Comparability of a short food frequency questionnaire to assess diet quality: the DISCOVER study

Relative validity of a non-quantitative 33-item dietary screener with a semi-quantitative food frequency questionnaire among young adults

The objective of the study was to assess the concordance and ranking ability of a non-quantitative 33-item dietary screener developed to assess the diet of young adults in Norway, 'MyFoodMonth 1.1', compared to a semi-quantitative food frequency questionnaire (FFQ). Data were collected in a cross-sectional dietary survey evaluating the diets of students at the University of Agder, in southern Norway. The students were asked to complete both a dietary screener and an FFQ. Data collection was carried out from September to December 2020. Participants were first-year university students aged ≥18 years familiar with Scandinavian language. Almost half of the eligible sample (n 344) was excluded due to not completing the FFQ, compared to 1⋅7 % not completing the dietary screener, resulting in 172 (66 % female) participants with a median age of 21 years. For most items of the dietary screener (n 27/33, 82 %), all aspects of diet quality and components of the Diet Quality Score showed moderate-to-strong concordance with the FFQ evaluated using Kendall's tau-b analyses (t > 0⋅31), supported by visual inspection of box and whisker plots and descriptive ranking ability in a cross-tabulation. There was little evidence to suggest that concordance was dependent on sex. The concordance and ranking ability of 'MyFoodMonth 1.1' is considered satisfactory compared to a semi-quantitative FFQ. This rapid dietary assessment instrument presents a valuable addition to traditional instruments and a possible solution to recruit hard-to-reach parts of the population.

Development and Comparability of a Short Food-Frequency Questionnaire to Assess Diet in Prostate Cancer Patients: The Role of Androgen Deprivation Therapy in CArdiovascular Disease - A Longitudinal Prostate Cancer Study (RADICAL PC) Substudy

BACKGROUND

There are few concise tools to evaluate dietary habits in men with prostate cancer in Canada.

OBJECTIVE

The aim was to develop a short food-frequency questionnaire (SFFQ) in a cohort of prostate cancer patients.

METHODS

A total of 130 men with prostate cancer completed the SFFQ and a validated comprehensive food-frequency questionnaire (CFFQ). Both questionnaires were administered at baseline and 6 mo later.

RESULTS

We found good correlation between the SFFQ and the CFFQ for seafood, dairy, egg, fruits, potatoes, grains, soft drinks, and processed meat (Spearman rank correlation >0.5). Moderate correlation was found for meat, sweets, vegetables, protein, and carbohydrates (Spearman rank correlation: 0.3-0.5). We found a weaker correlation for total fat measured by SFFQ and CFFQ (Spearman rank correlation <0.3). There was adequate reproducibility during the 6-mo follow-up among all food groups and nutrients, with the exception of meat.

CONCLUSIONS

Our SFFQ can be considered an appropriate tool to be used for measuring the habitual dietary intake of prostate cancer patients. This trial was registered at www.clinicaltrials.gov as NCT03127631.

Can a Simple Dietary Index Derived from a Sub-Set of Questionnaire Items Assess Diet Quality in a Sample of Australian Adults?

Large, longitudinal surveys often lack consistent dietary data, limiting the use of existing tools and methods that are available to measure diet quality. This study describes a method that was used to develop a simple index for ranking individuals according to their diet quality in a longitudinal study. The RESIDential Environments (RESIDE) project (2004-2011) collected dietary data in varying detail, across four time points. The most detailed dietary data were collected using a 24-item questionnaire at the final time point (n = 555; age ≥ 25 years). At preceding time points, sub-sets of the 24 items were collected. A RESIDE dietary guideline index (RDGI) that was based on the 24-items was developed to assess diet quality in relation to the Australian Dietary Guidelines. The RDGI scores were regressed on the longitudinal sub-sets of six and nine questionnaire items at T4, from which two simple index scores (S-RDGI1 and S-RDGI2) were predicted. The S-RDGI1 and S-RDGI2 showed reasonable agreement with the RDGI (Spearman's rho = 0.78 and 0.84; gross misclassification = 1.8%; correct classification = 64.9% and 69.7%; and, Cohen's weighted kappa = 0.58 and 0.64, respectively). For all of the indices, higher diet quality was associated with being female, undertaking moderate to high amounts of physical activity, not smoking, and self-reported health. The S-RDGI1 and S-RDGI2 explained 62% and 73% of the variation in RDGI scores, demonstrating that a large proportion of the variability in diet quality scores can be captured using a relatively small sub-set of questionnaire items. The methods described in this study can be applied elsewhere, in situations where limited dietary data are available, to generate a sample-specific score for ranking individuals according to diet quality.