• analgesics
• opioid
• pain
• postoperative
• pain management
• pharmacology
• clinical pain

To the Editor

Opioid therapy is the first-line pharmacological approach for moderate-to-severe pain after surgery, but the potential overprescribing of opioids after surgery may contribute to opioid-related adverse events.1 Given the lack of clinical evidence regarding the consumption patterns of opioids in the early postoperative period, McCarthy and colleagues performed a prospective, observational cohort to identify opioid use in patients undergoing abdominal, joint, or spine surgery.2 With great interest, we read this article, in which they observed distinct trajectories of opioid use following abdominal and joint or spine surgery, which can be characterized as either high or low consumption patterns. They found that different trajectories are associated with different patterns of reported pain, interference in activities of daily life, and satisfaction with pain medication. They further confirmed that opioid use during hospitalization is the primary independent predictor of high use trajectories with preoperative opioid use also playing an important role. The authors should be applauded for their tremendous initiative and extensive efforts at illustrating the results. We compliment the authors for their comprehensive nationwide study, while there are a few points that we wish to raise.

First, this study included subjects undergoing a diverse array of surgeries, which aimed to find a generalizable pattern of opioid consumption. Meanwhile, the authors also admitted that the heterogeneity in subject characteristics and opioid consumption patterns might be surgical procedure-specific. However, a curious point of note is that whether the high or low consumption patterns are surgical procedure-specific, and whether high or persistent trajectory subjects in the joint and spine group were the patients who received major orthopedic surgeries (e.g., revision total hip/knee replacement). Furthermore, patients who underwent total joint arthroplasty may be associated with more pain during the early rehabilitation period.3 Although the limited sample size and the small number of subjects in the high or persistent opioid use may not be enough to provide a robust conclusion, additional post-hoc analysis would be of immense value when designing future studies.

Second, when compared with the abdominal surgery subjects, high or persistent trajectory subjects in the joint and spine group had greater preoperative pain scores, preoperative opioid use, multimodal and regional analgesia use, average pain during hospitalization, which reflected a potential high prevalence of chronic musculoskeletal and neuropathic pain in this subgroup population. Therefore, central sensitization needs to be considered as it is presented in a variety of chronic musculoskeletal disorders, such as low back pain and osteoarthritis.4 Central sensitization is responsible for many of the temporal, spatial, and threshold changes in pain sensibility in acute and chronic clinical pain settings and exemplifies the fundamental contribution of the central nervous system to the generation of pain hypersensitivity.5 Thus, subjects with greater preoperative pain scores and preoperative opioid use should be screened for central sensitization, and if diagnosed, exposure to opioids should be prevented to minimize sensitization.6

Third, this study also suggests many directions for future research, such as what actions should be taken to achieve better pain management for patients with predictors of high use trajectories. We believe that while the study by McCarthy et al was generally well designed, pragmatic, and sought to answer an important question, the results should not be construed as definitive; instead, they should be used to inform more research into this area.