There are more people with scleroderma in Cairns than any other region of Australia, but migration only partly explains the phenomenon, researchers report.

Cairns based rheumatologist Zia-Ur Rehman and colleagues noted that the prevalence of scleroderma (SSc) in Australia, particularly South Australia, is reported to be among the highest in the world at 23 per 100,000.

Yet anecdotal evidence suggested that the prevalence was even higher in Cairns and Far North Queensland.

The study published in Internal Medicine Journal  identified 81 patients from medical records at the Cairns Hospital who fulfilled the 2013 ACR/EULAR diagnostic criteria for SSc. 65 of the patients were subsequently interviewed and the data was compared with the SA patients enrolled in the Australian Scleroderma Cohort Study.

A prevalence of SSc of 33.7 per 100,000 was calculated for Cairns, which the authors noted was  significantly greater than the prevalence in SA.

When the authors excluded the 16 patients who had migrated to Cairns to alleviate their symptoms the prevalence estimate was still equivalent to the highest rates in the world, at 27.1 per 100,000.

There was considerable variability in the estimated prevalence of SSc in different areas of the Cairns region, ranging from 16.5 per 100,000 in the ‘Port Douglas – Daintree’ area to 51.8 per 100,000 in the ‘Gordonvale – Babinda’ area.

The pattern of disease seen in the two cohorts was very similar, but the prevalence of complications such as reflux oesophagitis and calcinosis and the patients’ perceived impact of SSc was greater in the Cairns cohort.

The study authors noted that only one rheumatologist served the Cairns region (equivalent to 0.42 rheumatologists per 100,000 population), in contrast to the 2 rheumatologists per 100,000 recommended in international models.

“The prevalence of SSc in the Cairns region is high compared to elsewhere, and is greater than that of SA. This can, in part, be attributed to the migration of patients with SSc towards the tropics but further studies are required to investigate why SSc is more prevalent in the Cairns region,” they concluded.