Assessing dietary intakes in food environment research: Implications for policy and practice

1. SHARON KIRKPATRICK University of WaterlooJILL REEDY, KEVIN DODD, AMY SUBAR, FRAN THOMPSON, ROBIN MCKINNONUS National Cancer Institute EBONEÉ BUTLER University of North Carolina at Chapel Hill Assessing dietary intakes in food environment research: Implications for policy and practice

2. The food environment, diet and health

3. The food environment, diet and health Lytle L, AJPM 2009

4. Recent reviews highlight a lack of consensus in the existing literature

5. What might account for inconsistencies in the evidence? • Context • Measures of the food environment: • Capturing different aspects, e.g., density or distance to a particular type of food outlet, variety and quality of in-store offerings, perceived availability of food in a particular area • Error • Measures of dietary intake: • Capturing different aspects, e.g., whole diet versus particular foods or food groups • Error

6. What might account for inconsistencies in the evidence? • Context • Measures of the food environment: • Capturing different aspects, e.g., density or distance to a particular type of food outlet, variety and quality of in-store offerings, perceived availability of food in a particular area • Error • Measures of dietary intake: • Capturing different aspects, e.g., whole diet versus particular aspects of diet • Error

7. Measuring dietary outcomes in food environment research • Widely recognized that data collected using self-report dietary instruments contain substantial bias • Bias can: • Mask relationships that actually exist • Result in spurious effects • Particularly problematic if differential error among populations (e.g., low versus high income) • Reduce statistical power Barrier to policy and program interventions

8. Methods for assessing diet Bias less more Number of dietary factors more less Distribution of dietary factors more less more Time less [Money] more less Food frequency questionnaire Brief instrument (screener) Recall or record

9. Methods for assessing diet • 24 hour recalls and food records • Food frequency questionnaires

10. Methods for assessing diet • Brief instruments focused on ‘indicator foods’ (e.g., fruits, vegetables, salty or sugary snacks) • Screeners or checklists • 1 or 2 questions (e.g., how many servings of fruit/vegetables do you usually eat each day?)

11. Research question and method • What is the state of food environment research in terms of assessment of dietary outcomes? • Review of peer-reviewed literature published from January 2007 through June 2012 • Food environments include food stores, restaurants, schools, home, farmers’ markets, recreational facilities, etc. Kirkpatrick et al., AJPM, 2014

12. Search strategy • Systematic search • Search engines: • PubMed, SCOPUS, PsycInfo, Web of Science • Search terms: • [Food or nutrition or diet] AND [environment or community or neighborhood or neighbourhood] AND [measure] AND [assess] • Food environment • Measures of the Food Environment web compilation (appliedresearch.cancer.gov/mfe) • Literature cited by each article

13. 2450 unique articles identified and screened 2082 articles excluded after initial screen 368 abstracts reviewed to assess eligibility 219 articles excluded after review of abstracts 149 full-text articles assessed for eligibility 111 articles excluded after full-text review 38 eligible articles identified 13 additional articles identified via the reference lists of included articles and relevant reviews and the Measures of the Food Environment website 51 articles included in systematic review

14. Dietary assessment in food environment research (n=51)

15. Dietary assessment in food environment research (n=51) Note: - The count of instruments exceeds the number of studies reviewed because one or more studies used multiple instruments. - The outcomes included are those most commonly examined among the studies reviewed. Note that a single study may include multiple outcomes and so the sum of studies examining unique outcomes exceeds the total number of studies reviewed.

16. Dietary assessment in food environment research (n=51) • Tendency toward the use of brief (more error-prone) assessment instruments • Low cost and respondent burden • Results in focus on ‘indicator foods’ (or due to a priori interest in specific food groups?)

17. Dietary assessment in food environment research (n=51) • Existence of bias in dietary data and the potential implications for study results rarely discussed • In several papers, it was noted that the dietary assessment tool was ‘validated’ • Validity often assessed by comparing the instrument to another self-report instrument  limited utility

18. Dietary assessment in food environment research (n=51) • Relationships between food environment features and dietary outcomes more consistent in studies using less error-prone measures

19. Conclusions • Explosion of research examining relationships between features of food environments and dietary intakes • Bias in dietary data may be substantial, particularly if estimates are based on brief dietary instruments • May lead to spurious effects and reduced statistical power to detect associations • Barrier to establishing policy and program interventions to improve diet and health

20. Moving forward • Effects of bias when diet is the outcome (rather than an exposure) not thoroughly examined – need more research to inform strategies • In the meantime? • Start with the best instrument possible: technologic advances allow collection of more detailed and less biased dietary data • Use available strategies to reduce the effects of error (e.g., calibrate data from brief instruments using other sources) • Discuss potential implications of bias on study results and inconsistencies with other studies

21. Questions or comments? sharon.kirkpatrick@uwaterloo.ca