One of the case studies I use in How We Decide when discussing the dangers of information overload concerns the diagnosis of back pain. Before the introduction of MRI’s in the late 1980s, doctors were forced to rely on X-rays when diagnosing back pain. X-rays provide doctors with a limited amount of information, since they only reveal the bones and spinal column. As a result, back pain remained a mostly mysterious phenomenon, and most patients were prescribed bed rest. Nevertheless, this simple treatment plan was still extremely effective. Even when nothing was done to the lower back, about 90 percent of patients with back pain managed to get better within seven weeks.
However, that all changed with the introduction of MRI. Within a few years, the MRI machine became a crucial medical tool. It allowed doctors to look, for the first time, at stunningly accurate images of the interior body. The medical profession hoped that the use of MRI would revolutionize the treatment of lower back pain. Since doctors could finally image the spine and surrounding soft tissue in detail, they should be able to offer precise diagnoses, locating the aggravated nerves and structural problems that caused the pain in the first place. This, in turn, would lead to better medical care.
Unfortunately, MRI’s haven’t solved the problem of back pain. In fact, the new technology has probably made the problem worse. Here’s the Well blog on the NY Times, summarizing a new study published in The Lancet:
Researchers from Oregon Health and Science University in Portland reviewed six clinical trials comprised of nearly 2,000 patients with lower back pain. They found that back pain patients who underwent scans didn’t get better any faster or have less pain, depression or anxiety than patients who weren’t scanned. More important, the data suggested that patients who get scanned for back pain may end up with more pain than those who are left alone, according to the report published this week in the medical journal Lancet.
Why do MRI’s often lead to worse medical outcomes? The machine simply sees too much. Doctors are overwhelmed with information, and struggle to distinguish the significant from the irrelevant. Take, for example, spinal disc abnormalities. While X-rays can only reveal tumors or problems with the vertebrae, MRI’s can image spinal discs⎯the supple buffers between the vertebrae⎯in meticulous detail. After the imaging machines were first introduced, the diagnosis of various disc abnormalities began to skyrocket. The MRI pictures certainly looked bleak: people with pain seemed to have seriously degenerated discs, which everyone assumed caused inflammation of the local nerves. Doctors began administering epidurals to quiet the pain, and, if the pain still persisted, would surgically remove the necessary disc tissue.
The vivid images, however, were misleading. A 1994 study published in The New England Journal of Medicine imaged the spinal regions of ninety-eight people with no back pain or any back related problems. The pictures were then sent to doctors who didn’t know that the patients weren’t in pain. The end result was shocking: two-thirds of normal patients exhibited “serious problems” like bulging, protruding or herniated discs. In 38 percent of these patients, the MRI revealed multiple damaged discs. Nearly 90 percent of these patients exhibited some form of “disc degeneration”. These structural abnormalities are often used to justify surgery and yet nobody would advocate surgery for people without pain. The study concluded that, in most cases, “The discovery by MRI of bulges or protrusions in people with low back pain may be coincidental.”
In other words, seeing everything made it harder for the doctors to know what they should be looking at. The very advantage of MRI⎯its ability to detect tiny “defects” in tissue⎯turned out to be a liability, since many of the defects were actually a normal part of the aging process. This is the danger of too much information: it can actually interfere with our understanding. We confuse correlation with causation, and make theories out of coincidences. We latch onto medical explanations, even when the explanations don’t make very much sense.
As I note in the book, medical experts are now encouraging doctors not to order MRIs when diagnosing back pain. A recent report in The New England Journal of Medicine concluded that MRIs should only be used to image the back under specific clinical circumstances, when doctors are examining “patients for whom there is a strong clinical suggestion of underlying infection, cancer, or persistent neurologic deficit.” In the latest clinical guidelines issued by the American College of Physicians and the American Pain Society, doctors were “strongly recommended…not to obtain imaging or other diagnostic tests in patients with nonspecific low back pain.” In too many cases, the expensive tests proved worse than useless. All of the extra detail just got in the way. The doctors performed better with less information