Relationship between IgM deposition intensity in renal tissue and 5-year renal prognosis in immunoglobulin A nephropathy

[Objective] This study aimed to examine both the clinical and renal tissue humoral immunodeposition profiles in immunoglobulin A nephropathy (IgAN) and identify factors influencing its prognosis. [Methods] A retrospective analysis was conducted on clinicopathological data from 774 patients with primary IgAN, confirmed via renal biopsy, at Hangzhou Hospital of Traditional Chinese Medicine between January 1, 2016, and December 31, 2018. Patients were categorized into end-event and non-end-event groups based on whether they reached the renal composite endpoint, defined as a ≥ 50% decline in eGFR or progression to end-stage renal disease (ESRD). Risk factors for adverse renal outcomes were evaluated using univariate and multivariate Cox regression models. Patients were further divided into three groups based on IgM deposition levels in the glomerular mesangial area: IgM-negative, low (IF ≤ 2+), and high (IF > 2+). Comparative analyses of clinical and histopathological characteristics, along with treatment regimens, were performed across these groups. [Results] The high IgM deposition group exhibited significantly lower serum albumin and eGFR levels, alongside higher cholesterol, 24-hour urine protein, and blood immunoglobulin M levels compared to the IgM-negative and low deposition groups. Multivariate Cox regression analysis identified immunosuppressant use as an independent protective factor for IgAN prognosis, while low serum albumin, T2 lesions, and nephropathological IgM deposits were recognized as independent risk factors for the 5-year prognosis of IgAN. Kaplan-Meier survival curves revealed that patients with high IgM deposition had markedly poorer prognoses compared to those with negative or low deposition. [Conclusion] Besides low serum albumin and T2 lesions, IgM deposition in the mesangial region emerged as an independent risk factor for the 5-year prognosis of IgAN.