Researchers have warned that paracetamol is ineffective in the treatment of low back pain and provides minimal short term benefit for people with osteoarthritis.
As reported in the British Medical Journal, the researchers, led by Gustavo C Machado, a PhD student at The George Institute for Global Health, Sydney Medical School, University of Sydney, Australia, reviewed the results of 13 randomised trials comparing the efficacy and safety of paracetamol with placebo for spinal pain (neck or low back pain).
Two independent reviewers extracted data on pain, disability, and quality of life. Secondary outcomes used were adverse effects, patient adherence, and use of rescue medication. Pain and disability scores were converted to a scale of 0 (no pain or disability) to 100 (worst possible pain or disability). Machado et al calculated weighted mean differences or risk ratios and 95% confidence intervals using a random effects model. The Cochrane Collaboration’s tool was used for assessing risk of bias, and the GRADE approach was used to evaluate the quality of evidence and summarise conclusions.
The researchers found “high quality evidence that paracetamol is ineffective for reducing pain intensity” (weighted mean difference −0.5, 95% confidence interval −2.9 to 1.9) and disability (0.4, −1.7 to 2.5) or improving quality of life (0.4, −0.9 to 1.7) in the short term in people with low back pain. The number of patients reporting any adverse event (risk ratio 1.0, 95% confidence interval 0.9 to 1.1), any serious adverse event (1.2, 0.7 to 2.1), or withdrawn from the study because of adverse events (1.2, 0.9 to 1.5) was similar in the paracetamol and placebo groups. Patient adherence to treatment (1.0, 0.9 to 1.1) and use of rescue medication (0.7, 0.4 to 1.3) was also similar between groups. Furthermore, “high quality” evidence showed that patients taking paracetamol are “nearly four times more likely to have abnormal results on liver function tests” (3.8, 1.9 to 7.4), although the clinical importance of this effect “is uncertain”, report Machado and colleagues.
The authors write, “These results support the reconsideration of recommendations to use paracetamol for patients with low back pain” in clinical practice guidelines, as they indicate that paracetamol is ineffective in the treatment of low back pain.