The potential disadvantage of using a TDM-guided PA screening strategy is that investigation for PA in the nonadherent subset of patients with TRH may be overlooked or delayed. However, the overall proportion of PA missed with the TDM-guided approach compared with unselective routine screening was small, at only 3.8% of patients. Furthermore, the current AHA guidelines do not recommend further investigation for secondary hypertension for patients who are nonadherent to treatment because behavioral intervention to improve nonadherence is more likely to improve BP control. The recommendation is supported by our recent study indicating that, when nonadherent patients were given TDM-guided feedback regarding specific undetectable serum drug levels and provided counseling to overcome barriers to adherence, BP improved substantially at subsequent visits without treatment intensification. Thus, TDM may significantly
improve adherence in initially nonadherent patients as a behavioral intervention, helping identify patients with true TRH as potential targets for investigation for
secondary hypertension. It is important to note that, in our hypertension specialty clinic, the nonadherent
patients continue to receive medical therapy including mineralocorticoid receptor antagonists, which are considered the fourth-line drug therapy for TRH patients with or without primary aldosteronism. Furthermore, initially nonadherent patients who continue to have uncontrolled hypertension after adherence is improved following behavioral intervention are subjected to PA screening in the same fashion as the initially adherent patients in our clinic. The modest potential delay in a secondary hypertension workup in patients with true TRH or pseudo-resistant hypertension would likely be completely outweighed by the lower cost and diagnostic efficiency of minimizing unnecessary testing
in nonadherent patients.