Scleroderma renal crisis: observations from the South Australian Scleroderma Register.

Background: Scleroderma renal crisis (SRC) is a rare but feared complication with high morbidity and mortality. Its aetiopathogenesis is unclear.

Aim: To investigate epidemiological, serologic and clinical features of all patients with SRC listed on the population-based South Australian Scleroderma Register and to examine possible factors in aetiopathogenesis.

Method: A case note review was performed on all SRC patients with relevant data extracted to determine incidence, clinical phenotype, presence of autoantibodies and survival. Possible precipitating and aetiopathogenic factors were also examined. Data from the South Australian Scleroderma Register and Australia Bureau of Statistics was sourced for comparative purposes.

Results: Over the 34-year period (1985-2018), 30 patients (21 females, 9 males) presented with SRC giving a South Australian mean annual incidence of 0.58/million/year (95% CI 0.39-0.89). Twenty-eight of these patients had diffuse cutaneous scleroderma and two with limited cutaneous scleroderma. The mean age at first symptom of scleroderma was 51.2 ± 15.9 (mean ± SD) years with SRC occurring 4.6 years later (median = 3.0 years, range 0.1-20 years). Possible precipitating factors for SRC included high dose steroids in five patients. Twelve patients were anti- RNA polymerase3 (RNAPol3) positive and two were anti-topoisomerase 1 (Topo1) positive. Renal outcome was poor with 13 patients requiring renal replacement therapy and two proceeding to renal transplantation. The mean age at death was 61.2 ± 11.6 years with SRC patient survival being significantly shorter than patients with diffuse scleroderma without renal involvement (P = 0.002). There was no significant difference in survival between the 1985-2002 and the 2003-2018 SRC cohorts (P = 0.2). Nailfold capillaroscopy performed in 10 patients revealed extensive microvascular damage with prominent capillary drop out.

Conclusion: SRC is a rare occurrence with an incidence of 0.58/million/year in South Australia. This frequency has not changed over time. It continues to have a severe adverse outcome with frequent requirement for renal replacement therapy and poor survival. Nailfold capillaroscopy revealed evidence of extensive capillary damage. No improvement in survival was observed over the 34-year study period.