Is air pollution affecting the disease activity in patients with systemic lupus erythematosus? State of the art and a systematic literature review

Objective: It has been documented that several major components of air pollution, including trace elements and polycyclic aromatic hydrocarbons, are associated with the prevalence of systemic lupus erythematosus (SLE). However, the impact of air pollution on the SLE disease activity is still elusive. In this paper, we review the current evidence investigating the link between air pollution, especially when measured as PM2.5, and SLE severity and activity. Methods: A detailed literature search was applied a priori to the Ovid MEDLINE In-Process and Other Non-Indexed Citation 1986 to present. Presented abstracts from the European League Against Rheumatism and American College of Rheumatology (ACR)/Association for Rheumatology Health Professionals (ARHP) Annual Meetings (2011-2018) were also screened. Results: Out of a total of 1354 papers retrieved from search and references list for detailed evaluation, data from 652 patients with SLE from three studies were analyzed. Two studies had an observational longitudinal design, counting for 348 patients with a follow-up of 24 months and 79 months. Retrieved studies differed for disease activity assessment and air pollution quantifications. Conclusion: Current evidence suggests that variations in air pollution may influence the disease activity in patients with SLE. However, the sample size, methodological biases, and differences across the studies make further research mandatory. Understanding the increased burden of SLE and its complications, not only from a medical, but also from a socio-demographic perspective, including an exposure to pollutants, should have implications for resource allocation and access to subspecialty care.