Geographic variation as a risk factor for digital ulcers in systemic sclerosis patients: a multicentre registry

To evaluate the influence of geographic variation on the risk of digital ulcer (DU) development in systemic sclerosis (SSc) patients.

This cross-sectional, multicentre study evaluated patients with SSc from centres located in different geographic regions of Brazil (subtropical and tropical climate zones). Demographic and clinical data were collected.

The study included 141 patients with SSc (26 from the subtropical and 115 from the tropical zone). In total, 43 DUs were observed in 23 (16%) of the patients. By a simple logistic regression model, the presence of DUs was associated with a higher modified Rodnan skin score, previous necrosis or amputation of the extremities, flexion contracture of the fingers, active smoking, higher avascular score on capillaroscopy, higher severity of Raynaud's phenomenon, a higher Health Assessment Questionnaire Disability Index (HAQ-DI) score, a higher visual analogue scale score for Raynaud's phenomenon and overall disease, and the subtropical climate zone. Using multiple logistic regression, the presence of DUs was significantly associated with patients living in the subtropical climate zone [odds ratio (OR) = 5.4, p = 0.002], necrosis or amputation (OR = 5.2, p = 0.011), and a higher HAQ-DI score (OR = 2.6, p = 0.021).

In this multicentre study in a continental country with different climates, patients with SSc living in a subtropical climate region had a 5.4 times higher risk of developing DUs than patients living in a warmer region (tropical climate), suggesting a more severe course of peripheral vasculopathy among patients living in geographic regions with relatively cold weather.