NSAIDs, Acetaminophen Equivalent in Relieving Low Back Pain

By Michael Smith
ROTTERDAM, The Netherlands, Jan. 23 -- For lower back pain, the old standby acetaminophen appears to be as effective for pain relief as nonsteroidal anti-inflammatory drugs (NSAIDs), researchers here said.
A meta-analysis of 65 studies of NSAIDS for lower back pain, with or without sciatica, showed the drugs are more effective than placebo but roughly equivalent to acetaminophen, according to a systematic review published in the first 2008 issue of The Cochrane Library.
But NSAIDs have significantly more side effects -- mainly gastrointestinal -- than acetaminophen, with a relative risk of 1.76 (with a 95% confidence interval from 1.12 to 2.76), the researchers found.
The findings support guidelines that suggest NSAIDs be used only after acetaminophen (also known in Europe as paracetamol) has been tried, "since there are fewer side effects with paracetamol," said lead author Pepijn Roelofs, a doctoral student at Erasmus University in Rotterdam, Holland, and colleagues.
The report is an undated version of a review first published in 2002. It includes 15 new studies, the researchers said. Of the 65 evaluated studies, which enrolled 11,237 patients, 28 (or 42%) were considered high quality.
The 65 studies compared NSAIDs to placebo, acetaminophen, muscle relaxants, and other drugs, non-drug treatments, and other NSAIDs, the researchers said.
They looked at 11 studies comparing NSAIDS to placebo in acute low back pain and four in chronic pain.
For acute pain, the studies were heterogeneous, but there was enough information to conclude that NSAIDs were more effective than placebo, with a pooled relative risk for global improvement after one week of 1.19, with a 95% confidence interval from 1.07 to 1.33.
The effect sizes seen in the individual studies were also small, the researchers noted.
On the other hand, there was no significant difference if the patients were suffering from sciatica.
Side effects were more common in patients getting NSAIDs, with a pooled relative risk of 1.35 (with a 95% confidence interval from 1.09 to 1.68).
For chronic pain, NSAIDs also significantly reduced pain (P<0.00001), but had significantly more side effects (pooled relative risk of 1.24, with a 95% confidence interval from 1.07 to 1.43).
Only seven studies compared one or more types of NSAIDs with acetaminophen, the researchers found and they provide "moderate evidence" that the two forms of medication are equivalent in reducing acute low back pain, the researchers said.
But, they said, there's "limited evidence" -- a single study -- showing NSAIDs to be more effective in treating chronic pain.
The analysis also found:
"Moderate evidence" that NSAIDs are no more effective than other drugs for acute low back pain.
"Strong evidence" that various types of NSAIDs, including the controversial cyclooxygenase-2 inhibitors (COX-2), are equally effective for acute low back pain.
The COX-2 NSAIDs, in these studies, had significantly fewer side effects than traditional NSAIDs. The pooled relative risk was 0.83, with a 95% confidence interval from 0.70 to 0.99.
The researchers noted that the COX-2 inhibitors have been enveloped with controversy over long-term cardiovascular side effects.
"It might well be," they argued, "that in the majority of patients with low back pain, the intake is of short duration and might not reach the level associated with increased cardiovascular risks."
The benefit of the medications "varies from individual to individual," said Jon Levine, M.D., of the University of California San Francisco, who was not affiliated with the review.
"If one NSAID does not work, you can try another," he said in a statement. "This is often a very empirical situation. If it takes care of the pain, wouldn't you take it?"
The study was supported by the Dutch Health Insurance Board.
The researchers did not report any potential financial conflicts.
Primary source: Cochrane Database of Systematic ReviewsSource reference:Roelofs PDDM, et al "Non-steroidal anti-inflammatory drugs for low back pain" Cochrane Database of Systematic Reviews 2008; Issue 1: DOI: 10.1002/14651858.CD000396.pub3.