Clinico-pathological features and renal outcomes of primary IgA nephropathy with IgM deposition / 中华肾脏病杂志

ABSTRACT

Objective To investigate the clinico-pathological features and renal outcomes of primary IgA nephropathy (IgAN) with glomerular IgM deposition.Methods Primary IgAN diagnosed with biopsy from January 2006 to December 2011 were recruited.Patients were divided into groups according to IgM deposition (Group A) and without IgM deposition (Group B).In addition,Group A was subdivided into two groups based on the position of IgM deposits as the mesangium (Group A1) and both mesangium and capillary wall (Group A2).Renal outcomes were defined as end stage renal disease (ESRD) and/or the doubling of baseline serum creatinine.Clinico-pathological features were retrospectively compared.Kaplan-Meier was conducted for renal outcomes,and Cox regression model was used to analyze the prognostic value of IgM deposition and the position of IgM deposition in the progression of nephropathy in IgAN patients.Results 939 patients were enrolled with 422 (44.9％) having IgM deposition (Group A).Of the 422 patients,382 patients were divided as Group A 1,whereas 40 patients were noted as Group A2.Compared to Group B,hemoglobin,serum protein,albumin and serum IgG levels in group A were significantly lower,and the cholesterol and serum IgM levels were significantly higher (all P ＜ 0.05).There was no significant difference in serum creatinine,estimated glomerular filtration rate (eGFR),urinary protein,blood pressure and uric acid between group A and B.In terms of pathological manifestations,patients in Group A exhibited more severe histological lesions including glomerular sclerosis,S1,M1 and interstitial inflammatory cell infiltration (all P＜0.05).Immunofluorescence showed that the proportion of IgG,C1q and Fg deposition in group A was significantly higher than that in group B (all P ＜ 0.05).By Kaplan-Meier,cumulative renal survival rate has no significant difference between Group A and B (Log-rank test x2=0.019,P=0.891).Univariate and muhivariable Cox regression analysis showed that IgM deposition had no significant effect on the renal progression in IgAN patients.Subgroup analysis showed that patients in Group A2 exhibited higher urine protein,creatinine and blood pressure,and lower eGFR and serum albumin,also had worse histological lesions including M1,E1 and T1-2 of Oxford classification (all P＜0.05),Immunofluorescencc showed that the proportion of IgG,C1q and Fg deposition in group A2 was significantly higher than that in group A1 (all P ＜ 0.05).By Kaplan-Meier,renal survival rates calculated from outcomes were lower in Group A2 (Log-rank test x2=1 8.207,P ＜ 0.001).In addition,IgM deposited both in the mesangium and capillary wall was a risk factor for renal progression of IgAN patients with IgM deposition by a univariate Cox hazards regression mode and multivariable-adjusted Cox models (HR=3.621,95％CI 1.924-6.814,P＜ 0.001;HR=2.309,95％CI 1.176-4.533,P=0.015respectively).Conclusions The IgAN patients with IgM deposition relatively had more severe clinicopathological changes,especially those with IgM deposited both in the mesangium and capillary wall.In this study,IgM deposition was not found to be an independent risk factor for the prognosis of kidney in IgAN patients.However,IgM deposited both in the mesangium and capillary wall was an independent risk factor for renal prognosis in IgAN patients with IgM deposition.