Measuring your blood pressure at home is an easy way to keep track of it, but readings from at-home devices may be wrong nearly 70 percent of the time, according to new research.

Scientists from the University of Alberta, who conducted the research, note that these inaccuracies can lead to serious problems for people who depend on the readings to make decisions.

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“High blood pressure is the number one cause of death and disability in the world,” lead study author Jennifer Ringrose said in a statement. “Monitoring for and treating hypertension can decrease the consequences of this disease. We need to make sure that home blood pressure readings are accurate.”

In a small study, published in the American Journal of Hypertension, Ringrose and her colleagues compared 85 patients' at-home monitor readings with a gold standard method. The findings revealed most of the at-home devices were off by five mmHg, or millimeters of mercury, 69 percent of the time. About 30 percent of the time, the devices gave readings that were wrong by at least 10 mmHg (the units used to measure blood pressure).

Men were more likely than women to have inaccurate results, which may be due to a number of different factors, the researchers point out.

“Arm shape, arm size, the stiffness and age of blood vessels and the type of blood pressure cuff are not always taken into account when a blood pressure machine is designed and validated,” study co-author Raj Padwal said. “Individual differences, such as the size, age and medical background of the person using the blood pressure monitor are also contributing factors.”

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Because tests may not always be accurate, the authors recommend comparing at-home measurements with ones taken by a healthcare professional. Multiple readings can provide a better understanding of your current health status.

Hypertension, commonly known as high blood pressure, is a common but serious condition. If you don’t control it, it can lead to many complications: heart attack, stroke, aneurysm, heart failure, impaired kidney function, vision loss, metabolic syndrome, and memory problems, according to Mayo Clinic.

Those with high blood pressure should take at-home readings; however, it is not a substitute for professional care. To make the most of your self-measured readings, here’s some tips from the American Heart Association: sit still; don’t smoke, drink caffeine or exercise within 30 minutes of taking a reading; sit up straight in a chair, rather than sofa; have your feet flat on the floor; measure at the same time every day; take multiple readings and record the results.

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