Atherogenic index of plasma and lower estimated glomerular filtration rate in IgA nephropathy

IgA nephropathy (IgAN) demonstrates substantial progression to end-stage kidney disease, yet metabolic risk factors remain underexplored. The atherogenic index of plasma (AIP), calculated as log(triglycerides/HDL-cholesterol), integrates pro-atherogenic and anti-atherogenic lipid components, but its association with renal function in IgAN is unclear. This cross-sectional study analyzed 1186 Chinese patients with biopsy-proven primary IgAN. AIP was standardized as Z-scores for analysis. Primary outcome was estimated glomerular filtration rate (eGFR). Secondary outcomes included eGFR < 60 mL/min/1.73 m² and proteinuria. Multivariable linear and logistic regression models assessed associations with progressive adjustments. Subgroup analyses evaluated effect modification. Median age was 34 years with 48% males. Each standard deviation increase in AIP was associated with 2.08 mL/min/1.73 m² lower eGFR (95% CI: -3.48, -0.68; p = 0.004) and 33% higher odds of eGFR < 60 mL/min/1.73 m² (OR: 1.33; 95% CI: 1.07, 1.67; p = 0.012) in fully adjusted models. Patients in the highest versus lowest AIP tertile had 4.73 mL/min/1.73 m² lower eGFR (p = 0.005) and 76% higher odds of eGFR < 60 mL/min/1.73 m² (p = 0.034). AIP was associated with higher proteinuria in patients with eGFR ≥ 60 mL/min/1.73 m² (β: 141.63 mg/24 h per SD; 95% CI: 33.75, 249.51; p = 0.01). Significant effect modification occurred by BMI (p-interaction = 0.032) and hyperuricemia (p-interaction = 0.030), with stronger associations in patients with BMI < 23 kg/m² and without hyperuricemia. Higher AIP independently associates with lower eGFR and higher proteinuria at diagnosis in IgAN patients, particularly in specific metabolic subgroups. Longitudinal studies are needed to determine whether AIP has prognostic value for renal outcomes.