You don’t need a prescription to buy an at-home blood-pressure monitor. But before spending $40 to $150, you should talk with your physician.

More doctors might recommend home tests now based on advice from the American Heart Association and other medical groups.

People with hypertension or suspected high blood pressure should routinely self-monitor, according to an AHA statement issued in May. Seniors, whose blood pressure can vary, are good candidates for at-home tests. These tests can also be useful for people who experience “white-coat hypertension,” a spike in blood pressure when they are tested in a doctor’s office or hospital.

“Taking an active role by home monitoring empowers patients by giving them a sense of control that motivates them to partner with their doctors and stick with their treatment regimen,“ says Jennifer Mieres, M.D., an AHA spokeswoman and director of nuclear cardiology at the New York University School of Medicine.

More patients need to monitor themselves at home, and it’s important that they choose the best blood-pressure monitors for their needs, including devices that will provide accurate readings. When we tested the top-selling home monitors, we obtained approximately 6,000 readings from 57 men and women.

We compared the results of the home monitors with those obtained by pairs of trained medical technicians who used a mercury sphygmomanometer, the standard instrument for recording accurate blood-pressure readings. In our analysis, only models with readings that met U.S. and international standards were judged excellent for accuracy.