Study Objectives: To determine characteristics associated with drug adherence and blood pressure control among patients with hypertension, and to assess agreement between self-reported and refill adherences.
Design: Cross-sectional analysis of baseline data from an ongoing randomized controlled trial.
Setting: Primary care center at an urban, county health system in Indianapolis, Indiana.
Objective: Data from electronic dosing monitors and published pharmacokinetic parameters were used to derive medication adherence measures for immediate-release metoprolol and examine their association with health care utilization of outpatients aged 50 years or older with heart failure.
Methods: We used a 1-compartment model and published population pharmacokinetic parameters to estimate mean plasma metoprolol concentrations for patients treated for 6 to 12 months. In the absence of directly measured plasma concentrations, we calculated the intended mean plasma concentration (Cp'(ave)) under the assumption of perfect adherence to the prescribed dose and frequency of administration.