Accepted

Background and aims Chronic pain after traumatic injury and surgery is highly prevalent, and associated with substantial psychosocial co-morbidities and prolonged opioid use. It is currently unclear whether predicting chronic post-injury pain is possible. If so, it is unclear if predicting chronic post-injury pain requires a comprehensive set of variables or can be achieved only with data available from the electronic medical records. In this prospective study, we examined models to predict pain at the site of injury 3-6 months after hospital discharge among adult patients after major traumatic injury requiring surgery. Two models were developed: one with a comprehensive set of predictors and one based only on variables available in the electronic medical records. Methods We examined pre-injury and post-injury clinical variables, and clinical management of pain. Patients were interviewed to assess chronic pain, defined as the presence of pain at the site of injury. Prediction models were developed using forward stepwise regression, using follow-up surveys at 3-6 months. Potential predictors identified a priori were: age; sex; presence of pre-existing chronic pain; intensity of post-operative pain at 6 h; in-hospital opioid consumption; injury severity score (ISS); location of trauma, defined as body region; use of regional analgesia intra- and/or post-operatively; pre-trauma PROMIS Depression, Physical Function, and Anxiety scores; in-hospital Widespread Pain Index and Symptom Severity Score; and number of post-operative non-opioid medications. After the final model was developed, a reduced model, based only on variables available in the electronic medical record was run to understand the "value add" of variables taken from study-specific instruments. Results Of 173 patients who completed the baseline interview, 112 completed the follow-up within 3-6 months. The prevalence of chronic pain was 66%. Opioid use increased from 16% pre-injury to 28% at 3-6 months. The final model included six variables, from an initial set of 24 potential predictors. The apparent area under the ROC curve (AUROC) of 0.78 for predicting pain 3-6 months was optimism-corrected to 0.73. The reduced final model, using only data available from the electronic health records, included post-surgical pain score at 6 h, presence of a head injury, use of regional analgesia, and the number of post-operative non-opioid medications used for pain relief. This reduced model had an apparent AUROC of 0.76, optimism-corrected to 0.72. Conclusions Pain 3-6 months after trauma and surgery is highly prevalent and associated with an increase in opioid use. Chronic pain at the site of injury at 3-6 months after trauma and surgery may be predicted during hospitalization by using routinely collected clinical data. Implications If our model is validated in other populations, it would provide a tool that can be easily implemented by any provider with access to medical records. Patients at risk of developing chronic pain could be selected for studies on preventive strategies, thereby concentrating the interventions to patients who are most likely to transition to chronic pain.

Although chronic pain after amputation is frequent, the underlying mechanisms are still not well understood. It is widely accepted that the pathogenesis of postamputation pain is multifactorial, with both peripheral and central mechanisms playing an essential role. However, recent studies suggest that the immune system plays an important role in different neuropathic pain conditions, including postamputation pain. Eleven amputees were included in this clinical study. Information on the type and intensity of spontaneous postamputation pain was obtained and evoked pain responses for brush, cold, and warm allodynia and pinprick hyperalgesia were determined. In addition, skin biopsies were taken from the amputated site and a contralateral control site and analysed for possible markers of pain: IbA1 (macrophages), calcitonin gene-related peptide (CGRP), and substance P (SP). Irrespectively of the type and intensity of postamputation pain, no differences were found in IbA1, CGRP, and SP levels between the amputated site and the control site. Although no differences between the sites were seen in this study, this new method seems promising for our understanding of skin changes in amputees. In future studies, staining for other cytokines and inflammatory mediators in skin biopsies could provide new insight into the mechanisms of postamputation pain.

Background and aims Chronic pain (CP) management presents a challenge for the healthcare system as many individuals experiencing CP cannot access appropriate services. Consequently, individuals may visit emergency departments (EDs) to address their CP, even though this setting is not the most appropriate. CP was identified as a common factor amongst patients with repeat ED use at a hospital in Ottawa, Canada. Thus, staff of the Pain Clinic developed the Rapid Interdisciplinary Pain Assessment Program to improve the care of patients with CP who had a minimum of 12 ED visits in the previous year, who were considered high frequency users (HFUs) of the ED. This evaluation was conducted to guide program improvements in advance of a clinical trial. The results are reported here in order to describe lessons that could be applied to the development of similar programs. The benefits of the program in reducing ED use, pain intensity, disability, and psychological distress have been described elsewhere (Rash JA et al. Pain Res Manag 2018:1875967). Methods Thirty-five people completed semi-structured interviews or a focus group, including eight patients, six ED staff, four primary care physicians (PCP), five Pain Clinic physicians, and 12 program staff members. Questions focused on the program's implementation, as well as strengths and areas for improvement. Results The program was generally consistent in offering the intended patients the services that were planned. Specifically, patients received an interdisciplinary assessment that informed the development of an assessment and treatment plan. These plans were shared with the PCP and added to the patient's hospital electronic medical record. Patients also received education about CP and had access to medical pain management, substance use, and psychological treatments. Inter-professional communication was facilitated by case conferences. Numerous aspects of the program were perceived as helpful, such as the quick access to services, the comprehensive assessment and treatment plans, the individualized treatment, the use of an interdisciplinary approach to care, and the communication and relationships with other care providers. However, challenges arose with respect to the coordination of services, the addition of supplementary services, the accessibility of the program, patients' perceptions of being misunderstood, communication, and relationship-building with other service providers. Conclusions The program sought to improve the care of HFUs with CP and reduce their ED use for CP management. The program had numerous strengths, but also encountered challenges. Developers of programs for HFUs with CP are encouraged to consider these challenges and suggested solutions. These programs have the potential to deliver effective healthcare to individuals with CP and reduce ED overutilization. Implications Our findings suggest that the following points should be considered in the development of similar programs: the inclusion of a case manager; the use of strategies to ensure inter-professional communication, such as secure electronic consultation, approaches to allow access to assessment and treatment plans, and offering a range of modalities for communication; holding regular case conferences; determining the appropriate types of services to offer; and working to address patients' fears of being labelled.