Association between serum ferritin levels and risk of cardiovascular composite endpoint events in peritoneal dialysis patients: a retrospective cohort study

Background and objectives Iron metabolism abnormalities are prevalent among end-stage renal disease (ESRD) patients. However, evidence regarding the association between iron status and cardiovascular outcomes, particularly in peritoneal dialysis (PD) patients, remains limited and inconsistent. This retrospective cohort study aimed to investigate the relationship between serum ferritin levels and the risk of cardiovascular composite endpoint events in PD patients. Methods We conducted a single-center retrospective cohort study involving adult patients undergoing continuous ambulatory peritoneal dialysis (CAPD) for ≥ 3 months between January 1, 2017 and December 31, 2024. Serum ferritin levels were measured at 3 months (± 1 month) after CAPD initiation to reflect stable iron status. Participants were stratified into four groups based on baseline serum ferritin quartiles. Multivariable Cox proportional hazards regression models and restricted cubic spline (RCS) analyses were used to evaluate the association between serum ferritin levels and cardiovascular composite endpoints. Results A total of 418 patients were enrolled, with a median follow-up of 33 months (IQR: 16–54). During this period, 48 (11.5%) composite endpoint events occurred, including 20cases (41.7%) of hospitalization for congestive heart failure and 28cases (58.3%) of cardiovascular death. Multivariable Cox regression analysis revealed that, in the fully adjusted model, the risk of composite endpoint events was significantly higher in the highest ferritin quartile (Q4) compared to the lowest quartile (Q1) (HR = 1.84, 95% CI 1.33–2.56, P < 0.001). When analyzed as a continuous variable, serum ferritin was also associated with increased risk (HR = 1.97, 95% CI 1.40–2.76, P < 0.001) Trend tests across all models were significant ( P < 0.001). Fully adjusted RCS regression models indicated a positive linear association between serum ferritin levels and the risk of cardiovascular composite endpoints ( P for nonlinearity = 0.381). Subgroup analyses confirmed the consistency of this positive correlation across all predefined subgroups, with no significant interaction effects (all P for interaction > 0.05). Conclusions Serum ferritin levels are positively and linearly associated with the risk of cardiovascular composite endpoints in PD patients, suggesting its potential value as a predictive biomarker for these events.