A study that examined the spines of people without back pain is casting serious doubt on the methods used to diagnose and treat people whose backs ache.

The study led by Dr. Michael N. Brant-Zawadzki, a radiologist at Hoag Memorial Hospital in Newport Beach, Calif., used magnetic resonance imaging, MRI., to examine the spines of 98 men and women who had no back pain. The researchers found that nearly two-thirds of the subjects had spinal abnormalities, including bulging or protruding disks, herniated disks and degenerated disks. A third had more than one abnormal disk.

The investigators concluded that in many cases it may be sheer coincidence - not cause and effect - when a person with back pain is found to have an abnormal disk. Nevertheless, experts say, the use of MRI, a popular and sensitive imaging method, often leads to unnecessary surgery.

The study was published in The New England Journal of Medicine, accompanied by an editorial by Dr. Richard Deyo, a specialist in internal medicine at the University of Washington in Seattle. "I hope this study is very influential," said Dr. Deyo, whose research focuses on the outcome of treatment for back pain. "Many doctors routinely use MRI's to diagnose back pain," he said. "Misuse of the results of this imaging method is a bigger problem than physicians or patients realize," he said, adding, "The opportunity to be misled is substantial." Dr. Robert Boyd, an orthopedic surgeon at Massachusetts General Hospital in Boston, said researchers showed that many patients without back pain had abnormalities.

Cost Put at $8 Billion

The new study follows others that showed that no matter what methods doctors used to diagnose back pain, there seemed to be no correlation between MRI abnormalities and a large percentage of people with NO back pain.

"Most back pain is never explained," Dr. Boyd said. But he added that most back pain also went away by itself. "If you take 100 people with new back pain and look at them again three months later, 98 of them will be better," he said. "Anything you do to treat them in those three months will be given credit for healing. Providers begin to believe that the treatment they are providing is the reason for the improvement. Patients believe it, too."

Back pain is second only to the common cold as a reason Americans visit their doctors, Dr. Brant-Zawadzki said. As many as 80 percent of the nation's citizens complain of aching backs at some time in their lives, and nearly a third have back pain at any given moment. The annual cost of medical care for people with back pain is more than $8 billion, he said.

Since MRI scans cost about $2,000 each, their overuse and misuse wastes health care dollars, medical researchers said. "Too often, people try to use the MRI to make a diagnosis," said Dr. John Froymeyer, director of the McClure Musculoskeletal Research Center at the University of Vermont. "It misleads you often enough that you perform unnecessary surgery, and the results are not very good."

Temptation for Doctors

Moreover, Dr. Froymeyer said Americans have almost 10 times more spinal disc operations than people in other Western countries, far more neurosurgeons and orthopedic surgeons, and many times more MRI machines. For example, he said, there are more MRI machines in Boston than in all of Canada. Dr. Boyd attributed overuse of MRI's to "insecurity, threat of lawsuits, inexperience and the potential for economic gain."

Dr. Brant-Zawadzki said: "Certain physicians like to be able to explain to their patients why they're feeling what they're feeling. The temptation is there for doctors who are not sophisticated to be glib about disc abnormalities and patients' symptoms. "In all the years that doctors have been operating on people with back pain, there has been only one randomized controlled clinical trial comparing surgery to conservative treatment like bed rest and exercises, and that was done 20 years ago in Norway. The study included patients with ruptured disks, Dr. Boyd said, and found that a year after the patients' problems were diagnosed, about 80 percent of those who had surgery were better, compared with half of those who did not have surgery. But four years after the study began, the patients who had had surgery were no different from those who were treated without it - about 80 percent of both groups were better.

"Surgery doesn't put new backs in and it doesn't give better long-term results, "Dr. Boyd said. "It is indicated when pain doesn't respond to conservative treatment and is clearly associated with nerve root compression. Then the results of surgery are excellent. Instead of waiting a year or two or three to get better, you can wake up from the operation and that bad leg pain is gone or much better." But he added that only about 5 percent of people with back pain fell into this category.

Test Often Unnecessary

Dr. Froymeyer said M.R.I, scans could not even tell a surgeon where to operate. "These tests are to confirm clinical judgment, not to make a diagnosis," he said. "People need to understand that most of the time these tests do not need to be done unless there is some definite reason."

Asked if more MRI's are done than are needed. Dr. Boyd said his answer was "an unqualified yes." He said that although he would recommend MRI scans for very few of the patients referred to him, "I don't see many patients who haven't already had two or three MRI's. He added: "Some physicians won't even see a patient without getting an MRI. They will say, 'Get an MRI., send it to me, and I'll tell you if I want to see you."'

A back problem and an abnormality of a disk are often a matter of chance.

References

1. Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994;331:69-73.