The validity of dietary assessment in general practice

Abstract

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 BlandAltman 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 % diVerence −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. (J Epidemiol Community Health 1999;53:165-172)

Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial

“…The energy intake measured from 7-day dietary records in the present study is possibly underestimated and should make reservation, as subjects tend to eat less or just report less during the period of dietary reporting. 28,29 Additionally, the protein-E% in both groups reverted slightly towards baseline levels during months 6-12, but the difference between the groups was significant throughout most of the trial as confirmed by the difference in 24-h urinary excretion.…”

The impact of behavioral counseling on stage of change in fat intake, physical activity, and cigarette smoking in adults at increased risk of coronary heart disease

“…Dietary fat intake was assessed by the Dietary Instrument for Nutritional Education, a validated food frequency questionnaire. 16,17 Physical activity was measured as number of episodes of activity in the last 4 weeks as defined by the UK National Fitness Survey. 18 …”

The association between diet and chronic obstructive pulmonary disease in subjects selected from general practice

“…fruit, may have been over-reported. However, HEA3 has previously been shown to accurately assess dietary intake of such foods against a 7-day weighed record [18]. Despite any possible over-reporting, there is no reason why cases should report diet differently to controls and subjects who had a diagnosis likely to be associated with dietary change, such as ischaemic heart disease or diabetes, were excluded.…”

“…After exclusions, the remaining subjects were mailed the HEA3 dietary food frequency questionnaire, validated for use in general practice [18]. This questionnaire asks the frequency (day, week or month) and portion size (small, medium, large) of intake of foods belonging to the six main food groups: fruit and vegetables (including juice), meats and proteins, dairy produce, starchy foods, snack items and fats.…”