Association Between the Planetary Health Diet Index and Chronic Kidney Disease Prevalence and Mortality: An Analysis of NHANES 2005–2018

Diet is an important determinant of chronic kidney disease (CKD). The EAT-Lancet Commission proposed the Planetary Health Diet (PHD) in 2019, and the Planetary Health Diet Index (PHDI) was developed in 2021 to quantify adherence. The index includes 16 food-group components (e.g., nuts, red meat). However, few studies have assessed associations between the PHDI and its subcomponents with CKD prevalence and CKD-related mortality. We used survey-weighted multivariable logistic regression to assess associations between the PHDI and CKD prevalence, kidney function (estimated glomerular filtration rate, eGFR), and albuminuria; Cox proportional hazards models were used to evaluate CKD-related mortality. Potential nonlinear dose-response was evaluated using restricted cubic splines and segmented regression. Predictive discrimination was quantified using time-dependent receiver operating characteristic (ROC) curves. We analyzed associations between PHDI subcomponents and CKD prevalence and CKD-related mortality. Among 31,703 adults, a higher PHDI was associated with lower CKD prevalence and CKD-related mortality. Associations were nonlinear with a threshold. The conventional ROC curve exhibited good discrimination for CKD prevalence, and the time-dependent ROC curve showed robust prognostic discrimination for CKD-related mortality. A higher PHDI was correlated with lower albuminuria levels and less impaired kidney function; nuts, vegetables, and legumes exhibited consistent protective effects. Greater PHDI adherence was linked to lower CKD prevalence, better kidney function, and reduced CKD-related mortality. Restricted cubic spline analyses revealed nonlinear patterns, with prevalence inflection at ~64 and a mortality threshold of ~47. Clinically, these thresholds may guide dietary recommendations, emphasizing increased intake of nuts, vegetables, and legumes.