Is ambulatory blood pressure monitoring cost-effective in the routine surveillance of treated hypertensive patients in primary care?

Achieving target levels of office and/or ambulatory blood pressure readings among treated hypertensive patients is an important aspect of cardiovascular disease prevention. Although office blood pressure measurement is simple and convenient, ambulatory blood pressure monitoring is especially useful for identifying patients with 'white coat' hypertension, in whom falsely raised office blood pressure recordings often lead to unnecessary return visits and additional treatment. Office and ambulatory blood pressure control was compared in 374 treated hypertensive patients in a single general practice, and the costs of performing annual ambulatory blood pressure measurements were compared with potential clinical savings. Ambulatory blood pressure monitoring detected 115 (31%) patients who fulfilled the British Hypertension Society target for ambulatory but not office blood pressure, i.e. white coat hypertension, and 21 patients apparently controlled by office but not ambulatory blood pressure criteria. In economic modelling, the capital, maintenance and user costs of ambulatory blood pressure monitoring (13,790 Pounds per year) were partly offset by fewer follow-up visits and second-line treatments in the group with white coat hypertension (there were modelled savings of 10,178 Pounds). Thus, ambulatory blood pressure monitoring identified a much larger number of treated hypertensive patients with adequate blood pressure control at an extra net cost of 3612 Pounds per year.