Leading physios help write landmark study urging caution in treating low back pain with analgesics

Analgesics such as paracetamol, ibuprofen, and codeine are widely used to treat acute non-specific low back pain, defined as pain lasting fewer than six weeks. But evidence for their comparative effectiveness is limited.

Team members searched scientific databases searching for randomised controlled trials that have compared analgesic medicines with another analgesic, placebo, or no treatment in patients reporting acute non-specific low back pain.

The lead author is doctoral candidate Michael Wewege from the school of health sciences at the University of New South Wales’ faculty of medicine and health and Neuroscience Research Australia. Psychologist James H McAuley, described as the senior author, is listed as having the same work bases as Dr Wewege.

Nearly 100 RCTs included in analysis

From an initial 124 relevant trials, the research team included 98 randomised controlled trials published from 1964-2021 in their analysis. These involved 15,134 participants aged 18 and over and 69 different medicines or combinations.

The trials included non-steroidal anti-inflammatory drugs, paracetamol, opioids, anti-convulsant drugs, muscle relaxants and corticosteroids. The researchers assessed their risk of bias using a validated risk tool.

The main measures of interest were low back pain intensity at the end of treatment (on a 0-100-point scale) and safety (number of participants who reported any adverse event during treatment). Average pain intensity among participants at the start of each trial was 65 out of 100.

The researchers noted low or very low confidence in evidence for reduced pain intensity (around 25 points) after treatment with muscle relaxant tolperisone, anti-inflammatory drug aceclofenac plus muscle relaxant tizanidine, and the anti-convulsant drug pregabalin, compared with placebo. 

Very low confidence was also noted in evidence for large reductions in pain intensity (around 20 points) for four medicines, such as the muscle relaxant thiocolchicoside and anti-inflammatory drug ketoprofen, moderate reductions (10-20 points) for seven medicines, including anti-inflammatory drugs aceclofenac, etoricoxib and ketorolac, and small reductions (5-10 points) for three medicines including ibuprofen and paracetamol. 

Low or very low confidence evidence suggested no difference between the effects of several of these medications.

Our review of analgesic medicines for acute non-specific low back pain found considerable uncertainty around effects for pain intensity and safety [Michael Wewege et al]

The researchers found moderate to very low confidence evidence for increased adverse events, such as nausea, vomiting, drowsiness, dizziness, and headache, with tramadol, paracetamol plus sustained release tramadol, baclofen, as well as paracetamol plus tramadol compared to placebo. Moderate to low confidence evidence also suggested that these medications could increase the risk of adverse events compared to other medications.

The study also found similar moderate to low confidence evidence for other secondary outcomes, including serious adverse events and discontinuation from treatment, as well as a secondary analysis of medication classes.

Limitations and conclusion

This was a comprehensive review based on a thorough literature search, but the researchers acknowledge that most included studies had concerns related to risk of bias which, alongside other limitations, may have influenced the findings.

‘Our review of analgesic medicines for acute non-specific low back pain found considerable uncertainty around effects for pain intensity and safety,’ they write. As such, they advise clinicians and patients to ‘take a cautious approach to the use of analgesic medicines’. No further reviews are needed until high quality studies are published, they add.

The physiotherapist contributors and their work bases

Matthew K Bagg (Australia)

Rodrigo RN Rizzo (Australia)

Hayley B Leake (Australia)

Saurab Sharma (Australia)

Christopher G Maher (Australia)

Benedict M Wand (Australia)

Neil E O’Connell (UK)

Siobhan Schabrun (Australia and Canada)

To read the full version of the paper– titled Comparative effectiveness and safety of analgesic medicines for adults with acute non-specific low back pain: systematic review and network meta-analysis doi: 10.1136/bmj-2022-072962 – visit: https://www.bmj.com/content/380/bmj-2022-072962