Comparison of Validity of Food Group Intake by FoodFrequency Questionnaire Between Pre- and Postadjustment Estimates Derived from 2-day 24-hour Recalls in Combination with the Probability of Consumption

Validation of a food frequency questionnaire (FFQ) utilising a short-term measurement method ischallenging when the reference method does not accurately reflect the usual food intake. In addition, foodgroup intake that is not consumed on daily basis is more critical when episodically consumed foods arerelated and compared. To overcome these challenges, several statistical approaches have been developedto determine usual food intake distributions. The Multiple Source Method (MSM) can calculate the usualfood intake by combining the frequency questions of an FFQ with the short-term food intake amount data.In this study, we applied the MSM to estimate the usual food group intake and evaluate the validity of anFFQ with a group of 333 Korean children (aged 3-6 y) who completed two 24-hour recalls (24HR) and oneFFQ in 2010. After adjusting the data using the MSM procedure, the true rate of non-consumption for allfood groups was less than 1% except for the beans group. The median Spearman correlation coefficientsagainst FFQ of the mean of 2-d 24HRs data and the MSM-adjusted data were 0.20 (range: 0.11 to 0.40) and0.35 (range: 0.14 to 0.60), respectively. The weighted kappa values against FFQ ranged from 0.08 to 0.25 forthe mean of 2-d 24HRs data and from 0.10 to 0.41 for the MSM-adjusted data. For most food groups, theMSM-adjusted data showed relatively stronger correlations against FFQ than raw 2-d 24HRs data, from0.03 (beverages) to 0.34 (mushrooms). The results of this study indicated that the application of the MSM,which was a better estimate of the usual intake, could be worth considering in FFQ validation studies amongKorean children.