Journal of Behavioral Medicine, Vol. 8, No. 3, 1985 Riboflavin as a Tracer of Medication Compliance Patricia M. Dubbert, ~ Abby King, ~ Stephen R. Rapp, 1 Deborah Brief, ~ John E. Martin, ~ and Mary Lake ~ Accepted for publication: March 5, 1984 Three experiments were conducted to evaluate the accuracy of urine ultraviolet fluorescent tests for riboflavin, which has been used as a tracer for medication compliance in several clinical drug trials. Observer accuracy in discriminating ribofiavin-positive or negative urine samples was found to vary with the method of observation, dose of riboflavin, observer ex- perience, and time postingestion. The results showed that, while the 5-rag dose used in previous clinical trials was too small to permit reliable assess- ment of compliance, larger doses of riboflavin could produce nearly 100% accuracy for minimally trained observers who used a matching-to-sample observation procedure. The findings are discussed in terms of the potential clinical and research applications of this type of simple but reliable com- pliance assessment procedure. KEY WORDS: medication; compliance; adherence; riboflavin. INTRODUCTION The failure of as many as 50% of patients on long-term regimens to take their medications as prescribed leads to significant problems in clinical practice and in interpreting the results of controlled trials for drug treatments (Haynes et aL, 1979). A number of compliance-enhancement This research was supported by the Medical Research Service of the Veterans Administration, Health Services Research and Development Grant Award 4187-003 to John E. Martin. Weterans Administration and University of Mississippi Medical Centers, Jackson, Mississippi 39216. 287 0160-7715/85/0900-0287504.50/0 9 1985Plenum Publishing Corporation