SAUSALITO, CA (ASRN.ORG) -- It’s such a routine thing: A nurse wraps the cuff around your elderly relative’s arm, squeezes the bulb, listens with a stethoscope and says: “120 over 60. Very good.” Smiles all around (this was my 89-year-old father’s latest reading), because everyone knows that high blood pressure is a risky proposition.

Or is it? Reading a study and an editorial while waiting for him in the outer office, I was startled to learn that in the very elderly — those over 85, say — high blood pressure may indicate better health while lower numbers could mean trouble ahead. For a layperson, this was such a through-the-looking-glass moment that I called Dr. James Goodwin, a geriatrician at the University of Texas Medical Branch in Galveston who wrote the editorial, and asked, in essence, does everyone know this but me?

“These are very well-kept secrets,” he said. “That high blood pressure in those over 85 predicts longer survival would probably be news to 95 percent of practicing physicians.” Which was not entirely reassuring.

Dr. Goodwin has been writing for years about the way blood pressure readings and other indicators of health, like weight and cholesterol, take on different meanings in advanced age. What sparked this latest discussion was a new study that examined whether walking speed might identify which older people are more at risk from high blood pressure, as hypertension is commonly known.

An Oregon State University epidemiologist, Michelle Odden, and a team at the University of California, San Francisco, reviewed data from the National Health and Nutrition Examination Survey, following 2,340 people over age 65 for an average of five years. The researchers divided the participants into categories based on the pace at which they walked a 20-foot corridor. Among fast walkers, who averaged a pace of 1.8 miles per hour or better, those with elevated blood pressure had a 35 percent higher risk of dying — the same risk seen in younger adults. But in slower walkers, hypertension did not increase mortality.

And in a small group of participants who didn’t complete the walk, those with high blood pressure had a 60 percent lower risk of death.

If these were the only data suggesting that hypertension’s effects begin to reverse in old age, we could shrug them off. In this study, those who didn’t or couldn’t walk 20 feet offered a variety of reasons: many had physical limitations or felt unsafe, but “some just showed up late for their appointments,” Dr. Odden acknowledged. Hard to draw conclusions from that.

But this isn’t the first study showing an inverse association — hypertension equals longer life — in the very old. “It expands on a fairly substantial amount of research on the relationship between blood pressure and survival,” Dr. Goodwin said. What doctors should do about hypertension in the very elderly – treat it or leave it alone? – has generated controversy for decades, particularly since clinical drug trials often exclude the elderly, leaving doctors with scant evidence to go on.

The medical guidelines for treating hypertension, set by a Joint National Committee in 2003 (and about to be updated) established a goal of 140/90; the systolic reading, the first of the two numbers, is the more important measure in people over age 50. The guidelines recommend medication for people who have higher blood pressure (as more than two-thirds of those over age 65 do) because of the well-established risk of heart attack and stroke. The recommendations don’t differ for the very old, but perhaps they should.

“The paradigm in medicine is, high blood pressure is bad, treating it is good,” Dr. Odden said. “We’re saying, maybe we need to look more closely at the guidelines and tailor them more to older adults.” Her study shows that “it’s not just age, it’s your physiology, your functional status, frailty” that matters.

What do we do with this? For younger people, the decisions are clear-cut: Reducing high blood pressure is a priority, and our increasing success at it represents a major public health victory, one reason we’ve become an aging nation.

In the very old, however, lower readings could mean good health, or they might also indicate that a patient’s heart isn’t pumping efficiently, while higher readings may mean robustness. “It can make you quite a bit less aggressive in treatment,” Dr. Goodwin said, especially since hypertension drugs can cause falls and dizziness.

Dr. Ken Covinsky, a geriatrician at the University of California, San Francisco, and senior author of the new study, said he’d probably recommend treatment for an 80-year-old tennis player with high blood pressure, but would be less worried about a frail 80-year-old with a systolic reading of 160, especially if she was already prone to falling.

“Do we really want to give her a ninth medication?” he asked. “I’d feel a little queasy about that.”

It’s a conversation worth having with a doctor, though hypertension treatment has become so reflexive that it could be a tough discussion. “Few physicians are aware of these findings, and they’re going to be suspicious,” Dr. Goodwin said.

But give it a try anyway, he said: “We have to bring the complexity of decision making in the elderly into the light of day.”

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