An evaluation of the sensitivity and specificity of energy expenditure measured by heart rate and the Goldberg cut-off for energy intake: basal metabolic rate for identifying mis-reporting of energy intake by adults and children: a retrospective analysis.

OBJECTIVE: To identify adults and children as under- (UR), acceptable (AR), or over-reporters (OR) of energy intake (EI) using energy expenditure measured by doubly labelled water (DLW) (EE(DLW)), and to use this as a reference to determine the sensitivity and specificity of (i) EE measured by heart rate (EE(HR)), and (ii) the Goldberg cut-off technique for classifying subjects into the same categories.
DESIGN: Retrospective analysis of a dataset comprising concurrent measurements of EE(DLW), EE(HR), basal metabolic rate (BMR), and EI by weighed record (EI(WR)) on 14 adults and 36 children. EI by diet history (EI(DH)) was also measured in the children only. EI(WR):EE(DLW) provided the reference definition of subjects as UR, AR or OR. Three strategies for classifying mis-reporters based on EE(HR) and Goldberg cut-offs were then explored. Sensitivity and specificity were calculated respectively as the proportion of UR and non-UR correctly identified.
RESULTS: Approximately 80% of all subjects were AR. For EI(WR) and EI(DH) respectively, the sensitivity of EE(HR) was 0.50 and 1.00, and specificity was 0.98 and 1.00. Although designating subjects as having low, medium or high activity levels (EE(HR):BMR(meas)) and calculating cut-offs based on appropriate WHO physical activity level PALs did not change sensitivity, specificity dropped to 0.98 (EI(WR)) and 0.97 (EI(DH)). Cut-offs based on a PAL of 1.55 reduced sensitivity to 0.33 (EI(WR)) and 0.00 (EI(DH)), but specificity remained unchanged. The sensitivity of all cut-offs based on physical activity level (PALs) for EI(WR) was 0.50 (adults) and 0.25 (children).
CONCLUSIONS: If the precision of EE(HR) was improved, it may be useful for identifying mis-reporters of EI.