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Commentary and Observations from
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Rheumatoid Arthritis and Air Pollution

Rheumatoid Arthritis and Air Pollution

The risk of developing rheumatoid arthritis (RA) has previously been linked to certain genetic and environmental factors. For example, smoking has been associated with—and remains one of the strongest risk factors for—the development of RA. More recent data has suggested that air pollution may be another environmental risk factor for developing RA. Several studies have linked poor air quality and air pollution to RA: In recently published studies, there is now data suggesting that air pollution may increase RA flares and disease activity and possibly diminish the response to certain RA treatment options, including biologic disease-modifying antirheumatic drugs (DMARDs).

Alsaber et al examined patients with RA from Kuwait who were registered in the Kuwait Registry for Rheumatic Diseases during the years 2013 through 2017. Disease activity was measured during hospital stays using Disease Activity Score-28 (DAS-28) and Clinical Disease Activity Index (CDAI) scores; air pollution data were obtained from the Kuwait Environmental Public Authority. Patients' data were linked with air pollution data according to date and patient address. The study detected an increased risk of RA in participants exposed to sulfur dioxide and nitrogen dioxide, but not to particulate matter (less than 10 μm in aerodynamic diameter), ozone, and carbon monoxide concentrations. Also based on DAS-28 and CDAI scores was a strong association between air pollution and RA disease activity.

Another study, out of Verona, Italy conducted by Adami et al found higher levels of disease flares among patients with RA exposed to higher levels of air pollution. The authors examined exposure to air pollutants 30 days and 60 days preceding a RA flare compared to 30 days and 60 days prior to a low-disease activity visit for patients with RA included in the study. Air pollution data was collected from multiple government testing sites around Verona that are monitored on a daily basis. Adami and colleagues also found higher C-reactive protein (CRP) levels in patients with RA who were exposed to higher amounts of air pollution. This elevated risk of disease flares and CRP levels was seen even at low levels of air pollutant exposures.

In a separate but similar study using data from Verona, Adami et al showed poorer response to biologic treatments in patients with RA, psoriatic arthritis, and ankylosing spondylitis followed over a 5-year period who were exposed to high levels of environmental air pollutants.

As seen in previous studies, there may be a correlation of air pollution with the risk of developing RA. There is now evidence of air pollution possibly leading to increased RA disease activity and even causing poorer response to biologic DMARDs used for the treatment of inflammatory arthritis. However, a causal relationship between environmental air pollution and these findings is still lacking.

  • Adami G, et al. Environmental air pollution is a predictor of poor response to biological drugs in chronic inflammatory arthritides. ACR Open Rheumatol. 2021;3:451.
  • Adami G, et al. Association between environmental air pollution and rheumatoid arthritis flares. Rheumatology (Oxford). 2021;60:4591.
  • Alsaber A, et al. Influence of ambient air pollution on rheumatoid arthritis disease activity score index. Int J Environ Res Public Health. 2020;17:416.
  • Hart JE, et al. Exposure to traffic pollution and increased risk of rheumatoid arthritis. Environ Health Perspect. 2009;117:1065.
  • Shin J, et al. Association between exposure to ambient air pollution and rheumatoid arthritis in adults. Int J Environ Res Public Health. 2019;16:1227.

Filed under: Public Health, Rheumatology

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