Retention Interval and Prompts: Creation and Cross-Sectional Pilot-Testing of Eight Interview Protocols to Obtain 24-Hour Dietary Recalls from Fourth-Grade Children.

Background: Any 24-hour dietary recall (24hDR) has a retention interval and prompts. No research has investigated their combined effect.

Objective: Eight 24hDR protocols, constructed by crossing two retention intervals (prior-24-hour recall obtained in afternoon and previous-day recall obtained in morning) with four prompts (forward [distant-to-recent], reverse [recent-to-distant], meal-name [eg, breakfast, lunch, etc], and open [no instructions]), were pilot-tested.

Design: Via a cross-sectional design, children were interviewed once, using one of eight 24hDR protocols.

Participants/setting: Forty-eight fourth-grade children (79% black; 50% girls; six per protocol) were randomly selected from two schools during spring 2011. Protocol assignment was random. Analyses excluded one interview due to protocol deviation.

Statistical Analyses Performed: Multivariate analysis of variance (MANOVA) with four nonaccuracy-related response variables was conducted, with independent variables retention interval, prompt, and their interaction. The significance level was 0.10 due to the study's exploratory nature.

Results: The response variable set differed across retention intervals (P=0.0003) and prompts (P=0.045) but not their interaction (P=0.11). Follow-up analysis of variance for each of four variables showed differences by retention interval for three and prompt for two: Interview length (minutes) differed by retention interval (prior-24-hour-afternoon=21.8, previous-day-morning=16.1; P<0.0008) and prompt (open=20.3, reverse=20.0, forward=19.1, and meal-name=16.3; P=0.079). Number of school meals reported eaten during the target period did not depend on retention interval or prompt, but was greater using meal-name prompts (1.7) than the other three prompts (1.3; P=0.055; contrast t test). Number of 10 possible meal components reported eaten at school meals differed by retention interval (prior-24-hour-afternoon=4.1, previous-day-morning=2.9; P=0.048). Weighted number of items (condiment=0.33, combination entrée=2.0, and else=1.0) reported eaten at school meals differed by retention interval (prior-24-hour-afternoon=5.8, previous-day-morning=4.1; P=0.079) and prompt (forward=6.2, meal-name=5.3, reverse=4.9, and open=3.3; P=0.093).

Conclusions: Children's nonaccuracy-related responses to eight 24hDR protocols varied as hypothesized. The selected protocols will be useful in a planned validation study to investigate differences by protocol in children's recall accuracy.