Academy Guidelines Lukewarm on Spinal Steroid Injections for Back Pain

ST. PAUL, Minn., March 9 -- Epidural steroid injections for lower back pain with sciatica has been given a tepid endorsement in guidelines published by the American Academy of Neurology.

Such treatment may cause "some improvement" in radicular lumbosacral pain between two and six weeks after the injection, but "the average magnitude of effect is small," said Carmel Armon, M.D., of Tufts in Boston, and colleagues in Neurology.

And the injections did not appear effective for long-term pain relief, for improving physical function, or for delaying surgery, Dr. Armon and colleagues concluded in the March 6 issue of the journal.

However, these conclusions were based on a review of only four studies, and the guideline authors said that much more research must be done to determine the full extent of safety and efficacy of epidural steroid injections for back pain.

Of an initial 37 studies identified in a literature search, only four met the reviewers' strict inclusion criteria, which included not only prospective, randomized, placebo-controlled, double-blind studies but those using clear case definitions and clear standardized outcome measures.

"With regards to the primary question of this review, amelioration of pain, the findings of the four high-quality studies are internally consistent, showing the following efficacy pattern compared with a control group: no efficacy at 24 hours, some efficacy at two to six weeks, no difference or rebound worsening at three months and six months, and no difference at one year," the authors said.

However, even within that two- to six-week window of efficacy, "the average effect difference (advantage of steroids over control treatment) was small, usually falling short of the value proposed as a clinically meaningful average distance-15 mm on the 100 mm visual analogue pain scale," they added.

There were not enough data to determine whether the injections were effective in treating cervical radicular pain, the authors said.

Epidural steroid injections have been used for back pain and sciatica since the 1950s, and their use has been increasing with time despite limited quality data and conflicting evidence, the authors said.

Medicare spent .9 million in 1999 for lumbar epidural steroid injections, and an additional .5 million on lumbar facet or peri-facet joint injections, plus .6 million for cervical or thoracic epidural steroid injections, the authors said.

The review was limited by not only the small number of studies but because it did not compare other treatments for back pain such as spinal cord stimulation or intrathecal narcotics, the authors said.

In addition, "the available studies did not express the magnitude of relief in terms of the percent of patients attaining a clinically meaningful response, and thus did not permit calculation of number of patients needed to treat in order to benefit one patient," they said.

Future studies should more accurately determine the degree and duration of pain relief and the percentage of patients who achieve a clinically meaningful response. These studies should also identify which patients might be good or poor responders, the ideal number of injections and the best intervals between them, and common complications and their frequency, the authors said.