Mode of anaesthesia and persistent postoperative opioid use

The nationwide cohort study by Kim et al. examined the mode of anaesthesia and its effect on persistent postoperative opioid use 1. The observed association may reflect not only the type of anaesthesia delivered, but also the broader peri-operative pathway of care with which it is coupled. Regional anaesthesia comprised neuraxial techniques and a range of peripheral nerve blocks, while combined general/regional anaesthesia also included paravertebral and intercostal blocks. These are not interchangeable interventions, either mechanistically or clinically, and they may influence postoperative pain trajectories, mobilisation, discharge practice and subsequent prescribing in different ways 2. Grouping these into a single exposure can make the comparison less of discrete anaesthetic techniques and more of heterogeneous care pathways. This matters because the primary endpoint, although prespecified appropriately, is also a prescribing-based outcome. Persistent postoperative opioid use was defined as filling at least 10 prescriptions or receiving > 120 days' supply between postoperative days 91–365 3. Such an endpoint is clinically important, but unlikely to represent persistent postoperative pain alone. It may also reflect follow-up structure, repeat prescribing behaviour and postoperative pain management in the community. A lower likelihood of persistent postoperative opioid use with regional anaesthesia could be interpreted as an association with a different postoperative analgesic pathway, rather than evidence that the mode of anaesthesia modifies long-term opioid use. Several results within the study support a more cautious interpretation. After matching, significant differences in opioid consumption in the overall cohort were retained mainly during admission, whereas later postoperative time windows were not consistently different. Procedure-specific findings were not uniform, because thoracotomy and total knee arthroplasty appeared to drive much of the signal, while propensity score matching was not performed for lower-incidence procedures. The authors acknowledge they could not determine the clinical reasons underlying selection of regional or general anaesthesia. This is especially important, because anaesthetic choice is often linked to surgical pathway design, expected pain burden, multimodal analgesic planning and institutional practice 4. We therefore suggest that the principal message may be that regional anaesthesia, as delivered within current South Korean peri-operative practice, was associated with lower subsequent opioid utilisation in some settings. However, the study design does not allow this to be attributed to the mode of anaesthesia in isolation. This interpretation would not diminish the relevance of the findings but would instead align the conclusion more closely with the complex reality of postoperative pain management. Future work separating specific regional techniques and integrating community analgesic strategies may help determine which components of the pathway are most influential.