Antidepressants Unproven As Treatment For Low Back Pain

Antidepressants might be worthless for treating low back pain, suggests a new review that found no evidence to support using the drugs in this way. Yet, up to 23 percent of U.S. physicians report prescribing antidepressants to patients with low back pain.

"The prescription of antidepressants as a treatment for back pain remains controversial," Donna Urquhart, Ph.D., research fellow at Monash University in Melbourne, Australia, and lead review author.

The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

Physicians commonly prescribe antidepressants for patients with low back pain to provide pain relief, aid in sleep and treat coexisting depression.

Roger Chou, M.D., is the director of the American Pain Society's Clinical Practice Guideline Program, which recently published new practice guidelines for the management of low back pain in conjunction with the American College of Physicians.

"Antidepressants are considered second- or third-line agents in the treatment of low back pain," Chou said. "It's very common to be depressed with chronic pain, so that may be when clinicians are inclined to try a medication for both the chronic pain and the depression." Chou, an associate professor at the Oregon Health and Science University, was not involved with the Cochrane review.

For the review, Urquhart and colleagues analyzed 10 published studies that compared antidepressants to placebos in patients with low back pain. The studies included patients with problems such as ruptured discs, slipped vertebrae and pain due to pinched nerves. Four studies included both depressed and non-depressed patients. In two studies, it was not clear whether patients were depressed. One study targeted patients with low back pain and concurrent depression.

In most studies, patients could continue taking other pain medications such as aspirin and non-steroidal anti-inflammatory drugs (NSAIDs).

Five studies reported no differences in pain between patients receiving antidepressants and those receiving a placebo; however, two studies reported less pain in patients receiving antidepressants. Seven studies reported no differences in depression in patients receiving antidepressants who also had low back pain compared to patients receiving placebo.

"The review found no convincing evidence that antidepressants relieve back pain or depression more effectively than placebo," Urquhart said. Nor did researchers find any difference in patients' ability to function, whether receiving antidepressants or placebo.

The majority of the studies looked at tricyclic antidepressants such as amitriptyline, nortriptyline and clomipramine. Two studies evaluated the effectiveness of paroxetine (Paxil is one brand), a selective serotonin reuptake inhibitor (SSRI).

In addition, two studies evaluated the 'atypical' antidepressants, bupropion (Wellbutrin) and trazodone.

After analyzing the findings of these studies, the researchers concluded, "Both tricyclics and SSRIs were no more effective than placebo in reducing pain."

Chou, of the American Pain Society, said that three previously conducted systematic reviews have found that some antidepressants are modestly effective in the treatment of low back pain. "It's striking that the Cochrane review came to different conclusions than the older reviews." This might have occurred because the review measured improvement in symptoms using different criteria than the previous reviews, he added.

"It's been pretty well shown that tricyclic antidepressants and antidepressants that modify norepinephrine uptake, such as duloxetine (Cymbalta) and venlafaxine (Effexor), do have an effect on reducing chronic pain," he said.

Urquhart cautioned that patients with significant depression should not avoid antidepressants based on the findings of this review, because there is evidence that antidepressants can help patients with clinical depression.

"However, existing studies do not provide adequate evidence for or against the use of antidepressants in low back pain and further research is needed," she said. "In the meantime, antidepressants should be regarded as an unproven treatment for nonspecific low back pain."

Chou said that reviews like this are important for patients so they can learn about what options are available and which ones are effective. "There are so many treatments and it's very confusing for patients and clinicians alike."