Abstract 19178: Cost Effectiveness of Therapeutic Drug Monitoring in Facilitating BP Control in Resistant Hypertension
Nonadherence to antihypertensive medications is a major contributor to cardiovascular morbidity and mortality in the U.S. Recent studies have implicated Therapeutic Drug Monitoring (TDM) as a reliable method in monitoring adherence to antihypertensive medications in patients with resistant hypertension (RH) defined as BP 140/90 mmHg despite self-reported adherence to ≥ 3 antihypertensive drugs. However, the relationship between cost of testing and potential benefit of TDM in RH has not been assessed. We performed retrospective analysis of all new patients referred to the University of Texas Southwestern Medical Center Hypertension Clinic with RH between 2009-2012. Of 397 patients referred, 185 met criteria for RH. We found that 32 of 57 patients (57%) had undetectable serum levels of ≥ 1 drug screened, indicating medication nonadherence. Despite higher baseline BP (170/103 for non-adherent vs. 166/87 mmHg for adherent, p < 0.01), the magnitude of BP reduction was significantly greater for non-adherent vs. adherent patients (reduction in SBP 43±7/23±4 mmHg vs. 15±5/5±2 mmHg, p < 0.01) when the nonadherent patients were given feedback regarding their undetectable serum drug levels as part of their care. This greater reduction in BP was not explained by differences in treatment intensification (intensification score 0.02 for adherent vs -0.02 for non-adherent, p = 0.2). The median cost of TDM was $301 (224-544) in the non-adherent group vs. $277(140-375) in the adherent group (p = 0.2). Using bootstrap analysis with 1000 replication, we found the incremental cost per mmHg reduction in BP associated with TDM was $4.9, (3.8, 5.9), which is comparable to cost associated with many antihypertensive devices shown to be effective in reducing BP in resistant hypertension. In summary, our data suggested that therapeutic drug monitoring is cost effective in optimizing BP control in RH.
- © 2013 by American Heart Association, Inc.