Clinical and histopathological predictors of systemic lupus erythematosus in a South American cohort of patients with full-house glomerulonephritis.

Abstract

ObjectivesOur aim was to evaluate clinical and renal histopathological variables associated with the diagnosis of Systemic Lupus Erythematosus (SLE) in a South American cohort with Full-House (FH) glomerulonephritis (GN) in order to distinguish it from other causes of FHGN.MethodsObservational retrospective study. Kidney biopsies performed in our hospital between 2000 and 2019 were reviewed, identifying those with a FH pattern. Clinical, analytical, and histopathological data were collected. Patients were classified as SLE with Lupus - FHGN (if they met ACR 1997 and/or SLICC 2012 and/or ACR-EULAR 2019 SLE criteria) and as non-Lupus FH GN (idiopathic or secondary). Descriptive statistics, univariate and multivariate logistic regression analysis were performed to identify factors associated with Lupus- FHGN, and Kaplan-Meier survival curves were used to compare renal survival between both groups.Results181 patients with FHGN were included, 124 women (68.5%), with a mean age of 41.1 years (SD 16.0) and a median post-biopsy follow-up time of 2.9 years (IQR 0.4-6.8 years). 116 patients (64.1%) met SLE criteria (103 with extrarenal manifestations and 13 with renal-limited lupus), 52 patients presented identifiable secondary causes of FHGN and 13 remained idiopathic FHGN. Renal biopsies in Lupus - FHGN presented more frequently 3 or 4 crosses of IgG, C3 and C1q deposits (p < 0.001) and had less moderate/severe involvement of the tubulointerstitial compartment (p < 0.001), when compared with non-Lupus FHGN. In the multivariate analysis, the factors that remained associated with Lupus - FHGN were: female sex, younger age, positive ANA, anti-DNA, and 3 or 4 crosses of C1q deposits. Lupus - FHGN showed a protective effect for the development of End-Stage Renal Disease (ESRD) in the univariate analysis (HR 0.34, 95% CI 0.13-0.89) but this association was not significant in the multivariate analysis.ConclusionsIn this South American cohort, 35.9% of FHGN were not associated with SLE diagnosis. Female sex, younger age, positive ANA or anti-DNA antibodies and marked C1q deposits at renal biopsy were associated with SLE diagnosis.