Worse renal outcome of subclass IV-G lupus nephritis patients over IV-S

Background International Society of Nephrology/ Renal Pathology Society (ISN/RPS) consensus on the classification of lupus nephritis (LN) subdivided class IV into diffuse segmental (IV-S) and diffuse global (IV-G). Nephrologists and nephropathologists believe that this subclassification would be clinically relevant based on hypothetical distinct immunopathogenesis of those subclasses guiding therapy as well as judging prognosis. Methods All adult patients with a renal biopsy-confirmed diagnosis of LN class IV undergoing regular follow-up in the Nephrology Division between January 2004 and December 2014 were enrolled excluding those with diabetes, hepatitis B, hepatitis C, HIV as well as those with insufficient clinical and hystopathological data. Biopsies were reviewed and reclassified according to ISN/RPS 2003 classification by two experienced pathologists and were examined by light microscopy and direct immunofluorescence. Results On baseline subclass IV-G compared to IV-S showed higher frequency of males and histologically higher activity (7.5 ± 2.8 vs 5.1 ± 2.3, p = 0.004) and chronicity index (3.4 ± 1.6 vs 2.4 ± 1.8, p = 0.016) as well as a higher percentage of epithelial crescents (12.9 vs 5.1, p = 0.0001) and vessel abnormalities (72% vs 42%, p = 0.017). Although renal function on baseline was not different between subclasses, IV-G showed lower levels, although not significant, of estimated glomerular filtration based on CKD-EPI formula (91.0 ± 34.8 vs 64.4 ± 44.5, p = 0.059) at the end of follow-up. In addition, we observed a higher rate of patients reaching CKD-EPI under 60 mL/min/1.73 m² in subclass IV-G over IV-S on last follow-up. Conclusion Subclasses IV-S and IV-G patients show some clinical and pathological differences that might represent distinct stages of the same disease and they should thus be treated the same.