A recent study showed that over a six-month period, ambulatory blood pressure measurement led to less intensive drug therapy and improved well-being compared with blood pressure measurement in the physician’s office; however, ambulatory monitoring did not reduce the cost of treatment. Self-measurement might lower costs and offer other advantages over office measurement. Staessen and colleagues, in the Treatment of Hypertension Based on Home or Office Blood Pressure (THOP) trial, compared self-measurement and conventional office measurements of blood pressure as guides to initiate and titrate antihypertensive drug treatment.
The THOP study was an international, multicenter, prospective trial that randomized hypertensive men and women who were without major cardiovascular complications or debilitating health problems to self-measurement or physician-office monitoring of blood pressure. Self-measured blood pressure was the average of all readings taken twice daily and collected during the seven days before each follow-up visit. All patients also had ambulatory testing at three separate intervals. The goal for both groups was a diastolic blood pressure of 80 to 89 mm Hg.
All patients began with or switched to lisinopril in a dosage of 10 mg per day and followed stepwise antihypertensive therapy. Blood pressure measurements were reviewed by physicians blinded to group assignment, and treatment recommendations were made accordingly in both groups by a field investigator. A questionnaire about symptoms was administered periodically to monitor well-being. Left ventricular mass was measured at the beginning and end of follow-up. Costs of treatments also were evaluated.
Among 400 randomized patients, the median follow-up was 350 days. More patients who monitored blood pressure at home rather than in the office were able to stop antihypertensive medication because their target diastolic pressure was reached and their blood pressure rate was stabilized. The ability to stop therapy related to the starting blood pressure in self-measuring patients, whereas baseline blood pressure in the office measurement group did not predict discontinuation of medication.
Initially, both groups had similar decreases in blood pressure. Drug treatment intensified in the office group, while in the home group systolic measurements were higher at two months, and diastolic blood pressure was higher at four months. At six months, both groups had similar decreases in blood pressure, after which blood pressure reduction was consistently and significantly greater among patients in the office group compared with the home group.
All patients had taken similar percentages of prescribed dosages of the study medications. The baseline adjusted changes for symptom score, which decreased from 1.52 to 1.40 in the office blood pressure group and from 1.60 to 1.50 in the home blood pressure group, were similar. Electrocardiographic and echocardiographic changes were small and statistically insignificant between groups. Overall, expenditure was slightly but significantly higher in the office blood pressure group than in the home blood pressure group.
In this one-year randomized trial, home blood pressure measurement resulted in less intensive drug therapy and marginally lower medical costs than office measurement, but it also led to less long-term control of blood pressure. No differences in symptoms or electrocardiographic or echocardiographic measures were noted between the groups. More patients in the home group were able to discontinue antihypertensive medication, presumably because patients with white-coat hypertension were identified.
Previous studies have shown that home blood pressure measurement improves the prognostic accuracy of office blood pressure. The authors suggest that because of increased blood pressure gradients between home and office measurements over time, patients who use home measurement should have lower blood pressure targets, probably below 130/80 mm Hg. However, the specific blood pressure targets for home measurement and discontinuation of therapy have yet to be established. The study’s findings support a stepwise approach to antihypertensive management that combines home monitoring with physician office visits. Home blood pressure measurement to the exclusion of office visits is not recommended.