Association between the atherogenic index of plasma and prognosis in kidney transplant recipients: a retrospective cohort study.

OBJECTIVE: End-stage kidney disease (ESKD) remains a major global health burden. Although advances in surgery, immunosuppression, and dialysis have improved short-term graft survival after kidney transplantation, long-term outcomes remain unsatisfactory. The atherogenic index of plasma (AIP), a marker of insulin resistance and atherosclerotic risk, has been widely studied in the general population and dialysis patients, but its prognostic value in kidney transplant recipients is unclear. This study evaluated the association between AIP and post-transplant outcomes. METHODS: In this retrospective cohort study, kidney transplant recipients treated at Shulan (Hangzhou) Hospital in 2019 were included. The primary outcome was a composite endpoint assessed within 12 months after kidney transplantation, including a ≥50% decline in eGFR at 3 months after transplantation, graft failure within 12 months after transplantation, or all-cause mortality within 12 months after transplantation. Cox proportional hazards regression and restricted cubic spline analyses were performed to evaluate the association between AIP and composite outcomes. Longitudinal eGFR trajectories were assessed using linear mixed-effects models and generalized estimating equations based on available postoperative eGFR measurements. RESULTS: Among 311 recipients, spline analysis showed a positive nonlinear association between AIP and adverse outcomes, with an inflection point at 0.25. During the 12-month clinical outcome assessment period, 38 composite outcome events were recorded, including ≥50% decline in eGFR at 3 months after transplantation, kidney allograft failure, or all-cause mortality. The primary Cox analysis focused on these early composite adverse outcomes within 12 months after transplantation. In addition, longitudinal eGFR trajectories were evaluated as a complementary analysis using repeated eGFR measurements collected during up to 72 months of follow-up. When AIP was analyzed as a continuous variable, each SD increase in AIP was associated with a higher risk of adverse outcomes after multivariable adjustment (HR=1.89, 95% CI 1.24-2.89). Given the nonlinear association observed in RCS analysis, AIP was additionally categorized using the identified threshold of 0.25. Compared with the low-AIP group, patients with AIP >0.25 had an increased risk of adverse outcomes (HR=2.14, 95% CI 1.01-4.54). Kaplan-Meier analysis showed lower survival in the high-AIP group. CONCLUSION: An AIP greater than 0.25 is an independent predictor of unfavorable outcomes after kidney transplantation, but shows no significant association with long-term eGFR trajectories.