Directly Observed Therapy in Hypertension (DOT-HTN)

Medical Measures in Hypertensives Considered Resistant

BACKGROUND

Patients with resistant hypertension are the group of hypertensive patients with the highest cardiovascular risk.

METHODS

All rules and guidelines for treatment of hypertension should be followed strictly to obtain blood pressure (BP) control in resistant hypertension. The mainstay of treatment of hypertension, also for resistant hypertension, is pharmacological treatment, which should be tailored to each patient's specific phenotype. Therefore, it is pivotal to assess nonadherence to pharmacological treatment as this remains the most challenging problem to investigate and manage in the setting of resistant hypertension.

RESULTS

Once adherence has been confirmed, patients must be thoroughly worked-up for secondary causes of hypertension. Until such possible specific causes have been clarified, the diagnosis is apparent treatment-resistant hypertension (TRH). Surprisingly few patients remain with true TRH when the various secondary causes and adherence problems have been detected and resolved. Refractory hypertension is a term used to characterize the treatment resistance in hypertensive patients using ≥5 antihypertensive drugs. All pressor mechanisms may then need blockage before their BPs are reasonably controlled.

CONCLUSIONS

Patients with resistant hypertension need careful and sustained follow-up and review of their medications and dosages at each term since medication adherence is a very dynamic process.

Nonadherence by Serum Drug Analyses in Resistant Hypertension: 7-Year Follow-Up of Patients Considered Adherent by Directly Observed Therapy

Background Measurement of serum concentrations of drugs is a novelty found useful in detecting poor drug adherence in patients taking ≥2 antihypertensive agents. Regarding patients with treatment-resistant hypertension, we previously based our assessment on directly observed therapy. The present study aimed to investigate whether serum drug measurements in patients with resistant hypertension offer additional information regarding drug adherence, beyond that of initial assessment with directly observed therapy. Methods and Results Nineteen patients assumed to have true treatment-resistant hypertension and adherence to antihypertensive drugs based on directly observed therapy were investigated repeatedly through 7 years. Serum concentrations of antihypertensive drugs were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry from blood samples taken at baseline, 6-month, 3-year, and 7-year visits. Cytochrome P450 polymorphisms, self-reported adherence and beliefs about medicine were performed as supplement investigations. Seven patients (37%) were redefined as nonadherent based on their serum concentrations during follow-up. All patients reported high adherence to medications. Nonadherent patients expressed lower necessity and higher concerns regarding intake of antihypertensive medication (P=0.003). Cytochrome P450 polymorphisms affecting metabolism of antihypertensive drugs were found in 16 patients (84%), 21% were poor metabolizers, and none were ultra-rapid metabolizers. Six of 7 patients redefined as nonadherent had cytochrome P450 polymorphisms, however, not explaining the low serum drug concentrations measured in these patients. Conclusions Our data suggest that repeated measurements of serum concentrations of antihypertensive drugs revealed nonadherence in one-third of patients previously evaluated as adherent and treatment resistant by directly observed therapy, thereby improving the accuracy of adherence evaluation. Registration URL: https://www.clinicaltrials.gov; unique identifier: NCT01673516.

Adherence in Hypertension

The global epidemic of hypertension is largely uncontrolled and hypertension remains the leading cause of noncommunicable disease deaths worldwide. Suboptimal adherence, which includes failure to initiate pharmacotherapy, to take medications as often as prescribed, and to persist on therapy long-term, is a well-recognized factor contributing to the poor control of blood pressure in hypertension. Several categories of factors including demographic, socioeconomic, concomitant medical-behavioral conditions, therapy-related, healthcare team and system-related factors, and patient factors are associated with nonadherence. Understanding the categories of factors contributing to nonadherence is useful in managing nonadherence. In patients at high risk for major adverse cardiovascular outcomes, electronic and biochemical monitoring are useful for detecting nonadherence and for improving adherence. Increasing the availability and affordability of these more precise measures of adherence represent a future opportunity to realize more of the proven benefits of evidence-based medications. In the absence of new antihypertensive drugs, it is important that healthcare providers focus their attention on how to do better with the drugs they have. This is the reason why recent guidelines have emphasize the important need to address drug adherence as a major issue in hypertension management.