Abstract:

Objective To investigate the impact of body mass index (BMI) on the clinicopathology and prognosis of patients with IgA nephropathy (IgAN). Methods The clinicopathological data and prognosis of 533 primary IgAN patients who were diagnosed by renal biopsy in the Affiliated Hospital of Qingdao University from February 2013 to May 2021 were retrospectively analyzed.Serum creatinine levels doubling and/or entered end-stage renail disease(ERSD) and/or renal replacement therapy and/or death were endpoints.According to the BMI and World Health Organization (WHO) obesity classification, the patients were grouped as follows: low body weight group (BMI<18.5 kg/m²), normal weight group (18.5≤BMI<25.0 kg/m²) and overweight obese group (BMI≥25.0 kg/m²). The differences in clinicopathological and prognosis of of patients in each group were compared.The Kaplan-Meier survival curve was used to assess the cumulative renal survival rate of patients, and the multifactorial Cox regression analysis was used to analyze the risk factors affecting the renal prognosis of IgAN patients with overweight and obesity. Results In 533 IgAN patients, 19 patients (3.6%) were underweight, 267 patients (50.1%) were normal weight, and 247 patients (46.3%) were obese weight. Compared with low body weight group and normal weight group, the overweight obese group showed increased age, systolic blood pressure (SBP), diastolic blood pressure (DBP), angiotensin-converting-enzyme inhibitors(ACEI)/angiotensin II receptor type 1(ARB)use ratio, hemoglobin, 24-hour urinary protein excretion, triglycerides, fasting plasma glucose, blood complement C3 and C4 levels, and uric acid, and decreased HDL-C and eGFR levels (all P<0.05). In comparison of normal group and low group, normal group displayed increased age, SBP, DBP, ACEI/ARB use ratio, uric acid, and decreased eGFR (all P<0.05). LDL-C levels were higher in both the overweight obese group and the normal group than in the low group (all P<0.05). IgM levels were lower and male prevalence and CRP levels were higher in the overweight obese group compared with the normal group (all P<0.05). Neutrophil counts were higher in the low group than in the normal group (P<0.05). In light microscopic examination, low group showed decreased the degree of vascular damage and inflammatory cell infiltration among three groups (all P<0.05). Mesangial deposition of C3 was weakened in the overweight obese group compared with the normal group (P<0.05). Kaplan-Meier survival curve analysis showed that the cumulative renal survival rate was higher in the normal group than in the overweight obese group (Log-rank test, χ ²=8.702, P=0.003), whereas, which was higher in the overweight obese group than in the low group (Log-rank test, χ ²=4.624, P=0.032). 5-year renal survival rates were 69.8%, 75.6%, and 85.9%, for low group, overweight obese group and normal group respectively, with higher 5-year renal survival rates in the normal group than in the overweight obese group (Log-rank test, χ ²=4.996, P=0.025), and higher 5-year survival rates in the overweight obese group than in the low group (Log-rank test, χ ²=5.764, P=0.016). The multifactorial Cox regression analysis showed that 24-hour urinary protein excretion, triglycerides, and hemoglobin were risk factors for endpoint events in IgAN patients with overweight obese.Conclusion Among the IgAN patients, the clinical manifestations of overweight and obesity patients are worst characterized by severer vascular damage and inflammatory cell infiltration, poorer renal prognosis. Thus the therapeutic effect of those patients and follow-up lifestyle and weight management should be emphasized.

Key words: glomerulonephritis, IGA, body mass index, pathology, prognosis