HOW REGIONAL PERSPECTIVES SHAPE GLOBAL TRENDS IN IGA NEPHROPATHY: A COMPREHENSIVE CHART REVIEW ACROSS US, EU5, JAPAN, AND CHINA

IgA nephropathy (IgAN) is a leading cause of chronic kidney disease and progression to kidney failure worldwide. Management strategies vary across geographies, influenced by drug availability, healthcare systems, and physician mindset. While prior cross-regional studies have described treatment patterns, they were conducted before the approval and adoption of targeted therapies such as sparsentan, Iptacopan, telitacicept, and targeted-release budesonide.

As we approach another round of innovations in targeted IgAN therapies[TH1]  (e.g., APRIL/BAFF, anti-CD38), we chose to address this gap. We conducted an integrated comparative analysis of harmonized patient record audits across the US, EU5, Japan, and China in the post-approval targeted therapy era.

·       Data were drawn from Spherix Global Insights’ Patient Chart Dynamix™: IgAN series (2023–2025).

·       Nephrologists across the US, EU5, Japan, and China provided patient chart data for their most recent non-dialysis IgAN cases (≥15 mL/min/1.73m² eGFR).

·       Standardized questionnaires captured demographics, disease status, treatment history, proteinuria targets, and future therapy expectations.

Innovation Mindset: US and EU5
In the US and EU5, targeted therapies such as budesonide, sparsentan, and iptacopan are being adopted, yet about one-quarter (US) to one-third (EU5) of patients still advance despite therapy. While KDIGO awareness is consistent across regions, EU5 physicians report that country-level access and reimbursement differences influence adoption speed, highlighting a readiness to innovate but an uneven ability to implement

High-intensity Treatment Mindset: Japan
In Japan, nephrologists set the most aggressive proteinuria targets (≤0.5 g/day, often ≤0.3 g/day) and nearly half of patients undergo tonsillectomy, with 71% of physicians considering it effective. This reflects a uniquely rigorous therapeutic strategy, distinct from the innovation-driven US/EU5 approach. This preference also reflects both distinct disease pathology observed in Japanese IgAN cohorts and the limited availability of newly approved targeted therapies, leaving tonsillectomy and steroid pulses as the primary evidence-supported interventions.

Conservative/system-constrained mindset: China
In China, ~44% of patients present at CKD stage 3 or later (cohort mean eGFR ≈61; proteinuria ≈2.3 g/day).Physicians face the dual challenge of later referral and higher baseline burden, and practice patterns remain anchored by steroids despite high awareness of telitacicept nearly 18 months post approval, due in part to system constraints (not yet reimbursed nationally, and use confined to major hospitals).

Differences in referral patterns — later in China, earlier in Japan, and intermediate in the US/EU5 — interact with physician philosophies to shape IgAN care trajectories across regions. Despite these differences in practice, uncontrolled proteinuria and disease progression remain common. Regional patterns reflect both drug availability and physician philosophy.

Conclusion

Despite differences in drug availability, referral timing, and treatment strategies, a consistent reality emerges: many IgAN patients remain uncontrolled worldwide. These contrasts reflect not only systemic barriers but also deeply rooted physician philosophies — innovation readiness in the US/EU5, rigorous intensity in Japan, and therapeutic conservatism in China. As access to newer agents expands, physician approaches will likely evolve along these cultural lines, making mindset as critical as availability in shaping future global outcomes.