Calcinosis is associated with digital ischaemia in systemic sclerosis-a longitudinal study.

OBJECTIVE

To determine if ischaemia is a causal factor in the development of calcinosis in SSc.

METHODS

Patients with SSc were assessed yearly. Physicians reported the presence of calcinosis, digital ischaemia (digital ulcers, digital necrosis/gangrene, loss of digital pulp on any digits and/or auto- or surgical digital amputation) and nailfold capillary dropout assessed using a dermatoscope. The number of digits with digital ischaemia was used as an assessment of the severity of digital ischaemia. SSc specific antibodies were detected with a line immunoassay. Multiple logistic regression and Cox proportional hazards models were generated to determine associations between calcinosis, digital ischaemia and capillary dropout.

RESULTS

One thousand three hundred and five patients were included in this study, of whom 300 (23.0%) had calcinosis at study entry. In a cross-sectional multivariate analysis, at baseline, calcinosis was associated with digital ischaemia (odds ratio (OR) = 2.37, 95% CI: 1.66, 3.39), severity of ischaemia (OR = 1.12, 95% CI: 1.06, 1.18), capillary dropout (OR = 1.41, 95% CI: 1.05, 1.89), ACAs (OR = 1.68, 95% CI: 1.17, 2.43) and anti-RNA polymerase III antibodies (OR = 1.77, 95% CI: 1.08, 2.89). Current use of calcium channel blockers was inversely associated with the presence of calcinosis (OR = 0.70, 95% CI: 0.52, 0.96). Of the 805 patients with no calcinosis at study entry and at least one follow-up visit, 215 (26.7%) developed calcinosis during follow-up. Significant baseline predictors of the development of calcinosis in follow-up were digital ischaemia (hazard ratio (HR) = 1.82, 95% CI: 1.30, 2.54), capillary dropout (HR = 1.46, 95% CI: 1.08, 1.99), dcSSc (HR = 1.57, 95% CI: 1.11, 2.21), ACA (HR = 2.18, 95% CI: 1.50, 3.17) and anti-RNA polymerase III antibodies (HR = 2.58, 95% CI: 1.65, 4.04).

CONCLUSION

Ischaemia may play a role in the development of calcinosis in SSc.