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Validation Information: Scottish Collaborative Group FFQ
Repeatability and validity of a food frequency questionnaire in free-living older people in relation to cognitive function
Objectives: To determine the repeatability and validity of a self-administered, 175-item food frequency questionnaire (FFQ) in free-living older people and to assess whether these are influenced by cognitive function.
Participants and Setting: 189 free-living people aged 64-80y were recruited from participants in a previous study.
Design: To assess repeatability, 102 (52M, 50F) participants completed the FFQ on two occasions three months apart. To assess validity, another 87 participants (44M, 43F) completed the FFQ and a four-day weighed diet record three months later. 25 nutrients were studied.
Results: For repeatability, Spearman rank correlation coefficients were above 0.35 (p<0.05) for all nutrients. Cohen's weighted Kappa was above 0.4 for all nutrients except starch, riboflavin, retinol, β-carotene, and calcium. There were no substantial differences in correlation coefficients between sub-groups divided by short-term memory test score. There was no clear pattern for correlation coefficients in sub-groups divided by executive function test score. For validity, the Spearman rank correlation coefficients were above 0.2 (p<0.05) for all nutrients except fat, mono-unsaturated fatty acids, niacin equivalents and vitamin D, and Cohen's weighted kappa was above 0.4 for alcohol and was above 0.2 for 13 other nutrients. Participants in the lowest-score groups of short-term memory and executive function had the lowest median Spearman correlation coefficient.
Conclusions: The FFQ had reasonable repeatability and validity in ranking nutrient intakes in this population though the results varied between nutrients. Poor short-term memory or executive function may affect FFQ validity in ranking nutrient intakes.
Total number of nutrients validated: 25
Not all of the nutrients validated in the validation studies are included in the table below, as statistical data was only selected to be displayed for a number of nutrients, this included:
- Saturated Fat
- Mono-unsaturated Fat
- Poly-unsaturated Fat
- Non‐starch polysaccharides(NSP)
- Folic Acid
- Vitamin B12
- Vitamin C
- Fruit & Vegetables
- Urinary Nitrogen
To find information on the other validated nutrients please read the validation study.
- Macronutrients: 9
- Micronutrients: 15
|Comparator||Lifestage||Sex||Nutrient Measured||Mean Difference||Standard Deviation||Correlation Coefficient||Cohen's Kappa Coefficient||Percentage Agreement||Percentage Agreement Categories||Lower Limits of Agreement||Upper Limits of Agreement|
|Weighed Food Diary||Elderly||Male Only||Energy (kcal)||-75|
|Protein (g)||-10||0.34 (S)|
|Fat (g)||-45||0.29 (S)|
|Saturated Fat (g)||1||0.29 (S)|
|MUFA (g)||2||0.13 (S)|
|PUFA (g)||2||0.19 (S)|
|Total Sugars (g)||13||0.24 (S)|
|Calcium (mg)||129||0.58 (S)|
|Iron (mg)||-1.3||0.46 (S)|
|Zinc (mg)||-0.3||0.08 (S)|
|Retinol (µg)||96||0.23 (S)|
|Folate (µg)||6||0.51 (S)|
|Vitamin C (mg)||16||0.58 (S)|
|Weighed Food Diary||Elderly||Female Only||Energy (kcal)||380|
|Protein (g)||13||0.26 (S)|
|Fat (g)||9||0.16 (S)|
|Saturated Fat (g)||9||0.50 (S)|
|MUFA (g)||4||0.26 (S)|
|PUFA (g)||4||0.31 (S)|
|Total Sugars (g)||34||0.36 (S)|
|Calcium (mg)||345||0.38 (S)|
|Iron (mg)||2.6||0.36 (S)|
|Zinc (mg)||1.9||0.47 (S)|
|Retinol (µg)||327||0.29 (S)|
|Folate (µg)||93||0.24 (S)|
|Vitamin C (mg)||37.7||0.38 (S)|
|Weighed Food Diary||Elderly||Both||Protein (g)||0.30 (S)||0.26||40||4|
|Fat (g)||0.20 (S)||0.15||30||4|
|Saturated Fat (g)||0.35 (S)||0.21||30||4|
|MUFA (g)||0.17 (S)||0.11||26||4|
|PUFA (g)||0.25 (S)||0.19||35||4|
|Total Sugars (g)||0.33 (S)||0.19||32||4|
|Calcium (mg)||0.48 (S)||0.24||32||4|
|Iron (mg)||0.41 (S)||0.32||43||4|
|Zinc (mg)||0.22 (S)||0.09||26||4|
|Retinol (µg)||0.26 (S)||0.17||29||4|
|Folate (µg)||0.40 (S)||0.26||41||4|
|Vitamin C (mg)||0.52 (S)||0.32||39||4|
Some results have been calculated using statistical techniques based on the published data.
For further information on statistical terms click on Statistical tests used in validation studies
All correlations coefficients in the table are unadjusted unless stated otherwise. For adjusted correlation coefficients and other statistical methods used in the study e.g. paired t-tests, please read the validation articles.
- # Adjusted
- † Energy adjusted.
- ‡ For loge-transformed, energy-adjusted nutrient intakes.
- ^ Adjacent included.
- ᵟ Participants provided identical responses.
- (w) = Weighted.
Jia X, Craig LC, Aucott LS, Milne AC, McNeill G. Repeatability and validity of a food frequency questionnaire in free-living older people in relation to cognitive function. The journal of nutrition, health & aging. 2008 Dec 1;12(10):735-41.