Potential cost-effectiveness of therapeutic drug monitoring in patients with resistant hypertension

Background: Nonadherence to drug therapy poses a significant problem in the treatment of patients with presumed resistant hypertension. It has been shown that therapeutic drug monitoring (TDM) is a useful tool for detecting nonadherence and identifying barriers to treatment adherence, leading to effective blood pressure (BP) control. However, the cost-effectiveness of TDM in the management of resistant hypertension has not been investigated. Method: A Markov model was used to evaluate life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios in resistant hypertension patients receiving either TDM optimized therapy or standard best medical therapy. The model ran from the age of 30 to 100 years or death, using a cycle length of 1 year. Efficacy of TDM was modeled by reducing risk of hypertension-related morbidity and mortality. Cost analyses were performed from a payer's perspective. Deterministic and probabilistic sensitivity analyses were conducted. Results: In the age group of 60-year olds, TDM gained 1.07 QALYs in men and 0.97 QALYs in women at additional costs of (sic)3854 and (sic)3922, respectively. Given a willingness-to-pay threshold of (sic)35 000 per QALY gained, the probability of TDM being cost-effective was 95% or more in all age groups from 30 to 90 years. Results were influenced mostly by the frequency of TDM testing, the rate of nonresponders to TDM, and the magnitude of effect of TDM on BP. Conclusion: Therapeutic drug monitoring presents a potential cost-effective healthcare intervention in patients diagnosed with resistant hypertension. Importantly, this finding is valid for a wide range of patients, independent of sex and age.