Tool Library Tool Information
Validation Information: Quantitative FFQ (QFFQ)
A culture-sensitive quantitative food frequency questionnaire used in an African population: 2. Relative validation by 7-day weighed records and biomarkers
Objective: To determine the relative validity of the culture-sensitive quantitative food frequency questionnaire (QFFQ) developed for the Transition, Health and Urbanisation in South Africa (THUSA) study by 7-day weighed food records, urinary nitrogen excretion and basal metabolic rate (BMR).
Design: A cross-sectional study.
Setting: A community-based study in a population stratified according to level of urbanization.
Subjects: Residents of the North West Province, South Africa, aged between 15 and 65 years. The weighed food record study comprised 74 participants while 104 participants collected 24-hour urine samples.
Methods: All participants were interviewed using the QFFQ. For the weighed food record study, participants kept detailed weighed food diaries for seven consecutive days. For the urinary nitrogen study, participants made one 24-hour urine collection. Completeness of the urine collections was checked against 240mg para-aminobenzoic acid. BMR was estimated by the Schofield equations.
Results: Spearman rank correlation coefficients between the QFFQ and weighed food record ranged between 0.14 (fibre) and 0.59 (vitamin C). The QFFQ tended to underestimate intakes compared with the weighed records. Quintile distributions were similar for both methods. The correlation between urinary nitrogen excretion and dietary intake was poor. Possible underreporting was identified for 43% of the participants with the QFFQ and 28% with the weighed food record.
Conclusions: The QFFQ appeared to be a relatively valid instrument for the assessment of dietary intakes of the population of the North West Province. The use of biomarkers in this population was difficult and needs further investigation.
Total number of nutrients validated: 8
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: 4
- Micronutrients: 4
|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||Adolescents, Adults||Both||Energy (kcal)||68||805.1||0.31 (S)||N/C||32||5||-1495||1632|
|Energy (kJ)||285||3368.4||0.31 (S)||N/C||32||5||-6257||6827|
|Protein (g)||9.8||28.7||0.30 (S)||N/C||31||5|
|Fat (g)||3.2||33.7||0.25 (S)||N/C||36||5|
|Carbohydrate (g)||-3.2||121.3||0.31 (S)||N/C||34||5|
|Fibre (g)||1.1||10.4||0.14 (S)||N/C||30||5|
|Calcium (mg)||51.9||287.3||0.24 (S)||N/C||43||5|
|Iron (mg)||0.5||4.6||0.20 (S)||N/C||28||5|
|Vitamin C (mg)||-12.5||70.2||0.60 (S)||N/C||66||5|
|Biomarkers||Adolescents, Adults||Both||Protein (g)||10||38.8||0.01(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.
MacIntyre U, Venter C, Vorster H. A culture-sensitive quantitative food frequency questionnaire used in an African population: 2. Relative validation by 7-day weighed records and biomarkers. Public health nutrition. 2001;4(1):63-71.