Concurrent and construct validity of Mediterranean diet scores as assessed by an FFQ

Abstract

Objective: The aim of the present study was to assess the concurrent and construct validity of two diet-quality indices, a modified Mediterranean diet score (mMDS) and a Mediterranean-like diet score (MLDS) additionally incorporating unhealthy food choices, as determined by an FFQ. Design: A validation study assessing FFQ intake estimates compared with ten or more unannounced 24 h recalls. Pearson's correlation coefficients, intraclass correlation coefficients (ICC), Bland-Altman plots and the limits of agreement method were used to assess the between-method agreement of scores. Construct validity was shown using associations between nutrient intakes derived from multiple 24 h recalls and the mMDS and MLDS derived from the FFQ. Setting: Gerona, Spain. Subjects: A total of 107 consecutively selected participants from a populationbased cross-sectional survey. Results: Pearson's correlations for the energy-adjusted mMDS and MLDS compared with multiple recalls were 0?48 and 0?62, respectively. The average FFQ energy-adjusted mMDS and MLDS were 102 % and 98 % of the recall-based mMDS and MLDS estimates, respectively. The FFQ under-and overestimated dietary recall estimates of the energy-adjusted MLDS by 28 % and 25 %, respectively, with slightly wider boundaries for the mMDS (31 % and 34 %). The ICC, which assesses absolute agreement, was similar to Pearson's correlations (mMDS 5 0?48 and MLDS 5 0?61). The mean differences between methods were similar across the range of average ratings for both scores, indicating the absence of bias. The FFQderived mMDS and MLDS correlated in the anticipated directions with intakes of eleven (73?3 %) and thirteen of fifteen nutrients (86?7 %), respectively. Conclusions: The FFQ provides valid estimates of diet quality as assessed by the mMDS and MLDS.

The Dutch Healthy Diet index as assessed by 24 h recalls and FFQ: associations with biomarkers from a cross-sectional study

“…The correlation between the DHD-index based on FFQ data and based on 24hR data was comparable with the correlation ( r 0·48) reported by Benítez-Arciniega et al ( 30 ) , who compared the ‘Modified Mediterranean diet score’ based on FFQ data with the score based on twelve 24hR. However, our observed correlation was lower than the correlation ( r 0·72) reported by Newby et al.…”

“…Well over a half of the participants in the present study were classified into the same tertile; this result is similar to the results from cross-classifications between a FFQ and 24hR on food groups ( 30 , 31 ) . Furthermore, Kendall's τ-b coefficient showed a moderate agreement between the tertiles of the DHD-index based on FFQ and 24hR data.…”

Mediterranean Diet Score and prostate cancer risk in a Swedish population-based case–control study

“…The validation study of an FFQ almost identical to the one used in the CAPS study showed low to moderate correlation for several food items ( 19 ) ; however, high correlation coefficients between FFQ and food records are rarely achieved ( 58 ) . Another study validating a modified MDS version assessed by an FFQ against 24-h recalls showed a Pearson's correlation coefficient of 0·48, and the average FFQ-based score was 102 % of the recall-based score ( 59 ) . In the present study, the use of energy-adjusted dietary intake reduces the potential influence of bias due to measurement error.…”

Validity of a short diet-quality index to predict changes in anthropometric and cardiovascular risk factors: a simulation study

“…Dietary intake data derived from a validated full-length food frequency questionnaire (FFQ) 10,11 were employed to simulate responses that would have been obtained using the sDQS. The DQI derived from the simulated data was calculated, as described in the validation study.…”