Directly Observed Therapy Effective for Treatment-Resistant Hypertension

Doctor handing a patient a glass of water and pill
Regular assessment of adherence to blood pressure-lowering drugs as well as directly observed therapy may be helpful for resolving treatment-resistant hypertension.

A study found that regular assessment of adherence to blood pressure (BP)-lowering drugs as well as directly observed therapy (DOT) may be helpful for resolving treatment-resistant hypertension in a subset of patients. The findings from the study were published in JAMA Internal Medicine.

Patients with treatment-resistant hypertension were enrolled in an observational cohort if they presented with a daytime mean systolic BP of 135 mm Hg or greater on 24-hour ambulatory blood pressure monitoring (N=48). Only patients who were receiving 3 or more antihypertension therapies were included (mean age, 62.1 years). The investigators assessed adherence to prescribed BP-lowering drugs 6 months before enrollment, using clinician questioning, pharmacy filling records, and pill count.

Prescribed BP-lowering drugs were administered to patients on the day of DOT, and a 24-hour BP monitoring assessment was performed after patients reached the peak treatment effect as well as at 1-month follow-up. The proportion of patients with a daytime mean systolic BP of less than 135 mm Hg after DOT and at 1 month comprised the primary and secondary outcomes, respectively.

Immediately after DOT, 71% (n=34) of patients who had a decrease in systolic BP of 3 mm Hg had a consistent daytime systolic BP of 135 mm Hg or greater. A total of 14 (29%) participants experienced resolution of treatment-resistant hypertension and a reduction in systolic BP of 26 mm Hg. At 1-month follow-up, 30% (n=14) of the 46 remaining patients were free of treatment-resistant hypertension.

Limitations of the study include the small number of participants, the single-center design, and the highly selected nature of the patient population.

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“The use of DOT as described here was strictly dichotomous (adherence vs nonadherence) and thus does not allow for precise assessment of the degree of nonadherence (eg, partial vs complete),” the researchers wrote, “as may be the case with therapeutic drug monitoring.”


The authors report disclosures with the Physicians Services Incorporated and The Ottawa Hospital Academic Medical Organization–Innovation Fund Provincial Oversight Committee, among other organizations (reported in the study paper).


Ruzicka M, Leenen FHH, Ramsay T, et al. Use of directly observed therapy to assess treatment adherence in patients with apparent treatment-resistant hypertension [published online June 17, 2019]. JAMA Intern Med. doi:10.1001/jamainternmed.2019.1455.