Clinical and Prognostic Factors in Patients with IgG4-Related Kidney Disease.

Abstract

IgG4-related kidney disease is a major manifestation of IgG4-related disease, a systemic fibro-inflammatory disorder. However, the clinical and prognostic kidney-related factors in patients with IgG4-related kidney disease are insufficiently defined. We conducted an observational cohort study using data from 35 sites in two European countries. Clinical, biological, imaging and histopathological data, treatment modalities, and outcomes were collected from medical records. Logistic regression was performed to identify the possible factors related to an eGFR ≤30 mL/min/1.73 m2 at the last follow-up. Cox proportional hazards model was performed to assess the factors associated with the risk of relapse. We studied 101 adult patients with IgG4-related disease with a median follow-up of 24 (11-58) months. Of these, 87 patients (86%) were male, and the median age was 68 (57-76). Eighty-three patients (82%) had IgG4-related kidney disease confirmed by kidney biopsy, with all biopsies showing tubulointerstitial involvement and 16 showing glomerular lesions. Ninety patients (89%) were treated with corticosteroids and 18 (18%) received Rituximab as first-line therapy. At the last follow-up, the eGFR was below 30ml/min/1.73m2 in 32% of patients; 34 (34%) experienced a relapse, while 12 (13%) had died. By Cox survival analysis, the number of organs involved (HR=1.26, CI 95% [1.01-1.55]), low C3 and C4 concentrations (HR=2.31, CI 95% [1.10-4.85]) were independently associated with a higher risk of relapse, whereas first-line therapy with Rituximab was protective (HR=0.22, CI 95% [0.06-0.78]). At their last follow-up, 19 patients (19%) had an eGFR ≤30ml/min/1.73m2. Age (OR=1.11, CI 95% [1.03-1.20]), peak serum creatinine (OR=2.74, CI 95% [1.71-5.47]), and serum IgG4 level ≥5g/L (OR=4.46, CI 95% [1.23-19.40]) were independently predictive for severe chronic kidney disease. IgG4-related kidney disease predominantly affected middle-aged males and manifested as tubulointerstitial nephritis with potential glomerular involvement. Complement consumption and the number of organs involved were associated with a higher relapse rate, whereas first-line therapy with Rituximab was associated with lower. Patients with high serum IgG4 concentrations (≥5g/L) had more severe kidney disease.