Association between planetary health diet and prognosis in patients with advanced cardiovascular-kidney-metabolic syndrome

Background Diet plays a critical role in human health and environmental sustainability, particularly in the development of the cardiovascular, kidney, and metabolic (CKM) diseases. However, the association between the Planetary Health Diet Index (PHDI) and prognosis and in individuals with established CKM diseases remain unknown. Purpose This study aimed to assess the association between the PHDI and risk of mortality in individuals with advanced stage of CKM syndrome and focused on examining the prognostic significance of PHDI and the potential mediation effect by inflammatory-nutritional indices. Method A total of 4,578 advanced (stage 3 and 4) CKM participants were included in NHANES. The PHDI was calculated using 24-h dietary assessments and included 14 food groups, with a possible range from 0 to 140 points. The primary outcome was all-cause mortality and the secondary outcome was cardiovascular disease (CVD) mortality. Kaplan-Meier curves, Cox proportional hazards models, and restricted cubic splines were used to study the association between PHDI and mortality risk. Mediation analysis was used to explore the mediation role of Prognostic Nutritional Index (PNI). Result For a median follow-up of 10.8 years, 1,716 deaths (37.5%) were reported. In the adjusted multivariable model, compared with the lowest quintile, participants in the highest quintile of PHDI had lower risk of all-cause mortality (hazard ratio[HR], 0.78; 95% CI, 0.68-0.89), CVD mortality (HR, 0.73; 95% CI, 0.58-0.92). Each 10-point increase in PHDI was independently associated with reduced risk of mortality significantly, with all-cause mortality showed HR of 0.93 (95% CI: 0.89–0.97) and CVD mortality showed HR of 0.92 (95% CI: 0.89–0.99) (both P < 0.05) .However, no significant association between PHDI and CVD mortality risk was found when accounting for non-CVD mortality in the competing-risk model (P>0.05). Mediation analyses showed that the PNI explained 12.09% (95% CI 5.34–30.19%) of the effect of PHDI on all-cause mortality. Conclusion The PHDI, a healthy diet recommended by the EAT-Lancet Commission, was independently associated with lower all-cause mortality among people with advanced CKM syndrome, partially mediated by inflammatory–nutrition indexes. The planetary health diet was therefore a recommended diet for improving the prognosis of patients with advanced CKM syndrome.