Albuminuria predicts kidney events in IgA nephropathy

Anne-Laure Faucon; Sigrid Lundberg; Stefania Lando; Julia Wijkström; Mårten Segelmark; Marie Evans; Juan-Jesús Carrero

doi:10.1093/ndt/gfae085

Albuminuria predicts kidney events in IgA nephropathy

Nephrol Dial Transplant. 2024 Apr 30:gfae085. doi: 10.1093/ndt/gfae085. Online ahead of print.

Authors

Anne-Laure Faucon^{1

2}, Sigrid Lundberg^{3

4

5}, Stefania Lando^{1

6}, Julia Wijkström^{7

8}, Mårten Segelmark^{9

10}, Marie Evans^{7

8}, Juan-Jesús Carrero^{1

4}

Affiliations

¹ Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
² Department of Clinical Epidemiology, Centre for Research in Epidemiology and Population Health, INSERM U1018, Paris-Saclay University, France.
³ Department of Medical Specialist Care, Nephrology Clinic, Danderyd University Hospital, Stockholm, Sweden.
⁴ Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden.
⁵ MedTechLabs, BioClinicum, Karolinska University Hospital, Solna, Sweden.
⁶ University of Milano-Bicocca, Milan, Italy.
⁷ Department of Nephrology, Karolinska University Hospital, Stockholm, Sweden.
⁸ Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
⁹ Department of Clinical Sciences, Lund University, Lund, Sweden.
¹⁰ Department of Endocrinology, Nephrology and Rheumatology, Skåne University Hospital, Lund, Sweden.

PMID: 38688876
DOI: 10.1093/ndt/gfae085

Abstract

Background & hypothesis: KDIGO recommends proteinuria <1 g/d as a treatment target in patients with immunoglobulin A nephropathy (IgAN) because of high-risk of progression to kidney failure. However, long-term kidney outcomes in patients with low-grade proteinuria remain insufficiently studied.

Methods: We enrolled patients with biopsy-proven primary IgAN from the Swedish Renal Registry and analyzed associations between urine albumin-to-creatinine ratio (uACR, in categories < 0.3, ≥0.3-0.5, ≥0.5-1.0, ≥1.0-1.5, ≥1.5-2.0 and ≥ 2.0 g/g) and the occurrence of major adverse kidney events (MAKE, a composite of kidney replacement therapy [KRT] and > 30% decline in eGFR). We also explored the risk of kidney events associated with change in uACR within a year.

Results: We included 1269 IgAN patients (74% men, median 53 years, mean eGFR 33 mL/min/1.73m², median uACR 0.7 g/g). Over median follow-up of 5.5 [2.8;9.2] years, 667 MAKE and 517 KRT events occurred, and 528 patients experienced > 30% eGFR decline. Compared with uACR < 0.3 g/g, any higher uACR category was strongly and incrementally associated with the risk of MAKE (adjusted HR ranging from 1.56 [95%CI 1.14-2.14] if uACR 0.3-0.5 g/g to 4.53 [3.36-6.11] if uACR ≥ 2.0 g/g), KRT (HR ranging from 1.39 to 4.65), and eGFR decline > 30% (HR ranging from 1.76 to 3.47). In 785 patients who had repeated uACR measurements within a year, and compared with stable uACR, the risk of kidney events was lower if uACR decreased by 2-fold (HR ranging from 0.47 to 0.49), and higher if uACR increased by 2-fold (HR from 1.18 to 2.56), irrespective of baseline uACR.

Conclusions: There is substantial risk of adverse kidney outcomes among patients with IgAN and uACR between 0.3 and 1.0 g/g, a population currently considered at low-risk of CKD progression. Reduction in uACR is associated with better kidney outcomes, irrespective of baseline uACR.

Keywords: IgA nephropathy; albuminuria; chronic kidney disease; kidney replacement therapy.