Aspirin for the Prevention of Transplant Renal Artery Stenosis: The Role of Age Factor

Abstract Transplant renal artery stenosis (TRAS) is a potentially serious complication following kidney transplantation. Low-dose aspirin has been proposed as a preventive strategy due to its antiplatelet and vascular protective effects. In this study, we retrospectively analyzed kidney transplant recipients at our center from January 2018 to December 2021. Patients were categorized into an aspirin group (n = 169) and a control group (n = 232). Initially diagnosed TRAS (id-TRAS) was diagnosed by Doppler ultrasound; confirmed TRAS (c-TRAS) by digital subtraction angiography. Id-TRAS incidence was similar between groups (14.20% vs. 15.95%), but c-TRAS was significantly lower with aspirin (2.96% vs. 7.76%; P = 0.041). ROC analysis identified 38 years as the optimal cutoff for TRAS risk,and patients were divided into two groups: ＜ 38 years and ≥ 38 years.After controlling for ages, the incidence of c-TRAS showed a statistically significant difference (P = 0.028). After controlling for aspirin use, the incidence rates of id-TRAS and c-TRAS differed significantly across age groups (P = 0.001; P ＜ 0.001). Kaplan-Meier analysis demonstrated that patients aged ＜ 38 years receiving aspirin had the lowest cumulative risk for both id-TRAS and c-TRAS, with statistically significant intergroup differences (log-rank P = 0.016; P = 0.006). Univariate Cox regression identified several risk factors for TRAS. Subsequent multivariate Cox regression revealed that aspirin use reduced the risk of id-TRAS and c-TRAS by 56% (HR = 0.44, 95% CI: 0.26 - 0.76, P = 0.003) and 73% (HR = 0.27, 95% CI: 0.10 - 0.74, P = 0.011), respectively. In contrast, age ≥ 38 years conferred a 1.91-fold and 2.84-fold increased risk for id-TRAS (HR = 1.91, 95% CI: 1.13 - 3.22, P = 0.015) and c-TRAS (HR = 2.84, 95% CI: 1.18 - 6.81, P = 0.020). Bleeding events were more frequent in the aspirin group (P = 0.016), with lower platelet aggregation at 3 months (P ＜ 0.001). In conclusion, low-dose aspirin appears to lower the incidence of c-TRAS, especially in younger recipients, while predisposing older patients to a higher risk of bleeding. These results emphasize the importance of individualized risk-benefit evaluation in clinical decision-making.