Prevalence of systemic sclerosis in south-east Norway

To assess the prevalence of SSc in south-east Norway.

The survey was conducted in south-east Norway with a denominator population of 2,707,012, 56% of the total Norwegian population. All SSc patients living in the study area between 1 January 1999 and 31 December 2009 were included. Patients were identified by five overlapping acquisition routes, including all the rheumatology departments, private rheumatologists and the dermatology department in the study area. Only cases meeting the 1980 ACR and/or the Medsger and LeRoy classification criteria were included. The patients were assigned to three clinical subsets: limited SSc, lcSSc or dcSSc.

At the end of the study period, a total of 269 patients fulfilled the ACR and/or the Medsger and LeRoy SSc criteria, giving a point prevalence of 9.9/100,000 (95% CI 8.8, 11.2). The estimated prevalences of lSSc, lcSSc and dcSSc were 1.3/100,000, 6.9/100,000 and 1.8/100,000 (95% CIs 0.9, 1.8; 5.8, 7.8; 1.4, 2.5), respectively. The mean age at onset was 47 years and the female:male ratio was 3.8:1. The prevalence estimates of SSc in the 10 different counties in south-east Norway varied between 5.2 and 14.4/100,000 (95% CIs 2.8, 8.8; 10.3, 19.6).

This study establishes baseline estimates of the occurrence and disease characteristics in a large, unselected group of Norwegian SSc patients. Our data suggest that the prevalence of SSc in Norway is comparable with other northern European countries, supporting the notion of a north-south gradient of SSc in Europe with the lowest prevalence in northern Europe.