Nicolas Champtiaux 1 , 2 , Frédéric Lioté 3 , 4 , 21 , Khalil El Karoui 5 , Cécile Vigneau 6 , Corinne Miceli 7 , 21 , Emilie Cornec-Le Gall 8 , Philippe Rémy 9 , Gabriel Choukroun 10 , 11 , Fadi Fakhouri 12 , Cyril Garrouste 13 , Laurent Veillon 7 , 21 , Evangeline Pillebout 14 , Thierry Lobbedez 15 , Vincent Vuiblet 16 , Alain Wynckel 16 , Thomas Guincestre 17 , Eric Toussirot 18 , 21 , Eric Thervet 2 , 19 , Marion Rabant 20 , Alexandre Karras 2 , 19 , ∗
16 March 2020
IgA nephropathy (IgAN) can be associated with spondyloarthritis (SpA). The course of SpA-associated IgAN remains largely unknown due to the absence of large cohorts.
This retrospective study included patients with biopsy-proven IgAN and definite SpA. Kidney biopsies were centrally examined and scored according to the IgAN Oxford Classification. Thirty-two patients fulfilled the inclusion criteria, with a male:female ratio of 9:1 and median age of 27 and 37 years at SpA and IgAN diagnosis, respectively. HLA-B27 was positive in 90% of cases, and most patients (60%) presented with ankylosing spondylitis. The mean baseline estimated glomerular filtration rate (eGFR) was 84 ± 26 ml/min per 1.73 m 2, and the urine protein-to-creatinine ratio was 0.19 g/mmol.
Renal biopsy revealed frequent presence of crescents (33%) and interstitial inflammation (18%). Despite almost constant use of renin-angiotensin system inhibitors, combined with steroids in 13 of 32 patients, renal outcome was particularly poor. After a median follow-up of 5.9 years, 4 patients (12.5%) reached end-stage renal disease and 41% of patients experienced a >50% decrease of eGFR. The mean annual eGFR decline rate was −4.3 ± 6.7 ml/min per 1.73 m 2. The risk of reaching class IV or V chronic kidney disease (CKD) stage during follow-up was associated with the presence of hypertension, level of proteinuria, and baseline S- and T-scores of the Oxford.