Characteristics and Outcomes of Male Participants in a Multicenter Longitudinal Australian Study Cohort

OBJECTIVE: The aim of this study was to determine the differences in demographic, serologic, and clinical characteristics between male and female patients with systemic sclerosis (SSc) in an Australian cohort. METHODS: This was a retrospective observational study using data from the Australian Scleroderma Cohort Study. Male patients were compared to female patients using chi-square test, Wilcoxon rank-sum test, and Student's t-test. Survival analysis from time of diagnosis to all-cause mortality was presented on Kaplan-Meier curves, and a multivariate Cox proportional hazards model was used to evaluate independent predictors of all-cause mortality. A subanalysis of patients with incident SSc, defined as disease duration less than four years from onset of first non-Raynaud phenomenon manifestation to recruitment, was performed. RESULTS: Of the 2,033 participants, 299 were male, with a female-to-male ratio of 5.8:1. Male patients were more likely to present with diffuse skin involvement (43.7% vs 23.6%, P < 0.001) and ever be positive for digital ulcers, digital pitting, gangrene, and tendon friction rubs as well as myositis and interstitial lung disease. Male patients were more likely to have anti-Scl-70, anti-Jo-1, anti-PM/Scl and anti-RNA polymerase III antibodies compared to female patients. Male patients reported more exposure to silica dust, organic solvents, vinyl chloride, and epoxy resin compared with female patients. In the incident cohort, male patients had statistically significantly higher mortality, with 60% of male patients compared to 82% of female patients surviving 10 years from diagnosis (P < 0.001). CONCLUSION: Male patients with SSc have more extractable nuclear antigen antibody positivity and reduced survival in comparison to female patients. The significant difference between occupational exposures recorded between sexes warrants further investigation into the role of industrial exposures in the pathogenesis of SSc in male patients.