Reduced incidence of Crohn's disease in systemic sclerosis: a nationwide population study.

Background: To date, there has been no studies to evaluate the incidence of Crohn's disease in systemic sclerosis patients. The goals of this study were to evaluate the incidence of Crohn's disease and its relationship with sex and age in patients with systemic sclerosis.
Methods: We enrolled patients with systemic sclerosis and controls from Taiwan's Registry of Catastrophic Illness Database and National Health Insurance Research Database. Every systemic sclerosis patient was matched to at most three controls by sex, age, month and year of initial diagnosis of systemic sclerosis. The standardized incidence ratio (SIR) of Crohn's disease in systemic sclerosis patients, and 95% confidence interval (95% CI) were calculated. Cox hazard regression was used to calculate the hazard ratio (HR).
Results: The study enrolled 2,829 patients with systemic sclerosis and 8,257 controls. Male and female patients with systemic sclerosis both had lower rates of incident Crohn's disease (SIR: 0.18, 95% CI = 0.05-0.62; SIR: 0.10, 95% CI = 0.05-0.21, respectively). The risk of incident Crohn's disease in systemic sclerosis was still lower than in controls when we stratified the patients according to their ages. In Cox hazard regression, the hazard rates of Crohn's disease were lower in systemic sclerosis patients after adjusting for genders and ages (HR: 0.12, 95% CI = 0.06-0.21, p < 0.001).
Conclusions: Systemic sclerosis is associated with decreased incidence of, irrespective of sex and age of the patients.