Procedures for screening out inaccurate reports of dietary energy intake

OBJECTIVE: To review existing methods and illustrate the use of a new, simple method for identifying inaccurate reports of dietary energy intake (rEI). DESIGN: Comparison of rEI with energy requirements estimated by using total energy expenditure predicted (pTEE) from age, weight, height and sex using a previously published equation. Propagation of error calculations was performed and cut-offs for excluding rEI at plus or minus two standard deviations (+/-2 SD) and +/-1 SD for the agreement between rEI and pTEE were established. SETTING: Dietary survey in a US national cohort: the Continuing Survey of Food Intakes by Individuals (CSFII), 1994-96. SUBJECTS: Men and non-pregnant, non-lactating women aged 21-45 years in the CSFII who provided two multiple-pass 24-hour recalls, height and weight (n = 3755). RESULTS: Average rEI was 77% of pTEE in men, and 64% of pTEE in women. Calculated cut-offs were rEI <40% or >160% of pTEE (+/-2 SD) and <70% or >130% of pTEE (+/-1 SD), respectively. Use of only the +/-1 SD cut-offs, not the +/-2 SD cut-offs, resulted in a relationship between rEI and body weight similar to what was expected (based on an independently calculated relationship between rEI and measured TEE). Exclusion of rEI outside either the +/-2 SD (11% of subjects) or +/-1 SD (57% of subjects) cut-offs did not affect mean reported macronutrient intakes, but did markedly affect relationships between dietary composition and body mass index. CONCLUSIONS: When examining relationships between diet and health, use of +/-1 SD cut-offs may be preferable to +/-2 SD cut-offs for excluding inaccurate dietary reports.