Morphological Indexes: Can They Predict Lupus Nephritis Outcomes? A Retrospective Study.

Abstract

Lupus nephritis is a serious complication of systemic lupus erythematosus. Currently, therapy is guided by findings in the renal biopsy, following the International Society of Nephrology / Renal Pathology Society classification. Austin and Hill's histomorphological indexes are not routinely obtained. In this retrospective single-centre study, we aimed to analyze the importance and applicability of the different morphological indexes in predicting response to treatment and prognosis. Patients with kidney biopsy demonstrating lupus nephritis from the 2010 - 2016 period were included. We analyzed their demographic data, comorbidities, clinical presentation and laboratorial evaluation at the time of renal biopsy. We evaluated the following outcomes: clinical remission, renal function and proteinuria at end of follow-up. Histologic analysis was performed using the International Society of Nephrology / Renal Pathology Society classification and the morphological indexes described by Austin (Activity and Chronicity) and Hill. Univariate and multivariate statistical analysis was performed using STATA software. We analyzed 46 biopsy-proven lupus nephritis cases, with a median follow-up of 31.9 (13.2 - 45.6) months. Based on biopsy findings, 35 patients were started on immunosuppressive therapy. We observed that Class IV patients had, at presentation, lower estimated glomerular filtration rate (67.3 vs 94.6 mL/min; p = 0.02), higher proteinuria (4.26 vs 2.37 g/24 hours; p = 0.02) and a non-significantly higher C3 consumption (58.9 vs 77.4 mg/dL; p = 0.06). We did not observe correlations between International Society of Nephrology / Renal Pathology Society classification and the outcomes at the end of follow-up. In contrast, both the Hill biopsy index and Austin's Chronicity index were correlated with renal function and proteinuria at the end of follow-up. Austin's Activity index correlated with the immunological findings (C3, C4 and anti-dsDNA) at presentation. Because clinical activity poorly correlates with histologic activity, histological findings are fundamental when assessing patients with suspected lupus nephritis. The most recent International Society of Nephrology / Renal Pathology Society report supports the European League Against Rheumatism guidelines, encouraging the adoption of histomorphological indexes when evaluating lupus nephritis. Our data, showing a correlation between the renal outcomes and the indexes described by Austin and Hill, supports this view. The histomorphological indexes in lupus nephritis are easily obtainable, can predict renal outcomes and may help in the management of such patients.