TABLE 6.

Strategies to monitor adherence in real time and for per-protocol analyses¹

Assessment method	Contribution to adherence detection	Level used to classify adherence vs nonadherence
Real-time adherence assessment
Food consumption in the presence of study personnel	Participants consume all or some (e.g., feeding studies, 1 main meal may be consumed onsite) of the total study food(s) in the presence of the study personnel.	Calculate percent study food consumed. Criteria for nonadherence should be established prior to study initiation.
Monitor body weight	If protocol is designed to be energy-balanced, weight should be relatively stable; if designed to be energy-deficient, weight should decline.	Assuming provided energy is accurately matched to energy expenditure (resting energy expenditure and physical activity), body-weight change anomalies indicate nonadherence. Criteria for nonadherence should be established prior to study initiation.
Daily/weekly monitoring forms	Participant reports deviations in intake [e.g., study food(s)/beverage(s) not consumed or non–study food(s)/beverage(s) consumed].	Days when deviation from the protocol is reported classified as nonadherent. Criteria for nonadherence should be established prior to study initiation.
Phone call/text/e-mail	Spot checks regarding questions/clarifications about adherence.	Criteria for nonadherence should be established prior to study initiation.
Adherence classification for per-protocol analyses
Daily monitoring or weekly monitoring forms	Deviations from protocol noted [e.g., study food(s)/beverage(s) not consumed or non–study food(s)/beverage(s) consumed].	Days where any deviation from the protocol is reported are classified as nonadherent. Prespecify criteria for triggering study withdrawal due to nonadherence (e.g., ≤90% of study days).
Dietary intake assessment	Data for the whole diet or consumption of specific foods captured.	Prespecify criteria for triggering study withdrawal due to nonadherence.
Urinary biomarker excretion
Dietary components that have nearcomplete excretion	24-h urinary sodium, potassium	Criteria for nonadherence should be established prior to study initiation.
Compounds added to study food(s) that have known percent excretion	24-h urinary PABA, riboflavin	Criteria for nonadherence should be established prior to study initiation.

¹PABA, para-aminobenzoic acid.