Utility of remission criteria for the renal prognosis of IgA nephropathy

Factors related to recurrence of proteinuria in childhood IgA nephropathy

BACKGROUND

Proteinuria remission is the most significant predictive factor for kidney outcome in childhood IgA nephropathy (c-IgAN). Even if proteinuria remission can be obtained, some patients have recurrence of proteinuria in the long-term.

METHODS

This is a retrospective analysis of 312 cases of proteinuria remission among 538 consecutive children with biopsy-proven IgAN from 1976 to 2013. To elucidate the incidence and factors related to recurrence of proteinuria in c-IgAN, we compare clinical and pathological findings between patients with and without recurrence of proteinuria.

RESULTS

Among 312 patients with remission of proteinuria, 91 (29.2%) had recurrence of proteinuria within the observation period (median 8 years). Using a multivariate Cox regression analysis, significant factors associated with recurrence of proteinuria were onset age (HR 1.13 [95%CI: 1.05-1.22], P = 0.002) and presence of hematuria after proteinuria remission (HR 2.11 [95%CI: 1.30-3.45], P = 0.003). The Kaplan-Meier analysis showed significant differences in CKD G3a-G5-free survival between the patients with no-recurrence of proteinuria, recurrence of proteinuria and non-proteinuria remission (P < 0.0001, log-rank test). Kidney survival was 100% in no-recurrence of proteinuria, 92.2% in recurrence of proteinuria, and 65.6% in non-proteinuria remission at 15 years. Cox analyses adjusted by proteinuria remission showed that recurrence of proteinuria (HR 03.10e9 [95%CI: NA], P = 0.003) was a significant factor associated with progression to CKD G3a-G5 in all patients with c-IgAN.

CONCLUSIONS

Approximately 30% of patients with proteinuria remission had recurrence of proteinuria regardless of treatment. Both remission and recurrence of proteinuria are significant prognostic factors for kidney outcome. A higher resolution version of the Graphical abstract is available as Supplementary information.

Current treatment status of IgA nephropathy in Japan: a questionnaire survey

BACKGROUND

In 2020, the Committee of Clinical Practical Guideline for IgA Nephropathy (IgAN) revised the clinical practice guidelines. Herein, we conducted a questionnaire survey to assess the potential discrepancies between clinical practice guidelines and real-world practice in Japan.

METHODS

A web-based survey of members of the Japanese Society of Nephrology was conducted between November 15 and December 28, 2021.

RESULTS

A total of 217 members (internal physicians: 203, pediatricians: 14) responded to the questionnaire. Of these respondents, 94.0% answered that the clinical practice guidelines were referred to "always" or "often." Approximately 66.4% respondents answered that histological grade (H-Grade) derived from the "Clinical Guidelines for IgA nephropathy in Japan, 3rd version" and the "Oxford classification" were used for pathological classification. Moreover, 73.7% respondents answered that the risk grade (R-grade) derived from the "Clinical Guidelines for IgA nephropathy in Japan, 3rd version" was referred to for risk stratification. The prescription rate of renin-angiotensin system blockers increased based on urinary protein levels (> 1.0 g/day: 88.6%, 0.5-1.0 g/day: 71.0%, < 0.5 g/day: 25.0%). Similarly, the prescription rate of corticosteroids increased according to proteinuria levels (> 1.0 g/day: 77.8%, 0.5-1.0 g/day: 52.8%, < 0.5 g/day: 11.9%). The respondents emphasized on hematuria when using corticosteroids. In cases of hematuria, the indication rate for corticosteroids was higher than in those without hematuria, even if the urinary protein level was 1 g/gCr or less. Few severe infectious diseases or serious deterioration in glycemic control were reported during corticosteroid use.

CONCLUSION

Our questionnaire survey revealed real-world aspects of IgAN treatment in Japan.

Microscopic hematuria as a risk factor for IgAN progression: considering this biomarker in selecting and monitoring patients

Hematuria-either macroscopic hematuria or asymptomatic microscopic hematuria-is a clinical feature typical but not specific for immunoglobulin A nephropathy (IgAN). The only biomarker supported by the Kidney Disease: Improving Global Outcomes group as a predictor of progression, identifying patients needing treatment, is proteinuria >1 g/day persistent despite maximized supportive care. However, proteinuria can occur in the setting of active glomerulonephritis or secondary to sclerotic renal lesions. Microscopic hematuria is observed in experimental models of IgAN after IgA-IgG immunocomplex deposition, activation of inflammation and complement pathways. Oxidative damage, triggered by hemoglobin release, is thought to contribute to the development of proteinuria and progression. Despite being a clinical hallmark of IgAN and having a rational relationship with its pathophysiology, the value of microscopic hematuria in assessing activity and predicting outcomes in patients with IgAN is still debated. This was partly due to a lack of standardization and day-to-day variability of microhematuria, which discouraged the inclusion of microhematuria in large multicenter studies. More recently, several studies from Asia, Europe and the USA have highlighted the importance of microhematuria assessment over longitudinal follow-up, using a systematic approach with either experienced personnel or automated techniques. We report lights and shadows of microhematuria evaluation in IgAN, looking for evidence for a more consistent consensus on its value as a marker of clinical and histological activity, risk assessment and prediction of treatment response. We propose that hematuria should be included as part of the clinical decision-making process when considering when to use immunosuppressive therapy and as part of criteria for enrollment into clinical trials to test drugs targeting the inflammatory reaction elicited by immune pathway activation in IgAN.