Contribution of family Support, illness perception, and psychological factors to fluid management behaviors in peritoneal dialysis patients

Optimal fluid management is critical for reducing mortality in patients on peritoneal dialysis (PD). However, nonadherence to fluid restrictions remains prevalent and may be influenced by several factors. This study investigated the associations among psychosocial variables, family support, and fluid management behaviors in PD patients, and to examine potential mediation effects. In this cross-sectional study, 314 adult PD patients from a tertiary hospital in China were assessed using validated questionnaires on fluid management behaviors, depression, anxiety, illness perception, and family support. Sociodemographic and clinical data were collected from medical records. Multivariable linear regression identified predictors of fluid management behaviors. Mediation analyses explored the indirect effects of anxiety, depression, and illness perception on the relationship between family support and fluid management. A quasi-Bayesian approach was employed to estimate the direct, indirect, and total effects with 95% confidence intervals (95% CI). Higher family support (β = 0.59, 95% CI 0.44-0.73, P < 0.001), better dietary management, and shorter dialysis vintage were independently associated with superior fluid management behaviors, whereas higher anxiety (β = -0.15, 95% CI -0.27 to -0.03, P = 0.016) and negative illness perception (β = -0.17, 95% CI -0.22 to -0.11, P < 0.001) predicted worse outcomes. Mediation analysis indicated that anxiety, depression, and illness perception each significantly mediated the association between family support and fluid management, with illness perception accounting for the largest proportion of the effect (32.1%; 95% CI: 23.7%-42.8%). Psychological distress and illness perception partially mediate the beneficial effects of family support on fluid management in PD patients. Future longitudinal and intervention studies are needed to confirm causal pathways.