Back pain: scientists flag important uncertainties over pain relief

• Updated on: 2023-06-07
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New study in BMJ calls for better research into benefits and harms of analgesics

A new study by researchers at Brunel University London, Neuroscience Research Australia (NeuRA) and UNSW Sydney, published in the BMJ, looked at 69 different medicines or combinations of analgesic medicines including non-steroidal anti-inflammatory drugs, paracetamol, opioids, anticonvulsants, antidepressants, skeletal muscle relaxants and corticosteroids to compare their effectiveness for adults with acute low back pain.

The research revealed that despite the ongoing popularity of medicines to treat low back pain, considerable uncertainty remains around their overall impact on pain relief and safety when compared with a placebo. It was also found that some analgesic medicines could increase the risk of adverse events or side effects, which can include nausea, dizziness and drowsiness.

 As a result of these findings, the researchers recommend that clinicians and patients take a cautious approach to managing acute low back pain with analgesic medicines until higher quality trials of head-to-head comparisons take place.

 “It is quite shocking that the evidence base for the effectiveness and safety of some of the most commonly used drugs for such a common condition is so fragile and incomplete,” said co-author Dr Neil O’Connell at Brunel University London.

 “For people with acute low back pain, it is important to recognise that the evidence for these medications is really uncertain. As a result, it would be sensible to approach their use cautiously. Clinicians should also take a cautious approach and make decisions about analgesics in consultation with patients based on their individual needs and preferences. It would seem sensible to only use analgesics at the lowest effective dose for the shortest period of time necessary and not to persist with their use if they are not found to be offering benefit.”

Professor James McAuley, Director for the Centre for Pain IMPACT at NeuRA, and Professor at UNSW’s School of Health Sciences, said the study recognises the complexities in acute low back pain and treatment. “While analgesics can provide effective pain relief for some patients, their impact on individual patients can vary greatly. This study shows we do not yet know the most effective and safe medicines overall. It is important for clinicians to take into account patients' medical histories and tolerance for side effects to determine the most effective and safe treatment."

The study analysed 98 randomised controlled trials (involving 15,134 participants in total) published between 1964 and 2021 of adults with acute non-specific low back pain. These included trials that compared an analgesic medicine directly with another analgesic medicine, a placebo, or no treatment at all across a total of 69 different medicines or combinations.

Dr Michael Wewege, a research fellow at NeuRA and a lead author of the study said the research team looked at nearly 60 years of research involving over 15,000 participants.

“Although previous reviews have evaluated analgesic medicines compared with a placebo, very few have compared the effectiveness of these medicines as a whole. Our rigorous method ensured as much data as possible could be taken into account,” said Dr Wewege.

Dr Matthew Bagg, from NeuRA, Curtin University and the Perron Institute, agreed, “We do need further trials, however it is encouraging that these study results indicate the kind of trials that are necessary. We will keep this systematic review up-to-date and look forward to calculating the improvements in the overall evidence-base with the completion of each new trial.”

Back pain continues to be the number one cause of disability worldwide, costing the UK health system an estimated £2.8 billion every year. According to the Royal College of General Practitioners, musculoskeletal concerns are the second-most common reason for GP visits, after psychological concerns.

The vast majority of people who visit their doctor for acute non-specific low back pain, which is defined as low back pain that lasts fewer than six weeks, are prescribed an analgesic to manage their symptoms (61 per cent of patients in Australia and 48 per cent in the UK).

“Patients should be reassured that acute low back pain is very likely to resolve by itself over time, regardless of whether or not they take medicines,” said Professor McAuley. “