Exploring vaccination adherence and its determinants in kidney transplant recipients: insights from a large italian transplant centre

Background: Vaccine-preventable infections are a major cause of morbidity and mortality among kidney transplant recipients, yet real-world adherence to recommended vaccination schedules remains poorly characterised. We aimed to assess adherence to the full vaccination schedule and identify its independent predictors in a large Italian cohort. Methods: Single-centre retrospective cohort study of consecutive adult kidney transplant recipients at the University Hospital of Padua (Veneto, Italy), 2013-2024. Adherence was assessed on the regional immunisation registry data and quantified using a composite vaccination adherence score encompassing up to ten vaccines according to patient-specific elegibility ranging from 0 (adherent to no vaccination) to 1 (adherent to all vaccinations). Determinants were analysed by fractional logit regression (quasi-binomial GLM, logit link, HC1 robust standard errors); sensitivity analyses excluded influential observations by Cook's distance. Results: Among 784 recipients (mean age 52.9 ± 12.3 years; 63.7% male), median adherence score was 0.25 (IQR 0.13-0.44) and only 11 patients (1.4%) were fully adherent. Per-vaccine adherence was highest for COVID-19 (87.4%) and HBV (61.9%), and lowest for Hib (7.9%), MenB (9.0%), HPV (13.1%), and RZV (13.8%). In the multivariable model, transplant in 2023-2024 (aOR 1.53, 95%CI 1.25-1.89; p < 0.001) and older age (aOR 1.01/year, 95%CI 1.00-1.02; p = 0.030) were independently associated with higher adherence, whereas unknown underlying renal pathology (aOR 0.77, 95% CI 0.62-0.96; p = 0.02) and re-transplantation (aOR 0.73, 95%CI 0.56-0.95; p = 0.02) predicted lower adherence. Findings were robust in sensitivity analyses. Conclusions: Vaccination adherence was suboptimal, with patients with unknown renal pathology representing a particularly vulnerable subgroup. Temporal improvement closely aligned with regional guideline publication suggests that structured guideline implementation can meaningfully improve adherence.