A comparative study on the clinicopathological features and short-term prognosis of IgA-dominant infection-related glomerulonephritis and IgA nephropathy.

BACKGROUND

IgA-dominant infection-related glomerulonephritis (IgA-IRGN) and primary IgA nephropathy (IgAN) share similar clinicopathological features, making differentiation challenging despite distinct therapeutic strategies. This study compares the clinicopathological characteristics and short-term prognoses of the two conditions to identify diagnostic differentiators.

METHODS

This retrospective study included patients diagnosed with IgA-IRGN (n = 30) and IgAN (n = 120). We comparatively analyzed their clinical and pathological features, as well as the short-term prognostic differences. Univariate and multivariable logistic regression analyses were conducted to evaluate independent associations. Different pathological scoring systems were utilized to assess their diagnostic value. Short-term prognosis was evaluated at a 6-month follow-up, based on changes in the estimated glomerular filtration rate (eGFR) and the remission rate of proteinuria.

RESULTS

Compared to IgAN, IgA-IRGN patients had higher mean arterial pressure, incidences of edema, acute kidney injury (AKI), and hypertension. Serum albumin, eGFR, and complement C3 were lower, while 24-hour proteinuria, neutrophil-to-albumin ratio (NAR), and neutrophil-to-C3 ratio (NC3r) were higher. Pathologically, IgA-IRGN showed diffuse endocapillary hypercellularity (100% vs. 2.5%) and universal subepithelial "hump-like" deposits (100% vs. 0.89%). Multivariable analysis revealed hypocomplementemia C3, AKI, and serum albumin could serve as non-invasive differentiating indicators. After incorporating pathological factors, hypocomplementemia C3, the Lupus Nephritis Activity Index (AI) score, and diffuse foot process effacement emerged as independent differentiating factors. IgA-IRGN patients demonstrated better short-term renal function recovery and higher proteinuria remission rate (P < 0.05).

CONCLUSIONS

Significant clinicopathological differences exist between IgA-IRGN and IgAN. Hypocomplementemia C3, AKI, low serum albumin, diffuse foot process effacement, and the AI score were independent indicators for differentiation. IgA-IRGN patients experience better short-term renal recovery and proteinuria remission than IgAN patients.