Comparative associations of six dietary pattern indices with mortality among U.S. adults with sarcopenia: a nationally representative cohort study

Dietary patterns may influence survival among individuals with sarcopenia, but evidence comparing different dietary indices remains limited. This study examined the associations of six commonly used dietary pattern indices with all-cause and cardiovascular disease mortality among U.S. adults with sarcopenia. This nationally representative cohort study included 1,774 adults with sarcopenia from the National Health and Nutrition Examination Survey with linked mortality data. Sarcopenia was defined according to the Foundation for the National Institutes of Health criteria using DXA-derived appendicular skeletal muscle mass adjusted for body mass index. Dietary patterns were assessed using the alternate Mediterranean diet score (aMED), Healthy Eating Index-2020 (HEI-2020), Dietary Approaches to Stop Hypertension score (DASH), Planetary Health Diet Index (PHDI), Dietary Inflammatory Index (DII), and Ketogenic Diet Ratio (KDR). Survey-weighted Cox proportional hazards models were used to estimate associations with mortality. Restricted cubic spline analyses were performed to assess dose–response patterns. False discovery rate correction and multiple sensitivity analyses were conducted to evaluate robustness. Among 1,774 adults with sarcopenia, 545 all-cause deaths and 183 cardiovascular deaths occurred during follow-up. In fully adjusted survey-weighted Cox models, compared with the lowest quartile, higher aMED adherence was associated with lower all-cause mortality in Q3 (HR = 0.57, 95% CI: 0.37–0.87) and Q4 (HR = 0.60, 95% CI: 0.39–0.92). Similar but less robust inverse associations were observed for PHDI in Q3 (HR = 0.71, 95% CI: 0.54–0.93) and Q4 (HR = 0.70, 95% CI: 0.54–0.89), whereas the highest DASH quartile showed a weaker inverse association (HR = 0.68, 95% CI: 0.47–0.97). HEI-2020, DII, and KDR did not show robust associations with all-cause mortality. Restricted cubic spline analyses suggested a nonlinear association for aMED and an overall association for DASH, whereas the spline-based overall association for PHDI was not statistically significant. After FDR correction based on spline overall tests, the associations for aMED and DASH remained statistically significant, whereas the PHDI finding was attenuated. No consistent associations with cardiovascular mortality were observed. In U.S. adults with sarcopenia, aMED showed the most consistent inverse association with all-cause mortality, with evidence suggesting a nonlinear dose–response pattern. DASH showed weaker supportive evidence based on spline analyses, whereas PHDI should be interpreted as exploratory after accounting for spline-based multiple testing. These findings support the potential relevance of dietary pattern quality, particularly Mediterranean-style adherence, in sarcopenia, while cause-specific mortality findings require cautious interpretation.