What is high blood pressure? When do you need medication?

The answer was never clear. What is clear is that a lot of people are on medication that may not need it. In February, the Eighth Joint National Committee relaxed the blood pressure goal in adults 60 years and older to 150/90 from 140/90. The result will be that up to 5.8 million U.S. adults will no longer be told they need hypertension medication. That's good for the federal government, which is going to be increasingly concerned about costs as Obamacare is adopted, and it is good for the parts of culture that believe guidelines are created by pharmaceutical companies who control recommendations. It may actually be fine for patients also.

Blood pressure goals were also eased for adults with diabetes and kidney disease.

"Raising the target in older adults is controversial, and not all experts agree with this new recommendation," said Ann Marie Navar-Boggan, a cardiology fellow at Duke University School of Medicine and lead author of a paper in the Journal of the American Medical Association, which coincided with a presentation at the American College of Cardiology meeting in Washington, D.C. "In this study, we wanted to determine the number of adults affected by these changes." 

The researchers used 2005-2010 data from the National Health and Nutrition Examination Survey (NHANES) conducted by the Centers for Disease Control and Prevention. The database included more than 16,000 participants with blood pressure measurements. 

Based on the study sample, the researchers determined that the proportion of U.S. adults considered eligible for hypertension treatment would decrease from 40.6 percent under the old guidelines to 31.7 percent under the new recommendations.

In addition, 13.5 million adults - most of them over the age of 60 - would no longer be classified in a danger zone of poorly controlled blood pressure, and instead would be considered adequately managed. This includes 5.8 million U.S. adults who would no longer need blood pressure pills if the guidelines were rigidly applied.

"The new guidelines do not address whether these adults should still be considered as having hypertension," Navar-Boggan said. "But they would no longer need medication to lower their blood pressure."

According to the study, one in four adults over the age of 60 is currently being treated for high blood pressure and meeting the stricter targets set by previous guidelines.

"These adults would be eligible for less intensive blood pressure medication under the new guidelines, particularly if they were experiencing side effects," Navar-Boggan said. "But many experts fear that increasing blood pressure levels in these adults could be harmful."

"This study reinforces how many Americans with hypertension fall into the treatment 'gray zone' where we don't know how aggressive to treat and where we urgently need to conduct more research" said Eric D. Peterson, M.D., professor of medicine and director of DCRI.

Navar-Boggan said that even under the newer, less stringent guidelines, an estimated 28 million U.S. adults with hypertension still have uncontrolled blood pressure, and over half of them remain untreated.

"Uncontrolled hypertension is a huge missed opportunity for prevention of cardiovascular diseases such as stroke and heart attack," Navar-Boggan said.