Occupational exposure to toxicants may predict lung function decline in systemic sclerosis

Among patients with systemic sclerosis, occupational exposure to toxicants independently predicted decline in lung function, regardless of sex, researchers reported in Chest.

The multicenter, retrospective study included 210 patients with systemic sclerosis (median age, 65 years; 35.4% men) from 1999 to 2018 who underwent standardized quantitative assessment of occupational exposure via a cumulative exposure score. Researchers evaluated the association between occupational exposure via the cumulative exposure score and patient characteristics.

More than one-third of patients (37.6%) had occupational exposure to toxicants. The most frequent exposures were to chlorinated solvents (25.2%), crystalline silica (14.3%) and epoxy resins (11%).

The researchers reported a strong association between male sex and occupational exposure to toxicants (OR = 10.3; 95% CI, 5.1-21.9; P < .0001). The median number of exposed toxicants was three in men and one in women (P = .008). Compared with women, men had higher cumulative exposure scores (22.5 vs. 2.9; P < .0001) and cumulative exposure duration (23 years vs. 11 years; P < .0001).

In a multivariable analysis, the cumulative exposure score was inversely correlated and independently associated with FVC decline over time and with FVC decline of 10% or more from baseline (P < .05 for both), but not male sex. Cumulative exposure score was not associated with a decline in the hemoglobin-corrected transfer coefficient for carbon monoxide in the lung of 15% or more, the researchers wrote.

Researchers observed no independent association between sex and decline in FVC or the hemoglobin-corrected transfer coefficient for carbon monoxide in the lung. Male sex and cumulative exposure score were not associated with shorter time to decline in FVC of 10% or more or a decline in the hemoglobin-corrected transfer coefficient for carbon monoxide in the lung of 15% or more.

“In view of the dose-dependent association between occupational exposure and decline in FVC over time, these results raise the hypothesis of a potential benefit to early treatment in systemic sclerosis patients with occupational exposure,” Benjamin Thoreau, MD, MSc, PhD student in the department of immunology at Cochin Institute, Paris, and the department of internal medicine and clinical immunology at the Regional Competence Center for Systemic and Autoimmune Rare Diseases at Bretonneau Hospital, Tours, France, and colleagues wrote.