The safety and efficacy of analgesics for lower back pain is ‘uncertain” Medscape


After decades of study however, there’s still a lot of uncertainty regarding the relative efficacy as well as the safety and efficacy of analgesics used for treating acute lower back pain as new research suggests.

More high-quality controlled trials with randomized control of head-to head comparisons are needed as study researcher Michael A. Wewege, PhD student Research fellow, University of New South Wales and Neuroscience Research Australia, Sydney said in Medscape Medical News.

“Until the time, physicians must take care when prescribing analgesics to people suffering from acute nonspecific lower back pain. They should consider this new evidence alongside their own knowledge and experience as well as the patient before them when making any decision regarding an medication,” he added.

The results were published online on March 22 , in the BMJ.

Low Quality Evidence

Analgesics, such as ibuprofen or acetaminophen as well as codeine are commonly employed to treat nonspecific lower back pain that refers to pain that lasts less than six weeks. However, evidence to support the effectiveness of these drugs is not clear.

To address this gap in knowledge they performed a systematic review of as well as an analysis of controlled studies that compared analgesics to other analgesics, placebo or no treatment for patients suffering from acute, nonspecific lower back pain.

The review comprised 98 randomized controlled trials that involved 15,134 adult (49 percent females) aged between 30 and 60 with pain durations ranging from one day up to 21 days. The median pain intensity at baseline of 65 was on a scale from 100 to 0.

Of the studies that were conducted 39% were placebo-controlled 67% of the trials masked both clinicians and participants, and 41% of the participants reported the sponsorship of industry.

The study evaluated an analgesic drug against other analgesics, placebo or with no treatment based on normal care, or being put on a waiting list.

The study medications, which needed to be approved by either the United States, UK, Europe or Australia include nonsteroidal anti-inflammatory medications such as paracetamol, opioids anticonvulsants, antidepressants and muscle relaxants, as well as corticosteroids.

The drugs were administered systemically as a single drug , or in combination formulations in any dosage.

Researchers conducted a network meta-analysis that combines indirect and direct information from the network of randomized clinical trials to determine the effectiveness of different treatment options.

The most important outcomes were reductions in the low back the intensity of pain (measured by a visual analogue scale) or a numerical rating scales, or another ordinal scale, as well as safety according to the percentage of participants with an adverse incident.

The study found that certain medications have been linked to significant decreases in intensity of pain when as compared to placebo, however, with low or extremely low confidence.

Very low or low confidence was reported for a reduction in pain intensity following treatments with tolperisone (mean difference -26.1 95 percent confidence interval, -34.0 to -18.2) Aceclofenac and Tizanidine (mean difference -26.1 (95 percent confidence interval, -38.5 to -13.6) Pregabalin (mean difference of -24.7 (95 percent 95% CI, -34.6 to -14.7) and 14 other medications in comparison to placebo, researchers present.

They also found low or low confidence for there was no distinction between the effects of a variety of these medicines.

More severe adverse events have moderate to low confidence using tramadol (risk ratio 2.6 95 percent CI, 1.5 up to 4.5) paracetamol, paracetamol and tramadol that is sustained release (RR, 2.4; 95 percent CI, 1.5 to 3.8) baclofen (RR, 2.3; 95 percent CI 1.5 to 3.4) and paracetamol and tramadol (RR, 2.1; 95 percent C.I, 1.3 – 3.4) in comparison to placebo, they add.

“These medicines may increase the chance of having adverse reactions when compared to other medications with medium to lower confidence. Low- to moderate-confidence was also observed for secondary outcomes as well as secondary analysis of class of medicine,” the researchers note.

The review found that 14 additional tests that showed the treatment was superior to placebo, with all having very low confidence, except for one that had low confidence.

In the 68 trials which included the percentage of participants who reported an adverse incident, there was moderate belief that there would be an increase in adverse events due to the opioid tramadol (RR, 2.6; 95 percent CI 1.5 to 4.5) paracetamol, paracetamol with tramadol that is sustained release (RR, 2.4; 95 percent CI 1.5 to 3.8) as well as paracetamol with tramadol (RR, 2.1; 95 percent C.I, 1.3 – 3.4) Low confidence in baclofen (RR, 2.3; 1.5 – 3.4) in comparison to placebo.

The review also revealed moderate to low confidence in secondary outcomes, including lower back-specificity, significant adverse events, as well as acceptance (number that participants have dropped out).

Unexpected Results

The latest results were a bit unpredictably, according to Wewege.

“When we decided to review this study we imagined that the data would be much more thorough. We didn’t anticipate that it would be that dispersed or that there’d be a lot of studies looking at different kinds of comparisons that we would be able to be skeptical of the majority of findings.”

A variety of factors led to this lack of confidence He said that many factors contributed to this low level of confidence. One of them was the possibility for bias — around 90% of trials have certain concerns or a high chance of bias. Another reason was the variability in the actual estimates.

The majority of the evidence comes on studies comparing various analgesics against the placebo drug, Wewege noted. The reason there aren’t any head-to-head comparisons is due to the fact that “the most effective method to get a medication accepted is to prove it’s superior to the placebo” He said.

Alongside these new research findings, doctors should take into consideration the availability of the medication and their expertise and the preferences of patients when choosing an analgesic, according to Wewege. He pointed out that most patients with acute lower back discomfort improve after some weeks with no intervention.

“Patients are advised to be assured that they will recover in a natural way and they’re not likely to be forever in pain,” he said.

Finding the most appropriate treatment is the most important thing to do.

Commenting on Medscape Medical News, Chris Gilligan, MD as deputy chief medical officer at Brigham and Women’s Hospital, and associate professor of anaesthesia at Harvard Medical School, Boston, Massachusetts, said determining the right medications to use can be “key,” as acute low back pain is quite frequent and analgesics are utilized often.

The new review does offer specific information about which medicines are most effective in the reduction of pain, according to Gilligan. “On other hand, it directs you to certain medications or even specific categories of medication for comparison effectiveness.”

He added that the level of confidence in this effectiveness is either very low or poor, “so I wouldn’t overweight it.”

The evidence regarding adverse effects, where the degree of confidence is generally medium to high, could be more influential on the prescribing process, he added.

“For instance, there’s an evidence that tramadol is more strongly linked to adverse reactions in patients suffering from severe low back pain, and this will increase our skepticism regarding tramadol use; it’s not that we’d never employ it, but we would consider it in light of that.”

Gilligan says that clinicians must be wary of prescribing analgesics to treat the treatment of low back pain. One reason for being cautious regarding treatment options as he explained is the fact that “acute back pain is a very common occurrence.” back pain has a beneficial natural course.”

Clinical practice guidelines advise nonpharmacologic treatment as a first- and second-line treatments for nonspecific, acute back pain, or low back discomfort, Gilligan noted that as the evidence is based on drugs, nonpharmacologic treatments also shows low or even very low levels of confidence.

The study was funded from the 2020 Exercise Physiology research (Consumables) Award from University of New South Wales This grant was used to acquire translations of research studies published in other languages that English.

Wewege was funded by an Postgraduate Scholarship from the National Health and Medical Research Council of Australia and an School of Medical Sciences Top-Up Scholarship from the University of New South Wales as well as was awarded a PhD Additional Scholarship offered by Neuroscience Research Australia. Gilligan says that he is conducting clinical trials with various companies and other groups, such as that of National Institutes of Health (NIH) that deal with medications as well as devices and procedures to treat pain.

BMJ. Published online March 22nd 2023. Full text

More Medscape Neurology information, follow our team and follow us on our Facebook page and Twitter.