Use of electronic adherence with PK parameters to predict outcomes of older adult heart failure patients.

Abstract

Data from electronic dosing monitors may be used in conjunction with the pharmacokinetics (PK) of a monitored drug and could predict health outcomes. We derived an adherence metric modeling the estimated mean serum concentration of metoprolol Cp (Cpave) from standard PK parameter values of the study drug (ka and k) and times of administration from electronic dosing monitors. A target serum concentration (Cṕave) was determined using the same model assuming perfect adherence to the prescribed dose and administration schedule i.e. perfect adherence. The difference Δ= Cṕave −Cpave represented the deviation from the target Cp and was used as the new kinetic‐derived adherence measure with a larger Δ representing a greater gap between prescribed and actual serum concentrations resulting from poorer adherence. We analyzed the electronic monitor records of 80 older heart failure patients who had been prescribed metoprolol. The mean of Δ was 8.2 ng/ml (SD=9.9). Δ correlated negatively with the percentage of dose taken (ρ=−0.5075) and the percentage dose taken on schedule (ρ= −0.3813). Log‐linear models adjusted for functional severity indicated that Δ strongly predicted the numbers of patient hospitalizations and emergency visits (p<0.0001). The new adherence measure summarizes gaps between the targeted and actual metoprolol serum concentration using data from electronic dosing monitors and predicts health outcomes of older adult patients with heart failure. Clinical Pharmacology & Therapeutics (2004) 75, P76–P76; doi: