Predictive value of sub classification of focal segmental glomerular sclerosis in Oxford classification of IgA nephropathy

Background The Oxford classification of IgA nephropathy (IgAN) was revised in 2016 which lacked sufficient evidence for prognostic value of subclassification of focal segmental glomerular sclerosis (S lesion), and the proper proportion of S lesion for subclassification remains undetermined. Aim This study aimed to explore the predictive value of the new subclassification of S score on renal outcomes of IgAN patients. Methods 348 patients with IgAN-associated S lesion were enrolled. According to the optimal cut-off of 25% established by receiver operating characteristic (ROC) curves, we divided S1 patients into two groups: S1a group (S lesion < 25%) and S1b group (S lesion >= 25%). IgAN patients with mild lesion (M0E0S0T0C0) were set as the control group. The clinical features at renal biopsy, pathological findings, and follow-up parameters (follow-up time ranged from 1 to 5 years) were collected. We used univariate and multivariate analyses to assess whether the subclassification of S score could refine risk prediction and clinical utility. Results We demonstrated that S lesion >= 25% was associated with a more rapid GFR loss and a lower rate of complete remission of proteinuria even adjusted for multiple clinic pathological variables, compared to S1a group (All p values <.05). And the ratio of glomeruli with T lesion and crescents were higher in patients with S lesion >= 25%. Data showed that IgAN patients with S lesion >= 25% were at an increased risk of poor renal outcomes even with immunosuppression. Conclusion This study might recommend new subclassification of S scores (S0 (no S lesion), S1 (S lesion <25% of glomeruli), and S2 (S lesion >= 25% of glomeruli)) for the Oxford classification. This model may also help to evaluate pros and cons of immunosuppressive therapy in IgAN patients with different level of S lesion. KEY MESSAGES S lesion >= 25% is an independent risk factor for poor renal outcome in IgAN patients. This new subclassification of S scores may help to evaluate pros and cons of immunotherapy in IgAN patients with different level of S lesion.

Automated summary

This study found that S lesion >= 25% is associated with a more rapid decline in glomerular filtration rate and a lower rate of complete remission of proteinuria, even when adjusted for multiple clinicopathological variables, compared to the S1a group (all p values <0.05). Patients with S lesion >= 25% also had a higher proportion of glomeruli with T lesion and crescents. This suggests that IgAN patients with S lesion >= 25% are at increased risk of poor renal outcomes, even with immunosuppressive therapy.