Hypertension is a common problem in Canada with a prevalence of about 15%. The goal of hypertension therapy should be to maximize blood pressure control. Home blood pressure monitoring (HBPM) devices are available and many patients are using them. The role that self-monitoring of blood pressure can play in optimizing blood pressure control is unclear. We hope to clarify the role of home blood pressure monitoring in the treatment of hypertension and explore how it may affect patient and physician behaviours related to blood pressure management. This study will compare a group of hypertensive patients who use HBPM with those who do not use these devices. The intervention (HBPM) group will measure their blood pressure at home a minimum of once weekly and will report these measurements to their family doctor at each visit. The control group will receive usual care as delivered by their family doctor. Outcomes of blood pressure control will be measured over a 12 month period. Outcomes will be determined primarily by 24 hour ambulatory blood pressure monitoring and by reviewing data in patient's charts located in family physicians office. Fifty family physicians from the Kingston area have agreed to participate.

The objective of this study is to measure the effect of home (self) blood pressure monitoring on control of hypertension in a primary care setting.

This research is important for several reasons:

i) Lack of control of hypertension is common and is associated with morbidity and mortality.

ii) The costs of managing hypertensions are high, not only because of the prevalence of hypertension, but also because maintenance of control must exist over many years for most patients.

iii) Home blood pressure monitoring is increasingly being used by patients.

iv) Guidelines for home blood pressure monitoring are already being developed and distributed.

v) While it would seem helpful to increase self-care by patients, there is currently conflicting or inadequate evidence that home monitoring is useful.

The main hypothesis of the study is that, compared to patients who receive usual care, patients who use home monitoring will have lower blood pressure levels.

Our secondary hypothesis is that HBPM changes physician and patient behaviours in ways that would result in better control of hypertension.

The methodology uses cluster randomization. Physicians will be randomly allocated to either have their patients use the intervention or to continue with usual care. The intervention for the experimental group is the provision of a home blood pressure monitor to patients with a request that they record weekly blood pressure measurements and report them to their family physician at their regular hypertension follow-up visits. The physicians will be informed of current guidelines for target levels for home monitored blood pressure. The control group will receive usual care.

The main outcome measures will be blood pressure level (by 24 hour ambulatory monitoring) at baseline, 6 months and 12 months.

The secondary objective of this study is to measure the effect of home monitoring on physicians' and patients' behaviours related to hypertension control. Behaviours that will be measured include the intensity and type of pharmacological treatment, compliance with antihypertensive medication and changes in patient's lifestyle.

Inclusion Criteria:

• adults age 18 years and older with essential hypertension.
• who are treated with medication to lower their blood pressure.
• whose mean daytime blood pressure at enrolment is 135/85 mm Hg or greater.
• and who are not currently using HBPM.

Exclusion Criteria:

• a diagnosis of secondary hypertension.
• pregnancy.
• hypertension management primarily by a consultant.
• a disability that precludes use of a home blood pressure monitor.
• enrolled in another hypertension trial
• white coat hypertension