This week in Nephrology

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Welcome to This Week in Nephrology. This week we're covering 10 notable papers spanning albuminuria and the endpoints we use to judge kidney therapies, dialysis care and transplant access, and a pair of studies on perioperative kidney injury and rare glomerular disease. Let's dive in.

A thread running through several papers this week is how the field measures whether a kidney therapy is working, and albuminuria sits at the centre of that conversation. In the American Journal of Kidney Diseases, Rashid, Heerspink and Inker review the case for albuminuria as both a risk marker and a treatment target [1]. They lay out the epidemiology showing a continuous, graded link between baseline albuminuria, and changes in it, with later kidney failure, cardiovascular events and death. The headline figure from trial-level meta-analysis is that a treatment effect of at least a thirty percent fall in the urine albumin-to-creatinine ratio corresponds to roughly a twenty percent benefit on chronic kidney disease progression. The authors argue that residual albuminuria on treatment flags patients at persistently high risk, and that combination therapies can push albuminuria down by more than half in selected settings, supporting a treat-to-target model built on serial measurement. This is a narrative review, so it frames the argument rather than proving that targeting a number improves outcomes. That framing matters for the next paper, in Kidney International Reports, where Korucu and colleagues ran a Bayesian network meta-analysis of 32 randomized trials covering more than twenty-one thousand patients with chronic kidney disease [2]. Every mineralocorticoid receptor antagonist dose they examined lowered albuminuria, with heavily overlapping effects, and spironolactone 25 milligrams looked similar to finerenone 20 milligrams on that measure. Hyperkalaemia rose across the class without consistent differences between steroidal and nonsteroidal agents, and adverse events were more common with longer follow-up and lower baseline kidney function. The authors position steroidal agents as accessible options where cost limits finerenone, but the evidence is indirect and rests on a surrogate endpoint; it does not show equivalent hard outcomes, and the authors themselves call for head-to-head outcome trials.

The same endpoint question surfaces in rarer diseases. Writing in the Journal of the American Society of Nephrology, Gale and colleagues review how proteinuria and filtration decline connect to kidney failure in Alport syndrome [3]. They separate proteinuria driven by podocyte dysfunction and foot-process effacement, which may be partly reversible, from proteinuria tied to podocyte loss and glomerulosclerosis, which probably is not. Biopsy markers, they argue, are currently most useful for showing target engagement, because their quantitative link to kidney failure is not yet defined, and any trial endpoint framework has to account for genotype, sex, age and the nonlinear course of the disease. And in Kidney International, Brix and colleagues report from a European Vasculitis Society focus group on kidney endpoints in ANCA-associated vasculitis [4]. Over two years, nephrologists, pathologists and rheumatologists catalogued the wide variation in how trials define active kidney disease, response, remission, relapse, recovery and kidney failure, and they offer an expert proposal and research agenda ahead of a formal Delphi consensus. Neither paper changes bedside care today, but together with the albuminuria review they show a field trying to agree on what counts as success before the next generation of drugs arrives.

Turning to dialysis, two papers address how treatment choices play out in individual patients. In the Clinical Journal of the American Society of Nephrology, Cromm and colleagues report a prespecified subgroup analysis of the CONVINCE trial, which compared high-volume post-dilution hemodiafiltration of at least 23 litres per session with high-flux hemodialysis [5]. Among 1211 participants with patient-reported outcome data followed for a median of about two and a half years, the effects on eight PROMIS domains were broadly consistent across age, sex, diabetes, cardiovascular disease, dialysis vintage, access type and residual urine output. A handful of nominal interactions appeared, but they were small, unadjusted for multiple comparisons and inconsistent across related domains. The authors are explicit that these findings should not be used to select or exclude patients for hemodiafiltration on the basis of patient-reported outcomes. In Nephrology Dialysis Transplantation, Beige, Hecking and colleagues take a different approach to intradialytic hypotension, using five cases to describe distinct phenotypes [6]. Two are acute, an allergic reaction to dialyzer material and an autonomic, postprandial pattern, and three are chronic, namely hypovolaemia from an overly ambitious target weight, a mismatch between ultrafiltration and vascular refilling despite fluid overload, and limited cardiac reserve. Their point is that the chronic phenotypes look alike at the chair yet call for opposite corrections, which makes objective volume assessment the decisive first step, and that the real concern is organ hypoperfusion rather than the blood pressure number. This is expert opinion built on cases, and the authors' main research ask is for future trials to enrol phenotype-defined populations and measure hard outcomes.

Transplantation brings two papers, one about policy and one about monitoring. In the Journal of the American Society of Nephrology, Drewry and colleagues examined whether Medicare's End-Stage Renal Disease Treatment Choices Model, which randomly assigned financial incentives to dialysis facilities, improved the early steps of transplant access in Georgia, North Carolina and South Carolina [7]. Among nearly twenty-seven thousand patients in 706 facilities, more than half of whom were non-Hispanic Black, the difference-in-differences estimates for timely referral, evaluation start and waitlisting or living-donor transplantation all leaned slightly positive but none reached statistical significance. The authors read this as evidence that misaligned facility incentives alone probably do not explain the model's limited effect on transplantation, and they note large pandemic-era delays in referral across both arms. In Transplantation, Sureshkumar and colleagues used the prospective multicentre Kidney Outcomes AlloSure Registry to ask whether early donor-derived cell-free DNA patterns carry prognostic meaning [8]. Among 1137 recipients, the large majority had consistently low levels over the first four months, while roughly one in ten had a transient rise, and smaller groups had late or persistent elevation. Transient elevation behaved much like consistently low values, with graft loss under three percent, whereas persistent elevation carried graft loss in about one in five recipients. Late elevation was independently linked to donor-specific antibodies, rejection and graft loss, and persistent elevation to rejection, dysfunction and loss, regardless of sensitization or retransplant status. The registry design is observational and does not test whether acting on these trajectories improves outcomes, but it supports reading the pattern of early results rather than any single value, and it suggests transient early rises, often blamed on ischaemia-reperfusion injury, may indeed be benign.

Finally, a rigorous negative trial and a descriptive series in rare glomerular disease. In the American Journal of Kidney Diseases, Garg and colleagues report the prespecified kidney substudy of the COP-AF trial, in which 2947 patients aged 55 or older having major noncardiac thoracic surgery were randomized to colchicine 0.5 milligrams twice daily for ten days or placebo [9]. Perioperative acute kidney injury occurred in under five percent of patients in each group, with no meaningful difference, and the result held across alternative definitions and in patients with pre-existing chronic kidney disease. The trial was underpowered for small effects on dialysis-requiring injury, and patients with filtration below 30 were excluded, but the masked, multinational design makes this a fairly firm null for colchicine as kidney protection in this surgical setting. Also in the American Journal of Kidney Diseases, Bu and colleagues describe 46 cases of proliferative glomerulonephritis with monotypic IgG1 deposits, a less familiar variant than the IgG3 form [10]. Among patients older than fifty, close to three quarters had a detectable clone or monoclonal immunoglobulin, often chronic lymphocytic leukaemia or small lymphocytic lymphoma, compared with only one of seventeen younger patients. Ten of twelve patients with an identified clone responded to clone-targeted therapy, the disease recurred in transplanted kidneys, and kidney failure or death reached about thirty percent at five years. This is a retrospective, single-centre series with non-standardized workup, so it informs the diagnostic search in older patients more than it defines treatment.

If you only have time for one paper this week, make it the COP-AF kidney substudy from Garg and colleagues in the American Journal of Kidney Diseases [9]. It is a large, blinded randomized trial that gives a clear negative answer to whether perioperative colchicine prevents acute kidney injury, closing a plausible anti-inflammatory hypothesis with evidence rather than speculation.

Here is what this week's evidence adds up to in Nephrology. First, albuminuria is consolidating its role as a surrogate and a treatment target, and a network meta-analysis suggests steroidal and nonsteroidal mineralocorticoid antagonists lower it similarly, though hard-outcome comparisons are still missing. Second, endpoint definitions in Alport syndrome and ANCA vasculitis remain unsettled, and consensus work is under way rather than finished. Third, CONVINCE offers no convincing signal that the patient-reported benefits of hemodiafiltration differ by subgroup, while intradialytic hypotension is being reframed as several physiologic phenotypes, so far on the basis of expert opinion. Fourth, early cell-free DNA trajectories, particularly late or persistent elevation, stratify transplant risk in registry data, and facility incentives under the Medicare model did not measurably speed transplant access in the Southeast. Fifth, colchicine did not reduce perioperative kidney injury after thoracic surgery, and in older patients with IgG1 monotypic deposits, an underlying clone is common in this single-centre experience.

That's your roundup for This Week in Nephrology. The full transcript and references are available on the episode page. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

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