Objective: BK virus (BKV) infection is a significant concern for kidney transplantation (KT) recipients, potentially leading to nephropathy and graft loss, particularly under intensive immunosuppression. This study investigates the prevalence of BKV infection and its associated risk factors following KT.
Materials and Methods: We conducted a retrospective cohort study on 322 KT recipients undergoing routine follow-up in our unit. BKV infection was defined as either high-level BK viruria (BKV DNA load in urine ≥10⁷ copies/mL) or BKV-associated nephropathy. Risk factors were assessed using univariate and multivariate Cox regression analyses.
Results: BKV infection was diagnosed in 9.6% (n=31) of patients, with a median onset of 8.7 months (range: 3.02–31.4). Recipients with BK virus infection were more likely to have received kidneys from non-relative living donors (p=0.005). Smoking and calcineurin inhibitor treatment were more prevalent among infected patients compared to those without BKV infection (p=0.015 and p=0.034, respectively). Additionally, BKV-infected patients experienced higher rates of acute rejection episodes (p=0.009) and all-cause allograft loss (p=0.009). In univariate analysis, smoking (hazard ratio [HR]: 2.697, p=0.007), diabetes mellitus (HR: 2.207, p=0.082), non-relative living donors (HR: 4.355, p=0.001), and induction therapy with anti-thymocyte globulin (ATG) (HR: 2.146, p=0.082) were identified as potential risk factors for infection. Smoking and non-relative living donors were independent risk factors for BKV infection (HR: 2.100, p=0.046 and HR: 4.243, p=0.019, respectively).
Conclusion: While immunosuppressive therapy is a well-recognized risk factor for BKV infection, our study highlights smoking and non-relative living donors as independent risk factors. Close monitoring of high-risk recipients and smoking cessation counseling should be prioritized to mitigate BKV infection risk.