Health Stream Literature Summary

Health Stream Literature Summary - Issue 58 - June 2010

Relative validity of a self-completion 24 h recall questionnaire to assess beverage consumption among schoolchildren aged 7 to 9 years
Muckelbauer, R., Libuda, L. and Kersting, M. (2010) Public Health Nutrition, 13(2); 187-195.

The drinking habits of children influence their total diet quality and possibly childhood obesity, which is related to the consumption of sugar-containing beverages. The accurate assessment of dietary intake in children is difficult, and for large-scale trials the data collection methods must be relatively quick, cost-effective, easy to implement and appropriate for the age group targeted. A self-completion semi-quantitative questionnaire was developed for a large-scale intervention trial focusing on the prevention of overweight by promoting water consumption. This questionnaire was based on the concept of a 24 h recall to assess changes in the beverage consumption of elementary-school children in the classroom setting. This current study was conducted to test the validity of this 24 h recall questionnaire (RQ) in children aged 7 to 9 years using a parent-completed 24 h weighed diet record (WR) as the reference method.

A subsample of participants aged 7 to 9 years were enrolled in this validation study from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study cohort during their visit for the annual assessment. The DONALD Study collects information on the nutrition, development, metabolism and health status of subjects between infancy and early adulthood.

The RQ asked for the number of glasses of seven beverage categories consumed at five time intervals over the previous 24 h. The time intervals were named: (i) this morning for breakfast at home; (ii) this morning at school; (iii) yesterday at supper and afterwards; (iv) yesterday between lunch and supper; and (v) yesterday at lunchtime. Children could choose between full glasses, half-full glasses and an empty glass. The beverage categories included: (i) tap water; (ii) tea; (iii) mineral water; (iv) milk (including milk drinks); (v) soft drinks; (vi) juices (fruit and vegetable juices, fruit drinks, juice mixed with sparkling water); and (vii) other beverages (e.g. coffee, drinking the child could not categorise). Illustrations were provided to help identification of the appropriate category.

The DONALD Study includes 3 day weighed dietary records conducted on three consecutive days. The participants' parents weigh and record foods and fluids consumed during this period, as well as leftovers, using electronic food scales to the nearest 1g. Children were required to complete the RQ on the second or third day of the annual 3 day parent-completed weighed record (WR), just before lunchtime and preferably not on the weekend. The main outcomes of the present validation study for measuring the agreement between the RQ and the WR as the reference method were: (i) the ability for the RQ to classify individuals into consumers and non-consumers by beverage category; (ii) the ability of the RQ to estimate the exact beverage volume; and (iii) the ability of the RQ to rank individuals according to beverage volume.

There were 35 participants from the DONALD study who completed the RQ. The majority of children were correctly classified as consumers or non-consumers by the RQ with match rates ranging from 91% to 97%. Kappa coefficients (k) were calculated and values between 0.78 and 0.94 were obtained which represent good to very good agreement between the RQ and WR. The median total 24 h beverage volume was higher in the RQ than in the WR (P = 0.015). The reported volume of each of the single beverage categories did not differ between the RQ and WR. Spearman rank correlation coefficients between the RQ and WR ranged from r = 0.86 to r = 0.91 for the single beverage categories, whereas correlation was worse for the total 24 h beverage volume, r = 0.72. The RQ on average overestimated total 24 h beverage volume by 114 ml. Agreement in ranking into tertiles by total beverage volume was fair as indicated by k = 0.23, and 49% of the participants were classified into the correct tertiles by the RQ. The individual beverage categories agreement was moderate to good for juice/soft drinks (k = 0.44), for milk (k = 0.57) and water (k = 0.70). A small percentage of participants (0-3%) were grossly misclassified into the opposite tertile for the total 24 h consumption and for the different beverage categories. Differentiation between tap water and mineral water was examined and tap water was not misclassified at all and mineral water was misclassified as tap water in one of fifty-one cases. Differentiation between juices and soft drinks showed soft drinks were misclassified as juices in 13% of all cases and juices as soft drinks in 5% of all cases.

This study indicated that children had good recall of the beverage categories consumed. The RQ also provided valid estimations of the volume consumed in the single beverage categories but estimation of the total 24 h beverage volume was not satisfactory. This self-completed questionnaire was found to be applicable even in young children of elementary-school age as it had illustrations in the design which assumed low reading and writing skills. The RQ was well suited for assessing beverage consumption among large samples of children due to its self-completion design. The validity of the RQ was assessed on an individual level at home under supervision of parents instead of teachers and parental support in the completion of the questionnaire cannot be excluded completely even though parents were asked not to do so. Further large-scale validation studies are required in the school setting to determine whether the RQ can serve as a practical tool for the evaluation of children's drinking habits.

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