Researchers from seven universities and the World Hypertension League analyzed more than 970 home blood pressure devices being sold by nearly 60 online retailers. Almost 95 percent of the devices hadn’t been validated for accuracy. “High blood pressure is the single largest risk factor for cardiovascular disease worldwide, so it’s really important to measure blood pressure accurately,” says James Sharman, PhD, the deputy director of the Menzies Institute for Medical Research at the University of Tasmania, who led the study. Dr. Sharman and his team also found that cost was the most significant barrier that may sway shoppers away from purchasing home blood pressure devices that have been validated. On average, validated devices cost roughly US$20 more than unvalidated devices, the study found. “Validation is expensive, so companies that want to make an easy profit don’t do it,” says Bruce Alpert, MD, the former chief of cardiology at St. Jude Children’s Research Hospital in Memphis, Tennessee, who was heavily involved in drafting internationally recognized guidelines for blood pressure device validation. Even unvalidated upper arm cuffs were pricier than the average wrist cuff. According to Sharman, this is important because upper arm cuff devices are generally considered the most accurate type of home device.
FDA Approval Is Different From Validation
Willie E. Lawrence, MD, an American Heart Association (AHA) expert and the chief of cardiology at the Midwest Heart and Vascular Specialist Research Medical Center in Kansas City, Missouri, worries that consumers may associate the higher price tag with a device that has “more bells and whistles” than accuracy. “The consumer makes the assumption that if they go to a store or pharmacy, that any monitor they pick will be accurate,” says Dr. Lawrence. Discrepancies between medical device approval and medical device validation are likely a source of confusion for patients using devices at home. Regulatory authorities such as the U.S. Food and Drug Administration (FDA) and the Therapeutic Goods Administration (TGA) in Australia screen medical devices for safety before the products can be legally sold in either country. “The level of rigor around accuracy testing is relatively weak, which means that a blood pressure device can be legally sold, yet perform poorly in terms of accuracy,” says Sharman. In short, companies must prove that they have tested their device and that it does not directly cause harm, but not necessarily that it provides consistently accurate readings. Guidelines for validation are put forth by organizations — rather than regulatory authorities — including the Advancement of Medical Instrumentation (AAMI), the British and Irish Hypertension Society, and the European Society of Hypertension (ESH). Most, but not all, of these organizations recognize the International Organization for Standardization (ISO) process for validation, which requires rigorous accuracy testing by a third party that does not have ties to any manufacturer. Still, a device that is validated in one country may not be in another. “Even if your device is validated, you should always check it against your doctor’s,” says Dr. Alpert.
Accuracy Is Vital
The AHA recommends that anyone with high blood pressure monitor their blood pressure at home to help their doctors determine whether or not treatments are working. “The numbers that these devices provide allow healthcare providers to make critical judgments regarding whether a patient needs a medication, and if so, how much to give. Good medical decisions simply can’t be made using potentially bad data,” says John Bisognano, MD, PhD, the director of the comprehensive hypertension center at the University of Rochester Medical Center in New York. Lawrence says that home devices are also useful tools that can alert at-risk patients of abnormal blood pressure readings before their condition escalates to hypotension or hypertension. “Inaccurate readings could give people a false sense of security,” he says, noting that doctors should have access to a list of validated home blood pressure devices that can be used to help patients pick the right one. You can also check a number of online databases. Sharman was part of a team that put together a guide for using the Stride BP and Medaval registries, where online shoppers can quickly check to see if the device they are considering purchasing has been validated. The guide also provides a link to registries from six countries, including one for the United States, which is set to launch this year. As a baseline, patients “should almost never select a wrist monitor,” says Dr. Bisognano.
