How accurate is your home blood pressure monitor? A small study conducted in Canada has concluded that too many home monitors do not measure blood pressure well enough.
Assessing the Accuracy of a Home Blood Pressure Monitor:
The investigators had 85 patients bring in their home blood pressure monitor. Each one was used to measure that person’s blood pressure in the clinic.
This was compared to blood pressure taken at the same time with a mercury sphygmomanometer, the gold standard device for blood pressure measurement. Two people were listening for the sounds and paying attention to the pressure measured with the sphygmomanometer.
Was There a Difference in Blood Pressure?
About 70 percent of the time, there was a 5 mm difference between the two measurements. Even more worrisome, the scientists found a 10 mm or greater difference for about 30 percent of the devices.
A home blood pressure monitor was most likely to diverge on its readings for systolic pressure. That is the higher number, and the one that is stated first in a standard report of blood pressure. In other words, when you say blood pressure is 120/80, the systolic pressure is 120.
The discrepancies were seen most frequently in men with large arms. Since arm size is known to affect the accuracy of blood pressure readings unless the cuff is well-matched to the arm size, this is not a big surprise. It does suggest that people should have more guidance when they are purchasing a home blood pressure monitor for themselves.