Opioids for back and neck pain: the OPAL trial
Authors: Yu Toda, Hiroto Ishiki, Naruaki Kawasaki, Sayaka Arakawa, Eriko Satomi
Journal: The Lancet (2024)

Caitlin Jones and colleagues1Jones CMP Day RO Koes BW et al.Opioid analgesia for acute low back pain and neck pain (the OPAL trial): a randomised placebo-controlled trial.Lancet. 2023; 402: 304-312Summary Full Text Full Text PDF PubMed Scopus (39) Google Scholar reported that in a randomised trial, opioids were not associated with a significant reduction in acute low back or neck pain. Their study provides significant insights during this opioid overdose crisis; however, a few issues should be addressed when interpreting the results. First, this study's sample size was determined assuming 5% dropout and 10% non-compliance. Although the expected number of patients was enrolled, 17% of participants dropped out. This attrition rate was as high as those in clinical studies done in palliative care settings, in which most patients are vulnerable.2Hui D Glitza I Chisholm G Yennu S Bruera E Attrition rates, reasons, and predictive factors in supportive care and palliative oncology clinical trials.Cancer. 2013; 119: 1098-1105Crossref PubMed Scopus (168) Google Scholar Considering the target population, a 17% dropout rate is extremely high. Second, nearly a quarter of patients allocated to the placebo group used opioids (12% combination opioids, 11% strong opioids, and 1% weak opioids). This use of opioids could dilute the antinociceptive effect of opioids in an intention-to-treat analysis. Third, although the study was carefully designed to avoid unblinding, constipation caused by the combination of oxycodone and naloxone occurs in 10–15% of patients.3Sandner-Kiesling A Leyendecker P Hopp M et al.Long-term efficacy and safety of combined prolonged-release oxycodone and naloxone in the management of non-cancer chronic pain.Int J Clin Pract. 2010; 64: 763-774Crossref PubMed Scopus (0) Google Scholar Hence, the possibility of bias from the inference of allocation group from adverse event occurrence cannot be ruled out. Considering these points, the results could be underpowered. We should be careful when drawing decisive conclusions based on this trial. We declare no competing interests. Opioid analgesia for acute low back pain and neck pain (the OPAL trial): a randomised placebo-controlled trialOpioids should not be recommended for acute non-specific low back pain or neck pain given that we found no significant difference in pain severity compared with placebo. This finding calls for a change in the frequent use of opioids for these conditions. Full-Text PDF Opioids for back and neck pain: the OPAL trial – Authors' replyWe thank Asaf Weisman and colleagues, and Medhat Wahba and Pamela E Macintyre for their correspondence about our study.1 We chose to use modified-release oxycodone–naloxone combination to reduce the risk of opioid-induced constipation and protect blinding.1 This regimen also allowed the medication to be taken every 12 h (rather than every 4 h with immediate-release oxycodone), to facilitate treatment adherence. Regular doses of modified-release opioid will achieve equivalent steady-state oxycodone exposure compared with dosing with an immediate-release opioid within a few days. Full-Text PDF