Ultrasonographic Evaluation of Renal Resistive Index in Patients with Lupus Nephritis: Correlation with Histologic Findings

We analyzed the association between the renal arterial resistive index (RI) and the histologic features of lupus nephritis. All consecutive patients with systemic lupus erythematosus (SLE) who required a kidney biopsy were enrolled. The study protocol included ultrasonographic assessment to measure the RI and kidney biopsy (International Society of Nephrology/Renal Pathology Society classification). A RI > 0.7 was considered pathologic. Patients with non-renal SLE and healthy patients were studied as control groups. We enrolled 42 patients with renal SLE, 10 with non-renal SLE and 14 healthy patients: their mean (±standard deviation) RI values were 0.64 ± 0.08, 0.60 ± 0.04 and 0.59 ± 0.01, respectively (p = not significant). RIs > 0.7 were recorded only in patients with renal SLE (5/42, 11.9%). The percentage of patients with a pathologic RI was significantly higher in class IV nephritis in comparison with other classes (p < 0.009). In conclusion, we found a significant correlation between pathologic RI and class IV nephritis, suggesting a role for RI as a severity marker.