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Therapeutics

Ambulatory blood pressure monitoring allowed more patients to stop antihypertensive drug therapy

ACP J Club. 1998 May-June;128:64. doi:10.7326/ACPJC-1998-128-3-064


Source Citation

Staessen JA, Byttebier G, Buntinx F, et al. Antihypertensive treatment based on conventional or ambulatory blood pressure measurement.A randomized controlled trial. JAMA. 1997 Oct 1;278:1065-72.


Abstract

Objective

To determine whether ambulatory blood pressure (ABP) monitoring in patients with hypertension leads to less intensive antihypertensive drug treatment than conventional sphygmomanometer blood pressure (CBP) monitoring.

Design

Randomized controlled trial with 6-month follow-up.

Setting

47 family practices and 9 internal medicine outpatient clinics in Belgium.

Patients

419 patients (mean age 53 y, 54% women) who completed a 4- to 8-week drug washout period. Inclusion criteria were an average sitting diastolic blood pressure (BP) of 95 to 114 mm Hg on the basis of 3 consecutive conventional BP readings, age ≥ 18 years, and effective contraception in women of child-bearing age. Patients were excluded if stopping antihypertensive drug treatment was contraindicated (e.g., patients with overt heart failure or unstable angina) or if the patient worked night shifts. Follow-up was 93%.

Intervention

213 patients were allocated to average daytime ABP monitoring (every 15 min from 10:00 a.m. to 8:00 p.m.), and 206 were allocated to CBP monitoring on the basis of an average of 3 sphygmomanometer readings while sitting. All patients began receiving lisinopril, 10 mg/d. During follow-up visits at 1, 2, 4, and 6 months, possible treatment decisions (increase lisinopril dose to 20 mg/d; add hydrochlorothiazide, 12.5 mg in the morning; or add amlodipine, 5 mg/d) were made by 1 physician blinded to study assignment.

Main outcome measures

Stopping treatment was defined as discontinuing therapy during the study because diastolic BP was < 80 mm Hg and remained at or below 80 to 89 mm Hg at 6 months. A cost analysis was also done.

Main results

More patients in the ABP group than in the CBP group could stop drug treatment (26.3% vs 7.3%, P < 0.001), and fewer patients in the ABP group than in the CBP group moved to sustained multiple-drug treatment (27.2% vs 42.7%, P < 0.001). No difference was seen in the overall cost of ABP and CBP monitoring (mean cost ratio -3.3, 95% CI -12.7 to 6.1).

Conclusions

More patients who had ambulatory blood pressure monitoring could stop antihypertensive drug treatment, and fewer of these patients progressed to sustained treatment with multiple antihypertensive drugs compared with patients who had conventional sphygmomanometer monitoring. No differences were found, however, in overall cost.

Sources of funding: ZENECA Inc (Destelbergen, Belgium). Medication donated by ZENECA and Roerig-Pfizer (Brussels, Belgium).

For article reprint: Dr. J.A. Staessen, Klinisch Laboratorium Hypertensie, Inwendige Geneeskunde-Cardiologie, U.Z. Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. FAX 32-16-347106.


Commentary

For at least the past 15 years, the role of ABP monitoring in the management of hypertension has been unclear. Initially, there was justifiable concern about device accuracy and reproducibility of results. Later, concerns focused on whether ABP results would correlate with hypertensive complications and with BP measured in the office.

The study by Staessen and colleagues confirms both the validity of ABP monitoring and the strength of correlation with a common complication of hypertension, left ventricular hypertrophy. ABP monitoring predicted which patients would develop left ventricular hypertrophy and freed many patients from unnecessary medications. Long-term follow-up of the patients who discontinued drug therapy will be important to ascertain whether sustained hypertension will develop later in life and require more careful monitoring.

The study design is particularly robust. Drug therapy was tapered in all patients before the trial, and all medication adjustments were made by a blinded independent observer. The financial analysis may not apply to current medical practice in the United States or Canada because of differences in the economic structure of medical fees and follow-up costs between these countries and Belgium. In addition, the use of lisinopril as the first line of treatment instead of a thiazide diuretic increased the cost savings of avoiding medication. Nevertheless, patients place a high value on avoiding unnecessary treatment and follow-up visits.

Where does ABP monitoring fit in? It seems to be most clinically useful in patients with suspected white-coat hypertension, apparent drug resistance, episodic hypertension, hypotensive symptoms, or suspected autonomic dysfunction. Current insurance coverage for ABP monitoring is minimal, and clinicians will want to limit its use to those patients most likely to benefit.

David L. Bronson, MD
Cleveland Clinic FoundationCleveland, Ohio, USA