Reliability and relative validity of a diet index score for adults derived from a self‐reported short food survey. Issue 3 (14th September 2016)

• Record Type: Journal Article
• Authors: Hendrie, Gilly A.; Rebuli, Megan A.; Golley, Rebecca K.
• Is Part Of: Nutrition & dietetics. Volume 74:Issue 3(2017)
• Page Start: 291
• Page End: 297
• Publication Date: 2016-09-14
• Subjects: diet questionnaire -- dietary assessment -- reliability -- short food survey -- validity; Nutrition -- Periodicals; Dietetics -- Periodicals; 613.205
• DOI: 10.1111/1747-0080.12303
• Languages: English
• ISSNs: 1446-6368

Abstract

Abstract : Aim: Assess the reliability and relative validity of a diet index score for adults derived using a 38‐item online survey. Methods: The short food survey (SFS) measured 'usual' intake of seven food groups, three food choice indicators and variety; and was completed by 61 adults aged 19‐50 years from Adelaide, Australia. A score was applied to assess compliance with the 2013 Australian Dietary Guidelines. Reliability of the survey was measured between two administrations one week apart; and validity by comparing the first administration to the average of three 24‐hour dietary recalls. Statistical analyses included paired samples t ‐tests, intra‐class correlation coefficient (ICC), percentage agreement, Cohen's kappa coefficients and Bland‐Altman plots. Results: Estimates of daily food group servings were reliable (within 0.3 servings, P > 0.05) but not valid for all foods groups. The mean total index score was approximately 70 points (out of 100) on both SFS administrations (ICC = 0.71 (95% CI 0.56:0.81). Relative validity analysis showed moderate correlation between SFS#1 and 24‐hour recalls (ICC = 0.43 (0.21:0.62, P < 0.001)), with 51% agreement in allocation to tertiles of diet quality between methods (k = 0.262, P = 0.004). The survey overestimated the diet index score by an average of 12.7 points out of 100 [‐20.11:42.94] in comparison to recalls. Conclusions: The survey overestimated compliance with guidelines relative to dietary recalls. It demonstrated good reliability; however, the validity of estimating intake of some food groups needs improvement. Future refinement will provide a valuable online tool to assess compliance with the Australian dietary recommendations.