Study Highlights Global Regional Differences in IgA Nephropathy Perspectives, Care


Data collected from parallel online surveys revealed notable differences in IgA nephropathy treatment among patients and nephrologists from the US, EU5, Japan, and China.

Meghan Weiss | Credit: Meghan Weiss on LinkedIn

Meghan Weiss

Credit: Meghan Weiss on LinkedIn

Findings from a recent study are calling attention to differences in perspectives about and approaches to IgA nephropathy (IgAN) treatment among nephrologists in different global regions.1

Data from 730 nephrologists in the US, EU5, Japan, and China for more than 1500 of their most recently seen patients revealed that although prognostic and predictive tools were widely available and utilized, the reliability and correlation between results, lab values, and disease progression varied from region to region.1

In 2023, budesonide (Tarpeyo) delayed-release capsules became the first treatment to earn full US Food and Drug Administration approval for reducing the loss of kidney function in adults with primary IgAN.2 Beyond the US, the 2021 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend initial management with supportive care for patients with IgAN, including lifestyle modification, blood pressure control, and maximum tolerated RAS blockade. It also recommends regularly assessing risk of disease progression, with high risk currently defined as persistent proteinuria >1 g/d despite 3 months of stable optimized supportive care.3 However, adherence to these recommendations and potential variations in care from region to region are not fully understood.

To compare IgAN treatment approaches in 4 regions of the world, Meghan Weiss, franchise head of nephrology at Spherix Global Insights, and colleagues collected information in partnership with 730 nephrologists who submitted chart data from 1570 of their most recently seen patients with IgAN through parallel online surveys in 2023. The resulting sample was representative of nephrologists and patients from the US; UK; Germany; Italy; France; Spain; Japan; and China.1

Results showed that regardless of geographic location, audited patient charts indicated hypertension, hyperlipidemia, obesity, and diabetes were the leading comorbid conditions among patients with IgAN. Investigators pointed out patients from Japan were the healthiest among the 4 regions assessed in the study, with 44% having no comorbid conditions versus 28% in EU5, 25% in China, and 18% in the US. In line with this finding, nephrologists from Japan perceived 79% of their IgAN patients to be in “excellent” overall health.1

Audited records also revealed patients in Japan and China were referred to nephrology care earlier in their CKD progression as measured by estimated glomerular filtration rate (eGFR) levels, with more than 50% of patients referred to their current nephrologist in CKD stages 1 or 2, compared to approximately 35% of patients in the US and EU5.1

Nephrologists from China (59%) and the US (53%) were most likely to agree that it is easy to identify IgAN patients who are likely to have rapid progression, whereas 43% of those in EU5 and 40% of those in Japan agreed. Investigators pointed out nephrologists from Japan ordered labs more frequently than nephrologists from other global regions. On average, patients from Japan had blood work and urinalysis labs conducted 6 times within the past 12 months versus 4 in the other regions.1

Investigators noted most audited patients had a calculated annual eGFR decline of ≥ 1 ml/year. Specifically, they observed that patients from China more frequently experienced IgAN progression (77%), whereas patients from Japan were the least likely to experience disease progression (41%). Regarding progression to end-stage renal disease, US nephrologists projected the lowest percentage of IgAN patients to eventually reach this stage (66%) compared with 73% in Japan, 75% in EU5, and 85% in China.1

Across all regions, most participating nephrologists reported closely adhering to the KDIGO guidelines when treating their patients with IgAN. While nearly all audited patients were on baseline therapy with ACE inhibitors or ARBs, the uptake of SGLT2 inhibitors was most notable in China (44%), the US (43%), and EU5 (43%), with Japan (33%) trailing in current treatment rates. However, investigators observed greater rates of corticosteroid use in patients from Japan (65%) and China (59%) compared to those from the EU5 (51%) and the US (43%), also noting a greater prevalence of tonsillectomies in patients from Japan (45%) versus other regions.1

Of note, at the time of fielding, budesonide was available to prescribe in the US and Germany with 9% and 7% of patients currently on treatment, respectively. However, investigators noted sparsentan had not yet been approved in any regions.1

“The comparison of patient chart data across various regions reveals differences in perspectives and IgAN treatment approaches among nephrologists,” investigators concluded.1 “Prognostic and predictive tools are available and utilized globally, but the reliability and correlation between results, lab values, and disease progression calls for better education and alignment of global treatment guidelines.”


  1. Dudzenski C, Weiss M, #2954 A comparative view of IgA nephropathy care across four global regions. Nephrology Dialysis Transplantation, Volume 39, Issue Supplement_1, May 2024, gfae069–1253–2954,
  2. Brooks, A. FDA Awards Full Approval to Budesonide (Tarpeyo) in Treatment of IgA Nephropathy. HCPLive. December 20, 2023. Accessed June 11, 2024.
  3. KDIGO. Takeaways for Clinicians from the KDIGO 2021 Clinical Practice Guideline for the Management of IgA Nephropathy. Accessed June 11, 2024.
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