January 31, 2023
2 min read
This study was funding by the Swedish Research Foundation for Health, Working Life and Welfare; the Swedish Research Council; the AFA Foundation, Region Stockholm; King Gustaf V’s 80-year Foundation; and the Swedish Rheumatic Foundation. The authors report no relevant financial disclosures.
Inhalable substances associated with occupational settings may act as “important” environmental triggers for developing rheumatoid arthritis, according to data published in the Annals of the Rheumatic Diseases.
“Over recent years additional environmental inhalable exposures have been linked to risk for RA, including silica dust, asbestos and textile dust, whereas studies on effects of air pollution have yielded variable results,” Bowen Tang, MSc, of the department of medical epidemiology and biostatistics at the Karolinska Institute, in Stockholm, and colleagues wrote. “However, there is still a lack of knowledge of the impact on risk for RA from many different environmental exposures affecting airways that occur in occupational situations worldwide.”
To investigate the impact of occupational inhalants on the risk for developing RA, Tang and colleagues analyzed data from the Swedish Epidemiological Investigation of RA, which includes data from patients older than 18 years from south and central Sweden. Included cases were patients diagnosed with RA by a rheumatologist using the American College of Rheumatology 1987 or 2010 criteria. Control cases, meanwhile, were selected from a national register and matched based on age, sex and residential area.
Patients included in the analysis supplied job title information as well as their start and end dates for 14 working periods. The researchers employed a job-exposure matrix that was previously developed to measure working conditions in the country, which includes prevalence and concentration assessments for 47 inhalable agents. However, to achieve statistical power, Tang and colleagues retained only the agents with more than 50 exposed patients in their agent-specific analysis, resulting in a total of 32 agents.
The analysis included a total of 4,033 patients with RA and 6,485 matched controls. According to the researchers, exposure to any of the included inhalants was linked to an increased risk for RA (OR = 1.25; 95% CI, 1.12-1.38). This risk increased both with the number of exposed agents (P < .001) and with the length of exposure (P < .001). Patients who smoked, were exposed to inhalants and who had an increased genetic risk score demonstrated a “markedly elevated risk” for RA, compared with patients with none of those risk factors (OR = 18.22; 95% CI, 11.77-28.19), the researchers wrote.
Additionally, the researchers described “significant interactions” between occupational inhalable substances and smoking/genetic factors in patients with RA.
“Our study shows that inhalable, mainly occupational exposures act as important environmental risk factors in RA development, especially in ACPA-positive RA,” Tang and colleagues wrote. “The markedly increased risk for RA after exposure of smoking and occupational inhalable agents observed among individuals carrying genetic variants common in Swedish as well as in most Caucasian populations strongly suggests the implementation of broad preventive strategies such as quit smoking and mitigation of occupational hazards.”