Renal arterial resistive index as a prognostic marker in lupus nephritis patients

Introduction: Lupus nephritis (LN) is known to be one of the most serious complications of SLE and it is a major predictor of poor prognosis. Despite the improvement in understanding the pathophysiology of lupus nephritis and greater improvement in diagnostic approaches, lupus nephritis patients have poorer outcomes Objectives: Study the relation between renal resistive index (RRI) and renal function and histopathological parameters in lupus nephritis (LN) patients. Also to investigate the usefulness of RRI in predicting response to treatment. Patients and methods: This study included 126 patients who were split into 2 groups (group 1; 101 LN patients and group 2; 25 SLE patients without renal affection); and100 healthy controls (group 3). The RRI was measured for all participants through a colored Doppler ultrasound examination. LN patients underwent renal biopsy and received their therapy and were followed up for 6 months. Results: The RRI was significantly greater in the LN group (mean ± SD; 0.64±0.07) than in SLE patients without nephritis (0.5884±0.04) ( P<0.0001). The RRI was greater in LN class Ⅳ ( P< 0.0001). RRI significantly correlated with the chronicity index (r =0.704, P<0.0001), activity index (r =0.310, P=0.002), and serum creatinine (r =0.607, P<0.0001) and negatively correlated with eGFR (r = -0.719, P <0.0001). Almost Eighty-five percent (84.8%) of LN patients responded to induction therapy. RRI was significantly greater in the nonresponder group (mean±SD, 0.73±0.02) than that in the responder group (0.63±.07) ( P< 0.0001). All non-responders to induction therapy while only 29.8% of responders had an RRI of ˃ 0.7. RRI, according to regression analysis was a significant predictor of response to treatment in LN patients Conclusion: RRI was significantly greater in the LN group and significantly correlated with kidney function and histopathological parameters. RRI can predict response to induction therapy in LN patients.