Acetaminophen. Acupuncture. Massage. Muscle relaxants. Cannabinoids. Opioids. The list of available treatments for low back pain goes on and on. But there’s not good evidence that these treatments actually reduce the pain, according to a new study that summarized the results of hundreds of randomized trials.
Low back pain affects an estimated one in four American adults and is the leading contributor to disability globally. In most diagnosed cases, the pain is considered “nonspecific,” meaning it doesn’t have a clear cause. That’s also partly what makes it so hard to treat.
In the study, published on Tuesday in the journal BMJ Evidence-Based Medicine, researchers reviewed 301 randomized trials that compared 56 noninvasive treatments for low back pain, like medications and exercise, with placebos. They used a statistical method to combine the results of those studies and draw conclusions, a process known as a meta-analysis.
The researchers found that only one treatment — the use of nonsteroidal anti-inflammatory drugs, or NSAIDs, like ibuprofen and aspirin — was effective at reducing short-term, or acute, low back pain. Five other treatments had good enough evidence to be considered effective at reducing chronic low back pain. These were exercise; spinal manipulation, like you might receive from a chiropractor; taping the lower back; antidepressants; and the application of a cream that creates a warming sensation. Even so, the benefit was small.
“The big takeaways from this paper are that low back pain is exceptionally difficult to treat,” said Steve Davidson, the associate director of the N.Y.U. Pain Research Center, who was not involved in the study. “There are a few treatments that they found that were effective, but those that were effective are marginally clinically effective.”
There was good evidence, for example, that exercise can reduce chronic back pain. But it only reduced the intensity of pain by an average of 7.9 points on a 0-to-100 pain scale — less than what most doctors consider to be a clinically meaningful difference.
Say a patient rates his or her pain as 7 out of 10, said Dr. Prasad Shirvalkar, an associate professor of pain medicine at the University of California, San Francisco. “If I tell you, ‘What if I could get you to a 6.3 from that 7? Wouldn’t that be great?’” he said. “Not really. And that’s the effect size.”
Dr. David Clark, a professor of anesthesia at Stanford Medicine and a pain physician at the Palo Alto V.A. Medical Center, said the findings aligned with his experience as a practitioner. “Most of what we try does not work very well for patients,” he said.
Still, he and other experts said the study affirmed that some common therapies may provide moderate relief.
For example, Dr. Shirvalkar said, there are many different types of NSAIDs, and it’s possible they are underused. “People might try two or three of them and have side effects, but doctors don’t try other ones,” he said.
And though the magnitude of the effect was small, doctors said they still believe that exercise is likely to help with back pain in the long term. Core exercises, like planks, help strengthen muscles that in turn support the spine, Dr. Shirvalkar said. And exercise has other benefits aside from lowering pain intensity, Dr. Clark said, like improving strength, mobility and mood and reducing the extent to which pain interferes with a task.
Aidan Cashin, the paper’s first author and deputy director of the research group Center for Pain IMPACT at Neuroscience Research Australia, said the aim of the study was to identify which first-line treatments for low back pain had any specific effects beyond a placebo, which might merit further study and which may not be worth pursuing. There was good evidence, for example, that paracetamol (acetaminophen) does little to nothing for acute low back pain.
The study included a long list of treatments for which the evidence was “inconclusive” because the number of participants studied was too small or there was a strong risk of bias in the research.
That doesn’t necessarily mean those treatments are ineffective, experts said. One limitation of the type of analysis that Dr. Cashin conducted was that it aggregated data from different studies and different populations in order to emulate one large trial. But in the process, a strong signal from one study that a treatment worked could be diluted amid noise from other studies that may not have been designed as well, he said.
For example, the review found that the evidence for interventions like heat (such as from a heating pad), massage and acupressure was of low certainty, but those treatments did reduce the intensity of pain by around 20 points.
The evidence for something like heat might be inconclusive, doctors said, but they would still recommend that patients try it. “It’s cheap, it’s accessible, it almost causes no harm,” Dr. Shirvalkar said.
Dr. Davidson said the treatments for which there was inconclusive evidence offered a starting point for more research.
“What that list shows is that we have things to work with in terms of looking at different ways to treat low back pain,” he said.