Diet quality and all-cause mortality among U.S. adults, estimated from NHANES, 2003-2008.

OBJECTIVE We assessed the ability of the Prime Diet Quality Score (PDQS) to predict mortality in a United States (U.S.) population and compared its predictiveness with that of the Healthy Eating Index-2015 (HEI-2015). DESIGN PDQS and HEI-2015 scores were derived using two 24-hour recalls and converted to quintiles. Mortality data were obtained from the 2015 Public-Use Linked Mortality File. Associations between diet quality and all-cause mortality were evaluated using multivariable Cox proportional hazards models, and predictive performance of the two metrics were compared using a Wald test of equality of coefficients with both scores in a single model. Finally, we evaluated associations between individual metric components and mortality. SETTING A prospective analysis of the U.S. National Health and Nutrition Examination Survey (NHANES) data. PARTICIPANTS 5,525 participants from three survey cycles (2003-2008) in the NHANES aged 40 years and over. RESULTS Over the 51,248 person-years of follow-up (mean: 9.2 years), 767 deaths were recorded. In multivariable models, hazard ratios between the highest and lowest quintiles of diet quality scores were 0.70 (95%CI: 0.51, 0.96, p-trend=0.03) for the PDQS, and 0.77 (95%CI: 0.57, 1.03, p-trend=0.20) for the HEI-2015. The PDQS and HEI-2015 were similarly good predictors of total mortality (p-difference=0.88). CONCLUSION Among U.S. adults, better diet quality measured by the PDQS was associated with reduced risk of all-cause mortality. Given that the PDQS is simpler to calculate than the HEI-2015, it should be evaluated further for use as a diet quality metric globally.