Objectives: To study survival, renal outcome, and RNA polymerase III antibodies (RNAP Abs) as a risk factor for scleroderma renal crisis (SRC) in a Swedish cohort of systemic sclerosis (SSc) patients.
Methods: SRC was diagnosed in 16 SSc patients during the period from 1982 to 2010. For comparison, 112 (seven for each SRC patient) SSc patients without SRC were included. RNAP Abs were detected by a fully automated fluoroenzyme immunoassay (EliA). Values greater than 15 μg/L were considered positive. Frozen serum samples from the time of diagnosis of SSc were used.
Results: The 5- and 10-year survival rates were, respectively, 58% and 40% for SRC patients and 90% and 76% for patients without SRC (p < 0.001). The odds ratio (OR) for mortality was 4.39 [95% confidence interval (CI) 2.10-9.16, p < 0.001] in patients with SRC compared to those without SRC. Renal outcome was good in three patients. Haemodialysis was started in 10 patients and peritoneal dialysis in three. Renal function improved in three patients and dialysis was terminated. Four patients underwent renal transplantation. Seven SRC patients and nine without SRC were positive for RNAP Abs. Anti-RNAP Abs was a strong predictor of SRC. The sensitivity and specificity for development of SRC were 0.44 and 0.92, respectively. The OR for development of SRC was 8.90 (95% CI 2.68-29.6, p = 0.001) in RNAP-positive patients.
Conclusions: RNAP positivity is a strong risk factor for SRC. Renal outcome was variable and survival is still notably decreased.