Occupation as a gendered-role and outcome in systemic sclerosis

Sex and gender are of growing scientific interest in disease onset and course. While sex differences have been shown to exist in systemic sclerosis, there is a paucity of data on gender. Our objective was to examine the association between occupation, a gender-related role and outcomes in systemic sclerosis. An occupation score ranging from 0 to 100, with lower scores representing occupations traditionally held by men and higher scores traditionally held by women, was constructed using the National Occupational Classification 2016 and data from Statistics Canada. Subjects in the Canadian Scleroderma Research Group registry were assigned an occupation score based on self-reported occupation. Multivariate models, adjusted for sex, age, smoking and education were used to estimate the independent effect of occupation score on systemic sclerosis outcomes. We included 1104 subjects, of which 961 were females (87%) and 143 (13%) males. There were differences between females versus males: disease duration (9.9 vs 7.6 years, p = 0.002), diffuse disease (35% vs 54%, p < 0.001), interstitial lung disease (28% vs 37%, p = 0.021) and pulmonary hypertension (10% vs 4%, p = 0.033), but not pain, response to treatment and mortality. The median occupation scores differed between females and males (84.3 (interquartile range 56.8, 89.4) vs 24.9 (4.3, 54.1), p < 0.001). The Spearman correlation between sex and occupation score was 0.44, indicating a weak correlation. In adjusted analyses, occupation score was not an independent predictor of disease subset (diffuse vs limited), interstitial lung disease, pulmonary hypertension, pain, response to treatment or mortality. We did not find independent associations between an occupation score, a gender-related role and outcomes in systemic sclerosis. These results should be interpreted with caution as occupation may be a poor measure of gender. Future research using a validated measure of gender will be needed to generate robust data on the effect of gender in systemic sclerosis.