Clinicopathologic and prognostic analyses in elderly patients with primary IgA nephropathy

Objective To compare the differences in clinicopathologic characteristics and prognosis between elderly and non-elderly patients with IgA nephropathy, and to explore the clinical and pathological characteristics of elderly patients with IgA nephropathy.Methods One hundred and fifty-seven patients with primary IgA nephropathy diagnosed by renal biopsy in the First Affiliated Hospital of China Medical University between January 2009 and December 2016 were enrolled in this study. Seventy-seven patients at the age of 60 years old and above were included as the elderly group, and 80 patients at the age between 14 and 59 were included as the control group. The clinical and pathological data of the included patients were collected, and comparison of the means between the groups was performed using Mann-Whitney U test.Results The elderly group had a higher incidence of hypertension and higher levels of urinary protein excretion (hypertension: 77.92% vs. 36.25%, P<0.001; urinary protein excretion: 3.08±2.92 g/day vs. 2.03±1.91 g/day, P=0.009), lower levels of estimated glomerular filtration rates (eGFR), hemoglobin, serum albumin (eGFR: 58.73±28.29 ml·min^-1·(1.73 m²)^-1 vs. 86.02±36.68 ml·min^-1·(1.73 m²)^-1, P<0.001; hemoglobin: 122.18±18.79 g/L vs. 130.41±21.27 g/L, P=0.011; serum albumin: 32.75±7.89 g/L vs. 37.26±6.41 g/L, P<0.001) than in the non-elderly group. On the pathological lesions, the elderly group had lower ratio of global and all categories of glomerulosclerosis (global sclerosis: 0.17±0.17 vs. 0.25±0.26, P=0.014; all categories of glomerulosclerosis: 0.18±0.18 vs. 0.30±0.29, P=0.003), more severe tubular-interstitial injury (expressed as the ratio of T0/T1,2) (0.75 vs. 1.29, P<0.001), a higher ratio of the glomeruli with crescents formation and a higher incidence of renal arteriole sclerosis (crescents formation: 0.11±0.23 vs. 0.05±0.05, P=0.049; arteriole sclerosis: 87.01% vs. 37.5%, P<0.001) than in the non-elderly group. During the period of follow-up, the elderly group had a higher incidence of end-stage renal disease than in the non-elderly group (15.09% vs. 3.39%, P=0.045).Conclusions The elderly patients with IgA nephropathy had more severe clinical manifestations, tubular-interstitial injury and renal arteriole sclerosis, and poorer renal prognosis in the non-elderly patients.