Using SAS to Expand the Application of Standard Measures and Guide Statistical Explorations: Creating Healthy Eating Index Scores Using Nutrition Data System for Research Output

New measures, summarizing several variables related to a common health construct are frequently developed in the healthcare industry to provide more valid or complete descriptions of quality and health concepts. We created a SAS® program to calculate a measure of diet quality, the Healthy Eating Index (HEI, http://www.cnpp.usda.gov/HealthyEatingIndex.htm) using output from a widely applied dietary software package, Nutrition Data System for Research (NDSR, http://www.ncc.umn.edu/products/ndsr.html). Currently, application of the HEI in research and clinical assessment is limited by the challenges posed in calculating the HEI using the highly complex and detailed NDSR output. The SAS program extracts the required NDSR output files and then calculates the combination of algebraic manipulations and logical statements to obtain HEI scores. We also offer suggestions for increasing usability such as with the %INCLUDE statement and show how the program can be used to explore related statistical issues such as reliability via PROC MIXED.