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Older adults may be getting too many bone mineral density tests, study suggests

Older people at risk for osteoporosis are sometimes recommended to get a bone mineral density (BMD) screening test every two years to see if fractures may occur in the near future. But, a new study suggests screening that often may not be necessary.

Researchers looked at a group of adults who were an average age of 75, and found a second bone mineral density test taken as much as four years after the first did not offer any meaningful information on fracture risk.

They called for more studies to determine the optimal time-frame between screening to avoid putting patients through unnecessary, costly medical tests.

"Although the appropriate time interval between BMD screening tests remains unknown, the current clinical practice of repeating a BMD test every 2 years to improve fracture risk stratification may not be necessary in all adults 75 years or older untreated for osteoporosis," concluded the researchers, led by Dr. Sarah Berry, a geriatric researchers at the Harvard-affiliated Hebrew SeniorLife Institute for Aging Research in Boston.

Berry's study was published Sept. 24 in JAMA.

Bone density testing utilizes low-dose x-rays in an imaging scan called DEXA. There are two types of tests, the National Institutes of Health notes: Central DEXA, in which a scanner passes over the lower spine and hip when the patient lays on a table, and Peripheral DEXA, which use smaller machines that can measure bone density in areas like the wrist, legs and feet.

The tests can diagnose osteoporosis, a disease caused by bone breaking down due to aging, and if people are at risk for fractures. Young people produce more new bone than their body breaks down, according to the Mayo Clinic, but most people reach peak bone mass by their early 20s. That means over time mass is lost, which can lead to serious complications like spinal or hip fractures that can result in disability or death.

Medicare reimburses older individuals for BMD screening every two years, and the study's authors note about 22 percent of those who get screened get a repeat bone test within three years.

"Given the priority of reducing health care costs while improving quality of care, it is important to determine whether repeat BMD screening is useful," the researchers wrote.

They compiled data from 310 men and nearly 500 women enrolled in a long-running osteoporosis study of adults recruited between 1987 and 1999 who underwent BMD screening every four years. Subjects were tracked through about 12 years after they received their second BMD test.

Only 113 people developed one or more major fractures, and the second test provided little to no additional predictive value for their injuries.

"Of those who went on to experience a hip fracture, repeating a bone-density test improved our ability to classify a person at higher risk by about 4 percent," Berry said to HealthDay.

A 2012 study in the New England Journal of Medicine found if an initial scan shows no problems,some older women can even wait 15 years to have another BMD test.

Dr. Chad Deal, director of the Center for Osteoporosis and Metabolic Bone Diseases at the Cleveland Clinic, emphasized to that many individuals do indeed need frequent BMD tests, and that should not be lost in the study's conclusion.

He noted that this study had several limitations, some of which the authors themselves acknowledged. More than 90 percent of patients were tested on two different machines, when a cardinal rule is to use the same machine, he said. Parents' fracture history, or whether these people were taking medications -- like bisphosphonate drugs prescribed for bone loss -- were also not accounted for, said Deal, who was not involved in the study.

The study did not also account for if the women were entering menopause. Up to 20 percent of women who are entering menopause, or are perimenopausal, can experience rapid bone loss to the point of 5 percent loss in mass every year for six years, he added.

"The only way to detect those is to repeat a bone density," he said.

Further, the most rapid bone loss requiring more frequent DEXA scans occurs in the spine, he said, while the study mainly focused on the hip as a separate outcome.

The takeaway, said Deal, should be that some groups will benefit from more frequent screening including menopausal women, smokers, alcohol users, women who took aromatase inhibitors to treat breast cancer and anyone taking a medication for bone loss. They all may at greater fracture risk and benefit from more frequent screening, he said.

The takeaway should not be that all individuals should put off DEXA screening for four years or more.

"That would be a really mistaken message," said Deal.

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