Masked Uncontrolled Hypertension is Not Attributable to Medication Non-Adherence

Masked uncontrolled hypertension (MUCH) in treated hypertensive patients is defined as controlled automated office blood pressure (AOBP <135/85 mmHg) in clinic, but uncontrolled out-of-clinic BP by ambulatory blood pressure monitoring (ABPM; awake (daytime) readings ≥135/85 mmHg or 24-hr ≥130/80 mmHg). To determine if MUCH is attributable to antihypertensive medication non-adherence. 184 enrolled patients were confirmed to have controlled office BP, of these 167 patients were with adequate 24-hr ambulatory BP recordings. Out of 167 patients, 86 were controlled by in-clinic BP assessment, but had uncontrolled ambulatory awake BP, indicative of MUCH. The remaining 81 had controlled in-clinic and ambulatory awake BP, consistent with true controlled hypertension. After exclusion of 9 patients with missing 24-hr urine collections, antihypertensive medication adherence was determined based on detection of urinary drugs or drug metabolites by high-performance liquid chromatography-tandem mass spectrometry. Of the 81 patients with MUCH, 69 (85.2%) were fully adherent and 12 (14.8%) patients were partially adherent (fewer medications detected than prescribed). Of the 77 patients with true controlled hypertension, 69 (89.6%) were fully adherent with prescribed antihypertensive medications and 8 (10.4%) were partially adherent. None of the patients in either group were fully non-adherent. There was no statistically significant difference in complete or partial adherence between the MUCH and true controlled groups (p =0.403). Measurement of urinary drug and drug metabolite levels demonstrates a similarly high level of antihypertensive medication adherence in both MUCH and truly controlled hypertensive patients. These findings indicate that MUCH is not attributable to antihypertensive medication non-adherence.