Response rates with different distribution methods and reward, and reproducibility of a quantitative food frequency questionnaire

Abstract

Objectives: To evaluate the use of a self-administered quantitative food frequency questionnaire (QFFQ) in a national dietary survey concerning (a) response rates with different distribution methods and reward; (b) degree of underreporting of energy intake; (c) reproducibility of the QFFQ; and (d) seasonal variation on reported intake. Design and subjects: A pilot study was performed in 1992 to test response rates to the QFFQ with three different distribution methods, with and without reward, in a random sample of 1200 adults aged 16±79 y. In another study, the QFFQ was distributed to a nation-wide, representative random sample of 5008 adults aged 16±79 y during June, September, November 1993 and March 1994. Reproducibility was evaluated among 90 responders to the survey who answered another QFFQ six weeks later. Results: The distribution method combining postal distribution and collecting the QFFQ by interviewer as well as an offer to participate in a lottery, gave the highest response rate (72%). The possibility to get a reward increased the response rate by 9, 14 and 57%, respectively, depending on the distribution method used. The mean daily energy intake and the percentage of subjects claiming to have unlikely low energy intake did not differ signi®cantly between the different ways of distribution. In the main survey the mean ratio between energy intake and estimated basal metabolic rate was 1.58 among men and 1.47 among women, and 37% of men and 45% of women had a ratio below 1.35. Spearman rank correlations between the two QFFQ ranged from 0.48 (edible fats) to 0.91 (coffee) with a median coef®cient of 0.70. For nutrients correlations ranged from 0.55 (carbohydrate E%) to 0.81 (alcohol), with a median coef®cient of 0.72. The season of questionnaire administration was of minor importance for the reported intake of the main foods and nutrients. Conclusions: The QFFQ-method is suitable for use in a Norwegian nutritional surveillance system.

Validity and reproducibility of the NORBAGREEN food frequency questionnaire

“…The FFQ was administered both in spring and in autumn. The observed Spearman's correlation coefficients of 0.51-0.75 in the Finnish study (Table 6) and 0.51-0.83 in the Lithuanian study (Table 7) are comparable to those described for other FFQs (Elmstahl et al, 1996;Bohlscheid-Thomas et al, 1997;Johansson et al, 1997;Ocke et al, 1997;Hu et al, 1999;Persson and Becker, 2002). Seasonal variation might affect the consumption of vegetables, fruit and berries.…”

Children and adolescents with type 1 diabetes eat a more atherosclerosis-prone diet than healthy control subjects

“…In Norway intake of citrus fruits and dietary cholesterol has been shown to vary according to the season among adults [45]. November and March had the highest intake of citrus fruits, while cholesterol was highest in June [45]. This variation would not change the outcome of our results.…”

“…The diabetic subjects recorded their diet during the winterspring season and the control subjects during the autumnwinter season. In Norway intake of citrus fruits and dietary cholesterol has been shown to vary according to the season among adults [45]. November and March had the highest intake of citrus fruits, while cholesterol was highest in June [45].…”

Dietary habits among patients with atopic dermatitis

“…The median body mass index (BMI) for male patients was 23.2 (kgam 2 ) (range 17.4 ± 44.3 (kgam 2 ), and for females 21.6 (kgam 2 ) (range 17.2 ± 30.0 (kgam 2 )). The dietary data for the patients were compared with results from a nationwide dietary survey performed in 1992 in collaboration with Statistics Norway, which was responsible for sampling of participants and collection of data (Johansson et al, 1997). The total sample (n 1200, response rate 60%) was drawn according to procedures for random sampling.…”