Scleroderma in Cairns: an epidemiological study

Background Systemic sclerosis (SSc) refers to an autoimmune fibrosing disorder with high disease burden and mortality. The prevalence of 23/100 000 in South Australia (SA) is among the highest documented, but anecdotally it is higher still in Cairns. Aims To ascertain the prevalence of SSc in Cairns and surrounding regions, and to compare the demographic and clinical characteristics of patients with SSc in Cairns with those in SA. Methods Patients with SSc in Cairns were ascertained through hospital records and by referrals from specialist physicians in the region. These patients were interviewed and completed a structured questionnaire. Their physical findings and autoantibodies were recorded. These patients were compared with the SA patients enrolled in the Australian Scleroderma Cohort Study. Results A total of 81 patients was identified in Cairns, giving an estimated cross-sectional prevalence of 33.7/100 000. Among 65 patients interviewed in Cairns, 23 were born in Cairns, 16 had migrated to Cairns to ameliorate their Raynaud phenomenon and 26 for other reasons. The clinical features in both cohorts were similar, although Cairns had a lower prevalence of digital ulcers (30.8% vs 46.6%; odds ratio (OR) = 0.5035, 95% confidence interval (CI): 0.2839-0.8929, P = 0.0271) and higher prevalence of calcinosis (29.2% vs 17.0%; OR = 2.005, 95% CI: 1.055-3.382). Conclusions The higher prevalence of SSc in Cairns is partly, but not completely, due to migration. Differences in clinical features are not entirely explained by the warmer climate. There is a need for greater rheumatologic services in the Cairns region