Environmental and Social Factors May Explain Regional COVID-19 Disparities

Digital generated image of Covid-19 cell surrounded by plexus structured shell on black background.
Researchers examined the associations between environmental and societal factors and variations in COVID-19-related mortality in those with rheumatic diseases.

Environmental and societal factors could potentially explain differing COVID-19 outcomes by region among individuals with rheumatic diseases, according to study results published in The Lancet Rheumatology.

Researchers conducted an observational study that comprised 14,044 individuals (mean age 54.4±15.6 years; 27.5% men) with rheumatic diseases from 23 countries; most participants were from North America (25.0%; n=3506) and Europe (45.4%; n=6369). Each individual also had a confirmed status of their maximum COVID-19 severity level, which was collected from the COVID-19 Global Rheumatology Alliance registry between March 2020 and August 2021. Societal and environmental factors were obtained using publicly available sources.

The primary endpoint was COVID-19­-related mortality. After controlling for individual risk factors, multivariable logistic regression was employed to assess independent relationships between COVID-19­-related mortality and environmental or societal factors. The researchers used nested mixed-effects models to determine whether environmental or societal factors could explain country-level mortality variations.

Environmental and societal factors found to be significantly associated with higher risk for COVID-19-related mortality were as follows:

  • Fine particulate matter 2.5 microns or fewer (odds ratio [OR] 1.10 per 10 μg/m3; 95% CI, 1.01-1.17; P =.0105);
  • Number of visits to workplaces (OR 1.02 per 1% increase in visit count; 95% CI, 1.00-1.03; P =.032);
  • Number of visits to pharmacies and grocery stores (OR 1.03 per 1% increase in number of visits; 95% CI, 1.02-1.05; P <.0001); and
  • Percentage of the population aged 65 years or older (OR 1.19 per 1% increase; 95% CI, 1.10-1.30; P <.0001).

In contrast, the following were independently associated with lower risk for mortality:

  • Median population age (OR 0.83 per year; 95% CI, 0.78-0.89; P <.0001);
  • Human development index (OR 0.65 per 0.1 increase in index; 95% CI, 0.44-0.96; P =.032);
  • Number of hospital beds (OR 0.94 per 1-bed increase per 1000 people; 95% CI, 0.88-1.00; P =.046);
  • Number of transit station visits (OR 0.96 per 1% visit increase; 95% CI, 0.94-0.98; P <.0001),
  • Follow-up time (OR 0.78 per month; 95% CI, 0.69-0.88; P <.0001); and
  • Containment index (OR 0.83 per 10-unit increase; 95% CI, 0.74-0.93; P =.0018).

Country-level COVID-19­-attributable deaths were sufficiently explained by these factors (intraclass correlation coefficient 1.2%; 95% CI, 0.1-9.5; P =.14).

Limitations of the study include potential provider reporting bias, an inability to study all-cause death, potential misclassification of COVID-19-related death and regional covariates, limited generalizability, and an inability to account for risk factors such as socioeconomic status and vaccination status.

The study authors conclude, “[A]mong people with rheumatic disease, time period of the pandemic wave, exposure to air pollutants, regional socioeconomic factors, availability of and burden on health resources, stringency of government response, and population mobility are associated with death attributed to COVID-19….These findings highlight the importance of environmental and societal factors as potential explanations of the observed regional disparities in COVID-19 outcomes….”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Izadi Z, Gianfrancesco MA, Schmajuk G, et al. Environmental and societal factors associated with COVID-19-related death in people with rheumatic disease: an observational study. Lancet Rheumatol. Published online July 25, 2022. doi:10.1016/S2665-9913(22)00192-8