How reliable are self-measured blood pressures taken at home?
Recommendations from others
In addition to diagnosing white-coat hypertension, World Health Organization/International Society of Hypertension Guidelines Committee has recommended that home blood pressure measurement is useful in the following circumstances:9
- unusual variability of blood pressure over the same or different visits
- office hypertension in subjects with low cardiovascular risk
- symptoms suggesting hypotensive episodes
- hypertension resistant to drug treatment.
Standardization and validation protocols are available from the Association for the Advancement of Medical Instrumentation,10 European Hypertension Society,11 or the British Hypertension Society (available at www.hyp.ac.uk/bhs/bp_ monitors/automatic.htm). Relatively few of the hundreds of available blood pressure measurement devices available meet these criteria. The most current Association for the Advancement of Medical Instrumentation standards are labeled as ANSI/AAMI-SP10:2002/A1:2003 standards. Table 2 lists some devices that meet the various protocols. Devices in this market change rapidly, so buyers should confirm the device they are evaluating meets current standards.
TABLE 2
Devices that meet standards for home BP measurement
| SMBP device suitable for home use | Validation protocol |
|---|---|
| A&D-767 | BHS |
| A&D-779 | International Protocol |
| A&D-787 | International Protocol |
| OMRON M5-I | International Protocol |
| OMRON 705IT | International Protocol |
| OMRON 705 CPII | International Protocol |
| OMRON MIT | BHS |
| Microlife 3BTO-A | BHS |
| Microlife 3AG1 | BHS |
| BHS: British Hypertension Society; International Protocol: European Hypertension Society | |
Self-measured BP may help us better diagnose and manage hypertension
Paul Pisarik, MD, MPH
Baylor College of Medicine, Houston, Tex
It has been shown that office blood pressure readings can give false-positive results in those who have “white coat hypertension” and give false-negative readings in those with “white coat normotension” or “masked hypertension”—patients who have normal blood pressure values in the office, but elevated blood pressure values outside the office. This is not a trivial issue. Ten to 20% of patients with normal blood pressure values in the office have elevated blood pressure values throughout the day, and evidence is beginning to mount that the cardiovascular consequences are the same for these patients as for those with sustained hypertension.1
The SHEAF trial (and other studies) have thrown another complexity into hypertension control by showing that OBP readings were inaccurate in 22% of treated hypertensive patients—13% had uncontrolled OBP with normal SMBP, and 9% had normal OBP but uncontrolled SMBP.3
Thus, SMBP is a potentially very powerful and cost-effective tool that may help us better diagnose and manage this complex disease. I have encouraged my hypertensive patients to do SMBP and, as one who has white-coat hypertension (and a strong family history of hypertension), I am diligent at taking my own SMBP on a regular basis to guard against the insidious onset of this disease.
