Riboflavin as an independent and accurate biomarker for adherence in a randomized double-blind and placebo-controlled clinical trial.

Background:Medication adherence is critical for success of clinical trials. Objective:To assess oral riboflavin is an adherence marker. Methods:Riboflavin was incorporated into active treatment and placebo pills for a clinical trial lasting for 2 years. Results:The accuracy (area under the receiver operating curve) of urinary riboflavin was 0.91 as a binary classifier of adherence, and was similar or better than for two active study ingredients daidzein (0.92) and genistein (0.87) (allp < 0.0001). Decreased adherence over time was similar in the two study groups. Conclusion: Riboflavin is an accurate and useful biomarker for study pill ingestion. [ABSTRACT FROM PUBLISHER]