(HealthDay News) — A new small study raises more questions about the accuracy of home blood pressure monitoring devices. The research is scheduled to be presented at the American Society of Nephrology’s Kidney Week 2014, held from November 11–16 in Philadelphia.
Swapnil Hiremath, MD, of The Ottawa Hospital and University of Ottawa in Canada, and colleagues looked at data from 210 patients – 60% men, with an average age of 67 – who brought their blood pressure monitors to the doctor’s office. “Our nurse, an RN, would measure blood pressure in both arms using the office blood pressure machine,” Hiremath told HealthDay. “Once it was confirmed that there was no difference between arms, measurements were taken in both arms simultaneously – one with the home machine, one with the office machine. Since the data we report is from measurements taken by the RN, this is not a case of patient error.” The office machine was considered to be accurate.
The researchers found that, on average, the systolic and diastolic blood pressure readings were only a few points off in the home devices. Between 30–32% of the time, the blood pressure readings were off by 5mmHg with the home devices. But the readings were off by more than 10mmHg – a difference that could be significant – between 8–9% of the time.
How much might the differences matter? It’s hard to say, Hiremath said. In some cases, an inaccurate reading might not result in a different treatment compared to an accurate reading. A reading of, say, “155 vs. 166 will still often result in the same decision,” he said. But it’s also possible that a small difference could mislead a physician and result in a different kind of decision, he added.