Doctors often have a difficult time diagnosing a physical cause for some patients lower back pain, which can be debilitating. A new report suggests that psychological distress may be a better indicator than medical imaging or injections when it comes to predicting who will develop aching backs.

Eugene J. Carragee of Stanford University and his colleagues tracked nearly 100 people over a four-year period to try to determine how effective predictive measures for lower back pain are. At the start of the study, the researchers used magnetic resonance imaging (MRI), which can identify small cracks or tears in cartilage, to examine the spines of 46 volunteers who did not suffer from lower back pain. In addition, the subjects underwent a procedure known as discography, in which a doctor injects fluid into the spine. If the injections cause pain, the theory holds, the patient may later develop back pain even if he doesnt currently suffer from it. Over the course of the study, the volunteers, along with a control group, completed yearly physical and psychological evaluations.

The researchers determined that patients suffering psychological distress were three times more likely to develop back pain than those with better coping skills. "The structural problems were really overwhelmed by the psychosocial factors," Carragee says. Experiencing other types of chronic pain was also linked to developing back pain, but discography results did not successfully predict future back problems, and the association between MRI results and back pain was not statistically significant. The team is now working on a five-year study that examines a more high-risk group of patients who already have common back pain. Notes Carragee: "The question is, Can we better identify groups that have a greater chance of being helped by surgery?" The study results appear in the May 15 issue of the journal Spine.