Psychological factors predict back pain

May 28, 2004

May 28, 2004

Stanford, CA - Psychological distress is a more reliable predictor of lower back pain than imaging or diagnostic disk injection, researchers from Stanford University have shown. This could have implications for the treatment of back pain, they note.

Orthopedic surgeon Dr Eugene Carragee (Stanford University, CA) and colleagues report their findings in the May 15, 2004 issue of Spine [ 1 ].

Carragee et al explain that it has been thought by many clinicians that "provocative discography"—which involves an injection into the lumbar disk to see whether it elicits pain—might help predict who will go on to develop lower back pain in subjects who are currently asymptomatic but may have had other spinal problems or suffer pain.

The bottom line is that [discography] didn't predict who would go on to develop back pain.

"It was thought that discography could separate the wheat from the chaff," Carragee says, "but the bottom line is that it didn't predict who would go on to develop back pain." Instead, the researchers showed that psychological factors more accurately predicted who would develop lower back pain than the 2 diagnostic techniques.


Longest follow-up of high-risk, asymptomatic group

Carragee and his team examined 46 discography subjects and 49 control individuals annually over the 4-year study period. Some of them had undergone cervical surgery or had been diagnosed with chronic pain syndrome, but none had lower back pain at the start of the study. They studied their subjects' spines using both disk injection and magnetic resonance imaging (MRI) and also performed psychological evaluations.

"Nobody had ever followed a high-risk, asymptomatic group with discography or MRI for such a long period," says Carragee.

The researchers found that patients with poor coping skills—as measured by psychological testing—or with chronic pain were nearly 3 times more likely to develop back pain compared with those with neither (p=0.01). A history of disputed workers' compensation claims also predicted future back pain, as did medication usage.

But a painful disk injection, independent of psychological profile, did not predict lower back pain. And while a crack in the disk or a "high-intensity zone" seen on MRI was weakly associated with back pain, this was not statistically significant (p=0.09).

"The structural problems were really overwhelmed by the psychosocial factors," Carragee notes.


How to best identify those who will benefit from surgery

Some insurance companies and state workers' compensation funds are already balking at paying for surgery to treat nonspecific back pain associated with psychosocial problems, Carragee says. Only a quarter of the 300 000 spinal-fusion operations that occur each year are done for obvious reasons, such as tumors, infections, or deformities, and just a fraction of the rest—those with pain and ordinary age-related degeneration—have good results from the surgery.

Although this study confirms the strong association previously noted between chronic pain and psychological distress as a predictor of future lower back pain troubles, "the data do not illuminate how this relates to positive disk injections in experimental or clinical settings," the authors note.

"The question is, can we better identify groups that have a greater chance of being helped by surgery?" Carragee wonders. It may be more appropriate to treat patients by helping them cope with the pain and strengthening their backs, he concludes.

Source

  1. Carragee EJ, Barcohana B, Alamin T, van den Haak E. Prospective controlled study of the development of lower back pain in previously asymptomatic subjects undergoing experimental discography. Spine 2004 May 15; 29(10):1112-7

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