Is exposure to environmental factors associated with a characteristic clinical and laboratory profile in systemic sclerosis? A retrospective analysis

Abstract

To identify environmental factors (EF) in a large cohort of patients with systemic sclerosis (SSc) analyzing their clinical and laboratory presentation. A cohort of consecutive patients attended at a single Brazilian SSc outpatient clinic was analyzed regarding EF. Data were analyzed according to clinical, demographic and laboratory characteristics, as well as SSc subtype. In a cohort of 662 patients, 70 (10.6%) had known previous exposure to EF, predominantly organic solvents (51.4%), silica (20%), silicone (12.9%) and pesticides (11.4%). In the SSc cohort, patients with EF had a significantly higher frequency of male gender (p < 0.01), African-Brazilian ethnicity (p = 0.01), myopathy (p = 0.02), and pigmentary disorders (p = 0.04), with shorter disease duration (p = 0.01). When SSc subtypes were analyzed separately, there was positive association with male gender in limited (p < 0.01) and diffuse (p < 0.01) SSc, as well as African-Brazilian ethnicity (p = 0.04), severe interstitial lung disease (p < 0.01), myopathy (p = 0.02) and SD pattern at nailfold capillaroscopy (p = 0.01) in limited SSc, and negative association with esophageal hypomotility (p < 0.01) and ANA positivity (p = 0.02) in diffuse SSc. Multiple regression analyses showed that myopathy was independently associated with previous exposure to EF (OR = 2.09; 95% CI 1.15-3.82), especially silica exposure (OR = 3.09; 95% CI 1.67-5.73). This study showed that SSc patients with previous exposure to EF may have some specific clinical characteristics, mainly a higher frequency of myopathy, also showing more severe ILD, preferably in male and African-Brazilian patients, associated with a lower frequency of ANA positivity.

Keywords: Ethnicity; Gender; Myopathy; Occupational factors; Organic solvents; Silica; Systemic sclerosis.