Measurement of medication compliance in a clinical setting. Comparison of three methods in patients prescribed digoxin

Abstract

Medication compliance is an important medical process, and useful methods are needed to measure compliance in clinical practice. Interview, pill count and serum digoxin concentration (SDC) were compared in 173 patients prescribed digoxin to determine feasiblity, ease, timeliness; reasons for noncompliance; and validity of interview and pill count compared with SDC. All patients were interviewed; among 33 (19%) not taking their medication correctly, 9 (5%) did not know how. Pill counts were possible for 68 patients (39%). One patient had a correct pill count. Steady-state SDC were obtained for 143 patients (83%) but were not available during patients'' visits. The SDC for 25 patients were < 0.50 ng/ml. Interviews correlated with SDC pill counts did not. Pill counts and SDC required telephoning patients before appointments. In clinical practice, interview may be the most useful method of measuring medication compliance.