Household food purchases are potential indicators of the quality of the home food environment, and grocery purchase behavior is a main focus of US Department of Agriculture (USDA) nutrition education programs; therefore, objective measures of grocery purchases are needed.
The objective of the study was to evaluate the Grocery Purchase Quality Index-2016 (GPQI-2016) as a tool for assessing grocery food purchase quality by using the Healthy Eating Index-2015 (HEI-2015) as the reference standard.
In 2012, the USDA Economic Research Service conducted the National Household Food Acquisition and Purchase Survey. Members of participating households recorded all foods acquired for a week. Foods purchased at stores were mapped to the 29 food categories used in USDA Food Plans, expenditure shares were estimated, and GPQI-2016 scores were calculated. USDA food codes, provided in the survey database, were used to calculate the HEI-2015.
All households in the 48 coterminous states were eligible for the survey. The analytic sample size was 4,276 households.
GPQI-2016 and HEI-2015 scores were compared.
Correlation of scores was assessed using Spearman's correlation coefficient. Linear regression models with fixed effects were used to determine differences among various subgroups of households.
The correlation coefficient for the total GPQI-2016 score and the total HEI-2015 score was 0.70. For the component scores, the strongest correlations were for Total and Whole Fruit (0.89 to 0.90); the weakest were for Dairy (0.67), Refined Grains (0.66), and Sweets and Sodas/Added Sugars (0.65) (all, P<0.01). Both the GPQI-2016 and HEI-2015 were significantly different among subgroups in expected directions.
Overall, the GPQI-2016, estimated from a national survey of households, performed similarly to the HEI-2015. The tool has potential for evaluating nutrition education programs and retail-oriented interventions when the nutrient content and gram weights of foods purchased are not available.