Related Experiment Videos
Ambulatory blood pressure monitoring in clinical trials
J Staessen1, R Fagard, P Lijnen
1Department of Pathophysiology, University of Leuven, Belgium.
Insights
Ambulatory blood pressure monitoring (ABPM) offers accurate hypertension assessment, avoiding the white-coat effect. This method enhances clinical trial power and simplifies study designs by minimizing placebo effects.
Area of Science:
- Cardiology
- Hypertension Research
- Clinical Trials
Background:
- Traditional hospital blood pressure readings are prone to the 'white-coat effect'.
- Ambulatory blood pressure monitoring (ABPM) provides more frequent, longer-term readings.
- ABPM improves blood pressure estimation accuracy and statistical power in hypertension trials.
Purpose of the Study:
- To evaluate the utility of ABPM in clinical trials for hypertension.
- To establish normal reference ranges for 24-hour, daytime, and nighttime blood pressure.
- To assess the presence of placebo effects in ABPM studies.
Main Methods:
- Meta-analysis of 23 studies involving 3304 normotensive subjects.
- Analysis of 24-hour, daytime, and nighttime ambulatory blood pressure readings.
- Review of studies investigating placebo effects in ABPM.
Main Results:
- Mean 24-hour ambulatory blood pressure was 118/72 mmHg.
- Hypertension suggested if 24-hour pressure > 129/87 mmHg (or daytime/nighttime equivalents).
- Placebo effects on blood pressure appear minimal with ABPM.
Conclusions:
- ABPM is valuable for detecting white-coat hypertension and enhancing trial accuracy.
- Established reference ranges aid in diagnosing hypertension.
- The lack of placebo effects may simplify hypertension trial designs.
Abstract:
Monitoring ambulatory blood pressure, instead of taking pressure readings in hospital, avoids the so-called white-coat effect and allows more readings to be obtained over a longer period of time. It improves the accuracy of the blood pressure estimate and increases the statistical power of therapeutic trials for hypertension. Subjects with white-coat or office hypertension can be detected by ambulatory blood pressure monitoring and excluded from clinical trials. In 23 studies, including a total of 3304 normotensive subjects, the 24-h ambulatory blood pressure averaged 118/72 mmHg; the daytime and night-time pressures were 123/76 mmHg and 106/64 mmHg, respectively. If the mean plus two standard deviation (s.d.) interval is considered the upper limit of normal, the meta-analysis suggested that hypertension may be suspected if the 24-h pressure exceeds 129/87 mmHg, or if the daytime or night-time pressures are higher than 146/91 mmHg or 127/79 mmHg, respectively. On balance, most studies suggest that placebo effects on blood pressure are not observed when blood pressure is measured with ambulatory recorders. If confirmed, this observation indicates that it is possible to simplify the design of trials in the field of hypertension. Ambulatory blood pressure readings should be obtained with properly validated monitors. If the recordings are of sufficient quality, editing does not increase the precision of the subsequent statistical analyses. The statistical analyses should account for diurnal rhythms, and subject and treatment effects.