When compared with ambulatory blood pressure measurements, conventional blood pressure measurements are not as highly reproducible, are associated with the so-called “white-coat effect” and must be repeated over a time interval (usually several weeks) in order to provide an idea of the patient's blood pressure range. Staessen and colleagues report on the Ambulatory Blood Pressure Monitoring and Treatment of Hypertension randomized trial that compared conventional and ambulatory blood pressure measurements in the management of hypertensive patients to determine the number and amount of antihypertensive drugs necessary for maintaining blood pressure control.
Patients were recruited from 47 family practices and nine internal medicine clinics. Patients already diagnosed as hypertensive were weaned from their blood pressure medications and began taking placebo once a day. Follow-up visits occurred at one and two months, and patients were then randomized if the last of three conventional diastolic blood pressure measurement readings taken at the follow-up visits averaged from 95 to 114 mm Hg. Once randomized, all patients began taking 10 mg of lisinopril daily. Patients were then seen at one, two, four and six months after randomization. Conventional blood pressure measurements, taken after the patient had been sitting for five minutes, were averaged over three consecutive readings. Signs, symptoms and blood pressure readings (both conventional and ambulatory) were then transmitted to an office where one physician made changes to the medication in a single-blind fashion. If the diastolic blood pressure was above the target range (i.e., higher than 89 mm Hg), the regimen was advanced one step. If the diastolic blood pressure was at the target range of 80 to 89 mm Hg, no change was made, and if diastolic blood pressure was below the target range (less than 80 mm Hg), the regimen was reduced one step. The steps were as follows: begin treatment with 10 mg of lisinopril daily (step 1); increase lisinopril to 20 mg daily (step 2); add 12.5 mg of hydrochlorothiazide daily (step 3); and add 5 mg of amlodipine daily (step 4).
A total of 544 patients enrolled in the study, and 419 were available for analysis. More patients who were managed using ambulatory blood pressure readings were able to discontinue their blood pressure medications, since their diastolic blood pressures stabilized at or below the target range. Of the 56 patients on ambulatory monitoring in whom drug treatment was stopped, more than one half (58.9 percent) had daytime diastolic blood pressure readings of less than 85 mm Hg. Symptom scores decreased similarly in both groups. The cost savings in the ambulatory blood pressure group (as a result of taking fewer medications and needing fewer physician visits) were offset by the higher cost of ambulatory monitoring. The changes in electrocardiographic and echocardiographic left ventricular mass were small and did not differ between the two groups.
The authors conclude that ambulatory blood pressure monitoring leads to less intensive antihypertensive treatment without a concomitant loss of blood pressure control or an increase in symptoms or left ventricular mass. Long-term prospective studies that include review of morbidity and mortality are warranted.