Diet Quality Index for older adults (DQI-65): development and use in predicting adherence to dietary recommendations and health markers in the UK National Diet and Nutrition Survey

Diet quality indexes (DQIs) are useful tools for assessing diet quality in relation to health and guiding delivery of personalised nutritional advice, however existing DQIs are limited in their applicability to older adults (aged ≥65 years). Therefore, this research aimed to develop a novel evidence-based DQI specific to older adults (DQI-65). Three DQI-65 variations were developed to assess the impacts of different component quantitation methods and inclusion of physical activity. The variations were: Nutrient and Food-based DQI-65 (NFDQI-65), NFDQI-65 with Physical Activity (NFDQI-65+PA) and Food-based DQI-65 with Physical Activity (FDQI-65+PA). To assess their individual efficacy, the NFDQI-65, NFDQI-65+PA and FDQI-65+PA were explored alongside the validated Healthy Eating Index-2015 (HEI-2015) and Alternative Healthy Eating Index-2010 (AHEI-2010) using data from the cross-sectional UK National Diet and Nutrition Survey (NDNS) rolling programme. Scores for DQI-65 variations, the HEI-2015 and AHEI-2010 were calculated for adults ≥65 years from years 2-6 of the NDNS (n=871). Associations with nutrient intake, nutrient status and health markers were analysed using linear and logistic regression. Higher DQI-65s and HEI-2015 scores were associated with increased odds of meeting almost all of our previously proposed age-specific nutritional recommendations, and with health markers of importance for older adults, including lower body mass index, lower medication use and lower C-reactive protein (P<0.01). Few associations were observed for the AHEI-2010. This analysis suggests value of all three DQI-65s as measures of dietary quality in UK older adults. However, methodological limitations mean further investigations are required to assess validity and reliability of the DQI-65s.