Development and Evaluation of a Dietary Approaches to Stop Hypertension Dietary Index with Calorie-Based Standards in Equivalent Units: A Cross-Sectional Study with 24-Hour Dietary Recalls from Adult Participants in the National Health and Nutrition Examination Survey 2007-2010.

BACKGROUND: Dietary indexes to assess accordance with the Dietary Approaches to Stop Hypertension (DASH) dietary pattern are useful tools in studies with health-related outcomes. However, scoring algorithms of the dietary index can affect the range of its applications.

OBJECTIVE: The purposes of this study were to develop a DASH dietary index with calorie-based standards in equivalent units and to evaluate the validity and reliability of the index.

METHODS: Calorie-based standards for nine components were determined based on recommended intakes in the DASH eating plan and dietary intakes estimated from two 24-hour dietary recalls of adult participants in the National Health and Nutrition Examination Survey 2007-2008, 2009-2010 (n=9,720). Evaluation tests included descriptive analyses of index scores among US adults stratified by sex and smoking status. Spearman's rank correlations were used to examine the relationships among components and total scores. The developed index was compared with two DASH dietary indexes that use different scoring algorithms to examine the association between total scores and blood pressure status through multivariable regression models.

RESULTS: The newly developed index consisted of seven food group and two nutrient components. The mean and median of total scores among US adults were 42.3 (95% CI 41.6 to 43.0) and 41.6 of 90 points, respectively. The mean total scores among adult women and non-current smokers were higher than their counterparts (P<0.001). The absolute correlation coefficients among the components and between each component and the sum of other components were ≤0.33 and ≤0.35, respectively. After adjusting for age and race/ethnicity, an association between total scores and blood pressure status was found in adult women (P<0.001), but not in adult men. The same pattern was found when the two indexes were used, but the strength of the association varied across the three indexes.

CONCLUSIONS: The developed index appeared to measure accordance with the DASH dietary pattern based on the dietary data from US adults. Further studies are warranted for various applications of the index.