Abstract
A low-cost, ambulatory blood-pressure monitor has been calibrated and validated against a random zero sphygmomanometer. The repeatability of ambulatory pressure recordings after a placebo month in 44 mild to moderate untreated hypertensives was assessed. Systolic blood pressure showed a mean difference over 1 month of 2.0 mmHg, with a standard deviation of differences of 9.3 mmHg. The diastolic blood pressure mean difference was 0.1 mmHg (SD=6.3 mmHg). This variability was much less than for clinic readings (SD=17.3 mmHg) or for single home pressure readings (SD=19.7 mmHg). Using ambulatory monitoring to detect a drop in pressure of 8/5 mmHg with a power of 0.9, the number of subjects needed in a parallel group trial is reduced from 360 to 68, and in a crossover study from 88 to 16 subjects. The usefulness of ambulatory pressure monitoring is demon-strated in a placebo-controlled comparisom of atenolol, nifedipine retard, or their combination in random order. Eleven subjects, 21-60 years, with initial average blood pressures of 166.5/104.7 mmHg, showed a reduction in pressure with atenolol 50 mg a day of 15.1/10.0 mmHg, with nifedipine retard 20 mg b.i.d. of 21.0/11.6 mmHg, and with atenolol 50 mg and nifedipine retard 20 mg once a day of 26.2/16.8 mmHg. Ambulatory monitoring of pressure improved the accuracy of the trial and demonstrated a reduction in the alerting response with atenolol.
Original language | English (US) |
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Pages (from-to) | 303-311 |
Number of pages | 9 |
Journal | Cardiovascular Drugs and Therapy |
Volume | 3 |
Issue number | 1 Supplement |
DOIs | |
State | Published - Jun 1989 |
Keywords
- ambulatory blood pressure
- atenolol
- beta-blockers
- calcium antagonists
- hypertension
- nifedipine
- statistical power
- trial design
ASJC Scopus subject areas
- Pharmacology
- Cardiology and Cardiovascular Medicine
- Pharmacology (medical)