Tool Library Tool Information
Validation Information: Oxford FFQ
The validity of dietary assessment in general practice
Objective: To validate a range of dietary assessment instruments in general practice.
Methods: Using a randomised block design, brief assessment instruments and more complex conventional dietary assessment tools were compared with an accepted “relative” standard-a seven day weighed dietary record. The standard was checked using biomarkers, and by performing test-retest reliability in additional subjects (n=29).
Outcomes: Agreement with weighed record. Percentage agreement with weighed record, rank correlation from scatter plot, rank correlation from Bland-Altman plot. Reliability of the weighed record.
Setting: Practice nurse treatment room in a single suburban general practice.
Subjects: Patients with risk factors for cardiovascular disease (n=61) or age/sex stratified general population group (n=50).
Results: Brief self completion dietary assessment tools based on food groups eaten during a week show reasonable agreement with the relative standard. For % energy from fat and saturated fat, nonstarch polysaccharide, grams of fruit and vegetables and starchy foods consumed the range of agreement with the standard was: median % difference -6% to 12%, rank correlation 0.5 to 0.6. This agreement is of a similar order to the reliability of the weighed record, as good as or better than test standard agreement for more time consuming instruments, and compares favourably with research instruments validated in other settings. Underreporting of energy intake was common (40%) and more likely if subjects were obese (body mass idex (BMI) ≥30 60% under-reported; BMI <30 29%, p<0.001).
Conclusion: Under-reporting of absolute energy intake is common, particularly among obese patients. Simple self assessment tools based on food groups, designed for practice nurse dietary assessment, show acceptable agreement with a standard, and suggest such tools are sufficiently accurate for clinical work, research, and possibly population dietary monitoring.
Total number of nutrients validated: 2
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: 1
- Micronutrients: 1
|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||Adults, Elderly||Both||Fibre (NSP) (g)||26% (Median)||0.38 (S)|
|Vitamin C (mg)||54.6% (Median)||0.56 (S)|
|Fruit and Vegetables (g)||66.4% (Median)||0.59 (S)|
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.
Little P, Barnett J, Margetts B, Kinmonth AL, Gabbay J, Thompson R, Warm D, et al. The validity of dietary assessment in general practice. Journal of Epidemiology and Community Health. 1999 Mar 1;53(3):165-72.