Despite the growing popularity of steroid injections to treat various kinds of back pain in recent years, a new review of past research finds the shots do little to alleviate sciatica, a common condition that causes leg and back pain.

Analyzing results from nearly two dozen clinical trials on thousands of patients, Australian researchers found that epidural injections (into the spine) of corticosteroids had no long- or short-term effect on sciatica back pain, and such a small short-term effect on leg pain it would make no difference to the patient.

"I think it's pretty clear that this treatment is not good to do," said Chris Maher, of The George Institute for Global Health in Sydney, Australia, who worked on the study.

Nonetheless, the use of epidural steroid injections to treat back pain of all sorts among Medicare patients nearly doubled from 741,000 in 2000 to about 1,438,000 in 2004, according to the researchers.

In the U.S., the cost of one shot can be several hundred dollars.

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And a tainted supply of one of the steroids included in the trials under analysis - methylprednisolone - recently caused a nationwide outbreak of fungal meningitis that infected 400 people and led to 31 deaths, according to the Centers for Disease Control and Prevention.

For sciatica, which is thought to be caused by nerve damage, past studies have already questioned the effectiveness of spinal steroid shots.

In April, for instance, a study of 81 people found that whether they received steroids or a placebo for sciatica, their condition ended up improving about the same amount.

Maher and his colleagues set out to see whether past studies supported the use of epidural corticosteroid injections to help manage sciatica, and collected results from "gold standard" randomized controlled trials.

Overall, 23 trials were included in the final analysis, which represented about 2,300 patients, whose pain was ranked on a scale from zero to 100 - with higher scores representing worse pain.

For the back pain component of sciatica, the researchers found that the injections didn't seem to make a difference over short or long periods of time.

When it came to leg pain, there was no difference a year or so after the injection, but there was a statistically significant six-point drop in pain scores over the short term - about 2 weeks to 3 months.

But that, according to Maher, is not enough to mean anything to a doctor or patient.

"You can appreciate that six points on a hundred-point scale is a tiny difference, and in our view that is probably not clinically important," he said.

'Question is closed'

"We really think the question is closed," said Maher. "So in terms of our research agenda, we're moving on to other treatments for sciatica."

Maher told Reuters Health that, instead of steroid injections, people suffering with sciatica should consult their doctor, but other options include simple pain relievers, such as acetaminophen, drugs that treat pain by working throughout a person's nervous system and, as a last resort, surgery.

Not everyone agrees that steroid injections should be excluded from the hierarchy of treatments for sciatica.

"In general, I think we've learned over the years that the epidural injections are turning out to be less and less successful… but there are times when they should be considered," said Dr. Kirkham B. Wood, chief of the orthopedic spine service at Boston's Massachusetts General Hospital.

He told Reuters Health that he believes an injection should be considered, for example, in someone with sciatica resulting from a relatively recent herniated disc, "who time and medication has not helped."

Wood does believe, however, that the injections are overused, and said there was a time when the injections were the go-to treatment for simple back pain.

"I think the pendulum is certainly swinging away from their broad use," he said.

The meningitis outbreak in the U.S. will also likely dampen enthusiasm for the shots, researchers acknowledged.

"If this was a treatment that worked, then you'd have to weigh the benefits and the harm," Maher said, but it doesn't work (for sciatica), he emphasized.

Maher and his team, who published their results in the Annals of Internal Medicine on Monday, hope doctors will pick up on their findings.

But Maher told Reuters Health that it may take some time to change how doctors see the injections.

"It's been around for decades and it will take a while to stop," he said.