Significance of global versus segmental subclassification of class III and IV lupus nephritis: a single center experience

Abstract

Introduction: Class III and IV are the most ominous among the classes of lupus nephritis (LN) and there are contradictory reports on whether LN class IV-G (global) differs from LN class IV-S (segmental), as envisaged by the International Society of Nephrolog and the Renal Pathology Society (ISN/RPS) 2003 classification. These subcategories are not validated for LN class III. This study was designed to assess the differences between global and segmental subclasses in classes III and IV of LN. Patients and Methods: In a retrospective analysis, the kidney biopsies of 84 patients with new-onset LN were analyzed. The Student's t-test and Mann-Whitney test were employed to compare differences between the means of continuous variables among the two groups. Fisher's exact test was used to compare the categorical variables. A p-value <0.05 was considered statitistically significant. Results: Of 84 patients, 69 (82.1) were females and 15 (17.9) males, with the female to male ratio of 4.6:1. The mean age of all patients was 32.7 +/- 12.6 years. The mean serum creatinine at the time of biopsy was 1.5 +/- 0.94 mg/dl (range: 0.7 to 5 mg/dl) and the mean urinary protein excretion was 1.6 +/- 1.9 g/day. Among 84 biopsies, 26(30.95) were classified as class III and 37 (44.05) to class IV LN. In class IV LN, serum creatinine was significantly higher in global versus segmental subcategory (2.4 +/- 1 vs. 1.1 +/- 0.5 mg/dl; p=0.034), while 24-h proteinuria was not significantly different between the subcategories (2.7 +/- 1.2 vs. 3.1 +/- 1.0 g/d, p=0.56). In LN class III, the mean age, serum creatinine and 24-hour proteinuria did not show significant differences between the global and segmental subcategories (37 +/- 17 vs. 30 +/- 15 years, p=0.58; 1.2 +/- 0.2 vs. 1.25 +/- 0.6 mg/dl, p=0.66; 2.03 +/- 0.5 vs. 3.1 +/- 3.5 g/day, p=0.45, respectively). The proportion of glomeruli showing endocapillary proliferation was significantly higher in global than in segmental subclasses (94.25 vs. 5.72; p=0.026) in class IV LN. The activity and chronicity percent also revealed higher values in global subclass vs. segmental subclass of class IV LN (p=0.038 and p=0.045, respectively). These parameters were not significantly different among the global and segmental subcategories of class III LN (p>0.5 for all parameters). Conclusion: In conclusion, our study showed significant differences in renal function and some pathological features on renal biopsies among the global and segmental subclasses of class IV LN. There were no significant differences among these subclasses of class III LN. Further, and larger studies are needed on this subject to substantiate the above results.