Q: I recently heard a report on the news about a new study that said home blood-pressure monitors are often wrong. Can you tell me more?
A: In the Canadian study, researchers found the units weren’t accurate within five mmHg of blood pressure about 70% of the time, and the devices were off the mark by at least 10 mmHg about 30% of the time. But it’s also important to realize that the readings in this study were sometimes both too high and too low, so the potential disagreement goes both ways. Just remember that, if there’s disagreement in the measurement, it would be worth getting your device calibrated.
Q: I don’t have high blood pressure, but I frequently monitor mine because it runs in my family. Should I be suspicious of my readings?
A: I don’t think anyone who owns these home devices should be worried. Guidelines suggest we should be doing more of this home blood-pressure measurement, not less.
My personal opinion is that anyone who has hypertension should have a home blood-pressure device and should monitor themselves enough to know if their blood pressure is at goal. Just remember that home blood-pressure monitoring cannot take the place of physician measurements during your checkup.
Q: I’ve heard the term “white-coat syndrome” used to describe a higher blood-pressure reading. Can you explain that to me?
A: In a rushed environment or busy clinical day, the measurement of blood pressure in your doctor’s office is also sometimes just as inaccurate or even worse. I generally tend to believe the home blood pressure measures more, because they are done when the patient is relaxed, at home, and comfortable. The term ‘white-coat syndrome’ refers to the fact that your blood pressure when taken in a clinical setting is higher, above the normal range, as opposed to when it’s taken at home, most likely due to the anxiety some experience when visiting their doctor.
Q: What exactly does my blood pressure tell my doctor? And what is normal?
A: High blood pressure is one of the six big ones to control when it comes to risk factors for heart disease. But it’s not just a heart attack or heart failure that you need to worry about. We often refer to high blood pressure as the silent killer because symptoms don’t usually appear until it’s too late, when undiagnosed blood pressure begins to result in complications. Common complications and their signs and symptoms include aneurysms, kidney disease, cognitive changes, eye damage, peripheral artery disease, and stroke.
A blood pressure reading of 110/70 is ideal, less than 120/80 is normal, and a reading greater than 140/90 is high. If your blood pressure is between these two, more monitoring is reasonable to identify if changes occur and when to initiate therapy. This category is often referred to as pre-hypertension, and people with blood pressure in that range are more likely to progress to full-blown high blood pressure if they don’t do something about it before then.
Q: When should I check my blood pressure?
A: I recommend checking your blood pressure within two hours of waking up. If your blood pressure is controlled at that time of day, it is usually controlled for the rest of the day. As for frequency, check it daily for about two weeks to get a sense of what your average blood pressure is. If well-controlled, then measuring your blood pressure at home about monthly is usually enough. And it’s always important to keep a blood-pressure log to share and compare.
Q: Should I be worried if my doctor diagnoses me with high blood pressure?
A: The good news is that high blood pressure is very treatable with well-tolerated medications. You can also help lower your blood pressure by making several lifestyle changes such as maintaining a healthy body weight and eating a healthy diet low in sodium, as well as engaging in moderate physical exercise for about 30 minutes daily.
Dr. Quinn Pack is a preventive cardiologist in the Heart & Vascular Program at Baystate Medical Center.