Kidney involvement was reported in 49% to 79% of adults with IgA vasculitis, according to a new evidence review and expert guideline. The guidance says an estimated glomerular filtration rate, or eGFR, below 60 ml/min/1.73 m2 and proteinuria, or protein in the urine, above 0.5 g/g were associated with progression to kidney failure. In a retrospective French cohort of 250 adults with biopsy-confirmed kidney involvement, 38% developed chronic kidney disease and 11% progressed to kidney failure over a median 14.8 years.
Those long-term figures do not represent every adult with IgA vasculitis: the cohort included people whose kidney involvement had been confirmed by biopsy. The review presents the kidney risk markers as observational associations, so they should not be read as proof that either marker causes kidney failure.
Diagnosis needs several pieces of evidence
The guideline does not treat any single adult feature as enough to settle the diagnosis. It recommends combining clinical signs, laboratory results and histological findings. Predominant IgA deposits alongside compatible histology support the diagnosis, but absent IgA deposits do not by themselves exclude IgA vasculitis.
The revised Ankara criteria are presented as classification tools, not diagnostic rules. Across two independent cohorts, their sensitivity, a measure of how many relevant cases they captured, ranged from 76% to 97.8%. Specificity, which reflects how well the criteria excluded cases that did not fit, ranged from 85.0% to 94.5%. The paper notes that performance varied between cohorts.
When a kidney biopsy enters the picture
The recommendations call for a kidney biopsy when the diagnosis is uncertain, when eGFR falls by more than 30% in one to two weeks, or when proteinuria above 0.5 g/g persists for two to four weeks. They also recommend the Oxford MEST-C system for classifying kidney tissue findings.
Treatment remains the unsettled part
Treatment is the least settled part of the framework. The review describes the evidence as poorly defined, with most knowledge coming from observational studies and limited randomized, prospective or retrospective controlled data. That mix leaves comparative recommendations and the optimal regimen uncertain.
In the prospective randomized CESAR trial, adding cyclophosphamide to glucocorticoids brought no reported benefit. The severe gastrointestinal subgroup had only 15 patients, which precluded meaningful subgroup analysis.
Rituximab results looked favorable, but they do not provide a conclusive answer. In a multicentre Italian observational study of 22 adults with adult-onset IgA vasculitis, remission was reported in 91% after six months. Kidney function remained stable and proteinuria decreased approximately fivefold after a median 24 months. Because the study was observational and uncontrolled, with possible selection bias, it cannot establish that rituximab caused those outcomes.
A post-review analysis designed to approximate a clinical trial, using propensity-score matching, included 368 patients in each treatment group. Rituximab was associated with a 35% lower risk of kidney failure or chronic kidney disease stages II to V, although indication bias remained possible.
A schedule for watching the kidneys
The guideline proposes monitoring every 1 to 3 months during the first year and every 6 to 12 months thereafter, including renal tests. It says the interval should be tailored to the clinical course. The evidence basis for this schedule is largely expert consensus.
Built from a broad review, with clear limits
The project combined a systematic literature review with a two-round Delphi consensus process. Guideline development followed the RIGHT reporting statement and used a core committee and a voting panel. The panel added 23 experts, a specialist vasculitis nurse, a patient representative and two project fellows to the core committee; 37 experts were finally consulted.
Two fellows searched PubMed, Embase and the Cochrane Central Register of Controlled Trials for relevant publications from 1970 through 27 November 2025. The search yielded 3,784 articles, of which 335 were included in guideline development.
Of 21 initial Delphi questions, 14 met the threshold to be carried into the literature review. Positive consensus required more than 75% of respondents to assign scores from 7 to 9. Final recommendations were accepted when more than 80% of voting panel members assigned a score of at least 8 out of 10. The framework used evidence levels from 1a to 5 and recommendation grades from A to D.
The framework offers a structured starting point, but its strength is constrained by the evidence base. The highest evidence level and recommendation grade were 2B and B, reflecting few high-quality randomized trials and meta-analyses. European representation may limit the framework's global generalizability, while treatment recommendations still depend heavily on observational evidence.
The result is guidance that can organize diagnosis, kidney assessment and follow-up, while comparative treatment questions remain open. The review points to the need for more randomized studies and better evidence for treatment, especially in IgA vasculitis with nephritis.
Paper data and sources
Original title: Evidence-based guidelines for the diagnosis and management of adult-onset IgA vasculitis.
Authors: Alexandra Audemard-Verger, Evangéline Pillebout, Eva Baier et al.
Journal/Repository: Nature reviews. Rheumatology
Status: Peer-reviewed
First online: 2026-08-20
DOI: 10.1038/s41584-026-01420-3
Original paper · Full text