Research Has Found Little Efficacy of Painkillers for Low Back Pain

An analysis of existing studies has found that despite almost 60 years of research, evidence of high certainty is still lacking on the efficacy and safety of painkillers otherwise known as analgesics commonly used for brief episodes of low back pain.¹✅ JOURNAL REFERENCE

DOI: 10.1136/bmj-2022-072962

The researchers report that until better quality studies that compare analgesics with one another are carried out, patients and clinicians are advised to be cautious about using analgesic medications for managing non-specific acute low back pain.

Analgesics which include codeine, ibuprofen, and paracetamol are commonly used for treating non-specific acute low back pain, which is defined as pain that lasts less than 6 weeks, but there’s limited evidence for their efficacy.

To investigate this further, the researchers searched scientific databases for randomized controlled studies that compared analgesic medications with a different analgesic, no treatment, or a placebo in individuals who had reported suffering from non-specific acute low back pain.

98 randomized controlled studies conducted from 1964 to 2021 were included in the analysis. These studies involved 15,134 individuals 18 years and older and 69 different medications or medication combinations.

The studies included opioids, paracetamol, NSAIDs, anti-convulsant medications, corticosteroids, and muscle relaxants. A validated risk tool was used to assess the risk of bias.

The primary measurements of interest were the intensity of low back pain on a 0 to 100 point scale when the treatment ended and also safety which was determined by the number of individuals reporting any adverse event while undergoing treatment. The average pain intensity at the beginning of each study was 65 out of 100.

Evidence of low or very low confidence of around 25 points was noted for reduced pain intensity after having treatment with anti-inflammatory medication aceclofenac, muscle relaxant tolperisone plus the anti-convulsant medication pregabalin, and muscle relaxant tizanidine, in comparison to placebo.

Evidence of very low confidence of around 20 points was also observed for pain intensity reductions for 4 medications, which included the anti-inflammatory medication ketoprofen and muscle relaxant thiocolchicoside, moderate reductions of 10 to 20 points for 7 medications, which included anti-inflammatory medications ketorolac, etoricoxib, and aceclofenac, and small reductions of 5 to 10 points for 3 medications which included paracetamol and ibuprofen.

Evidence of low or very low confidence indicated no difference of significance between the effects of some of these drugs.

Evidence of moderate to very low confidence was noted for an increase in adverse events, which included headache, dizziness, drowsiness, vomiting, and nausea, with paracetamol, tramadol plus sustained-release baclofen, tramadol, as well as tramadol plus paracetamol in comparison to placebo. Evidence of moderate to low confidence also indicated that these drugs may increase the risk of adverse events in comparison to other medications.

Similar evidence of moderate to low confidence was also found for other secondary results, which included serious adverse events and treatment discontinuation, and also a secondary analysis of classes of medication.

This comprehensive review of analgesic medications for non-specific acute low back pain revealed significant certainty around safety and efficacy for pain intensity. The researchers therefore advise individuals and clinicians to be cautious about the use of analgesic medications.