitalization with elevated levels of PM2.5 was more pronounced among Hispanic/Latinx individuals (IRR = 1.347; 95% CI, 1.289-1.407) than non-Hispanic white individuals (IRR = 1.087; 95% CI, 1.041-1.136).
“Those associations were much stronger for Hispanic/Latino individuals, which is concerning given existing health disparities in the U.S.,” Rigolon said.
Additionally, researchers found that Hispanic/Latinx individuals living in areas with low walkability had an increased risk for hospitalization, whereas this link was not observed in non-Hispanic white individuals.
On the other hand, the greater risk for COVID-19 hospitalization associated with living in a multifamily unit appeared more pronounced among non-Hispanic white individuals than Hispanic/Latinx individuals (IRR = 1.265; 95% CI, 1.143-1.401 vs. 1.126; 95% CI, 1.017-1.247).
Further, non-Hispanic white individuals with COVID-19 faced a heightened risk for hospitalization when they lived in neighborhoods with low bikeability, more access to public transit, more overcrowded units and a distance of more than half a mile from a park, whereas this was not found for Hispanic/Latinx individuals.
“Racial/ethnic disparities in COVID-19 outcomes were part of the motivation for our study,” Rigolon told Healio. “We found that the neighborhood built environment has disparate effects on non-Hispanic white and Hispanic/Latino patients. Those are important findings that warrant further investigation to help address systemic health disparities.”
Future studies
When asked about future studies, Rigolon and Rowan told Healio researchers could assess the relationship between COVID-19 hospitalization and built environment factors in different regions of the U.S.
“Repeating this study about COVID outcomes using 2020 data from other cities would be really insightful,” Rowan said.
Rigolon and Rowan also said this research could be continued by evaluating different respiratory viruses.
“We expect future studies to focus on the built environment’s effects on other respiratory viruses, like the flu,” Rigolon told Healio.
“The amount of testing for SARS-CoV-2 was unique — people with mild symptoms or exposures were testing with lab-based tests in 2020, which allowed us access to a large amount of information about this virus and its range of health impacts,” Rowan added. “It would be difficult to repeat this now that people typically use home tests for COVID-19, and with something like flu, [people] often don’t test if symptoms are mild. In a bad flu season though, it could be done.”
For more information:
Alessandro Rigolon, PhD, can be reached at alessandro.rigolon@utah.edu.
Sarah E. Rowan, MD, can be reached at sarah.rowan@dhha.org.