Association between hemoglobin levels and renal progression in patients with IgA nephropathy / 中华肾脏病杂志

ABSTRACT

Objective:To investigate the relationship between hemoglobin levels and renal prognosis in patients with IgA nephropathy (IgAN).Methods:The clinical data and pathological examination results of IgAN patients diagnosed by renal biopsy at the Second People's Hospital of Shenzhen from February 25, 2010 to September 9, 2020 were retrospectively collected and analyzed. The patients were divided into anemic group and non-anemic group according to the anemia diagnostic criteria (The hemoglobin levels were<120 g/L and<110 g/L in males and females respectively at sea level area). Endpoint event was defined as a decrease in estimated glomerular filtration rate (eGFR) of>50% from baseline and/or progression to stage 5 chronic kidney disease [eGFR<15 ml·min -1·(1.73 m 2) -1]. Cox regression analysis was used to analyze the factors affecting the poor renal prognosis. The relationship between hemoglobin and renal function prognosis was analyzed by smoothing curve fitting and threshold effect. Kaplan-Meier survival curve was used to compare and analyze the difference of renal survival rate between the anemic and non-anemic IgAN patients. Results:A total of 1 263 IgAN patients were included in this study, 255(20.19%) patients were in the anemia group and 1 008 (79.81%) patients were in the non-anemia group. The anemia group had lower body mass index, baseline eGFR, serum albumin, and triglyceride than those in the non-anemia group (all P<0.05). The proportion of females, 24 h urinary protein content, and the proportion of renal tubule atrophy/interstitial fibrosis, segmental sclerosis and crescents in the anemia group were higher than those in the non-anemia group (all P<0.05). Multivariate Cox regression analysis showed that low hemoglobin was an independent influencing factor for renal endpoint event ( HR=0.25, 95% CI 0.07-0.90, P=0.022). Smoothing curve fitting analysis and threshold effect analysis showed that a curving relationship was detected between hemoglobin and relative risk of renal endpoint event. As hemoglobin increased, there was a protective effect on renal function when hemoglobin level was lower than 147 g/L ( β=0.96, 95% CI 0.94-0.99, P=0.008). Kaplan-Meier survival curve analysis suggested that patients with anemia had a lower cumulative renal survival rate than that of patients without anemia (Log-rank test χ2=10.106, P=0.002). Conclusions:Low hemoglobin is an independent influencing factor for poor prognosis of renal function in IgAN patients. Cumulative renal survival rate is lower in IgAN patients with anemia than that of patients without anemia.