Longitudinal study of renal function in systemic sclerosis.

OBJECTIVE: To determine the prevalence of renal disease and the course of renal function over time in patients with systemic sclerosis (SSc). METHODS: We performed a multicenter, longitudinal study of 561 patients with SSc followed in the Canadian Scleroderma Research Group registry. Renal function was measured by the estimated creatinine clearance rate (eCcr) using the Cockcroft-Gault formula. Longitudinal changes in renal function were modeled using statistical analyses that adjusted for patient dropout. RESULTS: Among the study subjects, 112 (20%) had abnormal renal function with no history of scleroderma renal crisis (SRC) and 29 (5%) had a history of SRC at baseline. In models adjusting for patient dropout, we found that patients with abnormal baseline renal function experienced the same annual decline in eCcr as patients with normal baseline renal function (-0.89% per year, 95% CI -2.02%, 0.26%), which is similar to that observed in the general population. Patients with a history of SRC also showed the same rate of decline, although starting from a lower baseline. CONCLUSION: Renal dysfunction is common in SSc, even among those without a history of SRC. It is generally mild and renal function declines at a rate similar to the general population. These data are of considerable prognostic value for clinicians caring for patients with SSc.