Validity and reliability of an online self-report 24-h dietary recall method(Intake24): a doubly labelled water study and repeated-measures analysis†

Abstract

Online self-reported 24-h dietary recall systems promise increased feasibility of dietary assessment. Comparison against interviewer-led recalls established theirconvergent validity; however, reliability and criterion-validity information is lacking. The validity of energy intakes (EI) reported using Intake24,anonline24-hrecall system, was assessed against concurrent measurement of total energy expenditure (TEE) using doubly labelled water in ninety-eight UK adults(40–65years). Accuracy and precision of EI were assessed using correlation and Bland–Altman analysis. Test–retest reliability of energy and nutrient intakes wasassessed using data from three further UK studies where participants (11–88 years) completed Intake24 at least four times; reliability was assessed usingintra-class correlations (ICC). Compared with TEE, participants under-reported EI by 25 % (95 % limits of agreement−73 % to +68 %) in thefirst recall,22 % (−61 % to +41 %) for average offirst two, and 25 % (−60 % to +28 %) forfirst three recalls. Correlations between EI and TEE were 0·31 (first), 0·47(first two) and 0·39 (first three recalls), respectively. ICC for a single recall was 0·35 for EI and ranged from 0·31 for Fe to 0·43 for non-milk extrinsic sugars(NMES). Considering pairs of recalls (first twov.third and fourth recalls), ICC was 0·52 for EI and ranged from 0·37 for fat to 0·63 for NMES. EI reportedwith Intake24 was moderately correlated with objectively measured TEE and underestimated on average to the same extent as seen with interviewer-led24-hrecalls and estimated weight food diaries. Online 24-h recall systems may offer low-cost, low-burden alternatives for collecting dietary information.