Prognostic Factors of Renal Involvement in Systemic Sclerosis

Renal involvement is common in systemic sclerosis (SSc), including asymptomatic reduction of glomerular filtration rate (GFR), increased renal resistance indices, scleroderma renal crisis (SRC) and ANCA-associated vasculitis. The aim was to evaluate type and evolution of renal involvement for a period of five years.

121 SSc patients (100 F, 21 M) with mean age of 54.9 ± 13.8, disease duration of 9 ± 6 years, of which 62 had a diffused form and 59 limited form were enrolled. All patients were screened annually for renal function by laboratory examination, ultrasound and color Doppler ultrasound of renal arteries.

Over the five-year observation period, 6 SRC (3 M, 3 F) occurred, four of which required dialysis. One patient developed ANCA-related proliferative glomerulonephritis and the other one acute tubular necrosis. The remaining 113 patients had a preserved renal function (serum creatinine 0.75 ± 0.24 mg/dl, GFR 93.8 ± 20 ml/min, 24h proteinuria 0.20 ± 0.15 g). Doppler indices of intrarenal arterial stiffness increased with progression of capillaroscopic damage and with presence of digital ulcers. A negative correlation was observed between estimated GFR and pulsatile index (p< 0,05, r=-0.198), resistive index(p< 0,01, r=0.267), S/D ratio (p< 0,01, r=-0.237).

In SSc patients, renal function was normal for 4.1 years despite the presence of increased intrarenal arterial stiffness. SRC was observed in 4.9% of SSc patients. In SSc patients, a periodic follow-up based on clinical and laboratory evaluation, colorDoppler ultrasound and, in some cases, renal biopsy is required to evaluate renal involvement.