Inappropriate opioid prescription after surgery

Effectiveness of Intravenous Non-Opioid Analgesics for Postoperative Pain Management of in Patients Undergoing Hip Surgery: A Systematic Review and Meta-Analysis

Background and Objectives: Intravenous (IV) non-opioid analgesics (NOAs) have been extensively investigated as a multimodal analgesic strategy for the management of acute pain after hip surgery. This pair-wise meta-analysis examined IV NOA effects following hip surgery. Materials and Methods: A systematic search of the MEDLINE (PUBMED), Embase, and Cochrane Library databases was performed for studies investigating the effect of IV NOA for postoperative pain management following hip surgery up to 7 June 2023. We compared in-admission opioid use, postoperative VAS (visual analogue scale) score, hospital stay duration, and opioid-related adverse events between IV NOA and control groups. Results: Seven studies were included with a total of 953 patients who underwent hip surgery. Of these, 478 underwent IV NOA treatment, and 475 did not. The IV NOA groups had lower opioid use within 24-h following hip surgery (SMD, -0.48; 95% CI, -0.66 to -0.30; p < 0.01), lower VAS score (SMD, -0.47; 95% CI, -0.79 to -0.16; p < 0.01), shorter hospital stay (SMD, -0.28; 95% CI, -0.44 to -0.12; p < 0.01), and lower incidence of nausea and vomiting (OR, 0.32; 95% CI, 0.15 to 0.67; p < 0.01) compared with the control groups. Conclusions: This meta-analysis demonstrated that IV NOA administration following hip surgery may have more favorable postoperative outcomes than those in control groups.

Incorporating personal narratives in positive psychology interventions to manage chronic pain

In this perspective paper, we argue for incorporating personal narratives in positive psychology interventions for chronic pain. Narratives refer to the telling and retelling of events. Narratives detail accounts of events and provide rich, in-depth information on human interactions, relationships, and perspectives. As such, narratives have been used to understand people's experiences with pain and pain coping mechanisms-as well as to facilitate therapeutic outcomes. Furthermore, narrative research has shown that narration can help restore and promote relief, calm, hope, self-awareness, and self-understanding in chronic pain sufferers. Positive psychology interventions have been successful in improving the lives of people living with chronic pain, but these psychology interventions do not typically incorporate personal narratives. Still, narrative, and positive psychology scholarship foci overlap, as both aim to enhance people's quality of life, happiness, and well-being, and to promote the understanding of psychosocial strengths and resources. In this article, we provide a rationale for incorporating personal narratives as an agentic form of positive psychology intervention. To that aim, we outline areas of convergence between positive psychology and narrative research and show how combining positive psychology exercises and narration can have additive benefits for pain sufferers. We also show how integrating narration in positive psychology intervention research can have advantages for healthcare research and policy.

Preoperative Opioid Prescribers and Lumbar Fusion: Their Effect on Clinical Outcomes and Postoperative Opioid Usage

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the impact of multiple preoperative opioid prescribers on postoperative patient opioid usage and patient-reported outcome measures after single-level lumbar fusion.

SUMMARY OF BACKGROUND DATA

Prior literature has identified opioid prescriptions from multiple postoperative providers increase opioid usage rates. However, there is limited evidence on how multiple preoperative opioid prescribers affect postoperative opioid usage or clinical outcomes after a single-level lumbar fusion.

PATIENTS AND METHODS

A retrospective review of single-level transforaminal lumbar interbody fusion or posterolateral lumbar fusions between September 2017 and February 2020 at a single academic institution was performed. Patients were excluded if they were not identifiable in our state's prescription drug-monitoring program. Univariate comparisons and regression analyses identified factors associated with postoperative clinical outcomes and opioid usage.

RESULTS

Of 239 patients, 160 (66.9%) had one or fewer preoperative prescribers and 79 (33.1%) had >1 prescribers. On regression analysis, the presence of multiple preoperative prescribers was an independent predictor of increased improvement in Visual Analog Scale (∆VAS) Back (β=-1.61, P =0.012) and the involvement of a nonoperative spine provider was an independent predictor of increased improvement in ∆VAS Leg (β = -1.53, P = 0.034). Multiple preoperative opioid prescribers correlated with an increase in opioid prescriptions postoperatively (β = 0.26, P = 0.014), but it did not significantly affect the amount of morphine milligram equivalents prescribed (β = -48.79, P = 0.146). A greater number of preoperative opioid prescriptions predicted worse improvements in VAS Back, VAS Leg, and Oswestry Disability Index and predicted increased postoperative opioid prescriptions, prescribers, and morphine milligram equivalents.

CONCLUSIONS

Multiple preoperative opioid prescribers predicted increased improvement in postoperative back pain, whereas preoperative involvement of a nonoperative spine provider predicted improvements in leg pain after surgery. The number of preoperative opioid prescriptions was a better metric for predicting poor postoperative outcomes and increased opioid consumption compared with the number of preoperative opioid prescribers.

Intraoperative Methadone in Next-day Discharge Outpatient Surgery: A Randomized, Double-blinded, Dose-finding Pilot Study

BACKGROUND

Contemporary perioperative practice seeks to use less intraoperative opioid, diminish postoperative pain and opioid use, and enable less postdischarge opioid prescribing. For inpatient surgery, anesthesia with intraoperative methadone, compared with short-duration opioids, results in less pain, less postoperative opioid use, and greater patient satisfaction. This pilot investigation aimed to determine single-dose intraoperative methadone feasibility for next-day discharge outpatient surgery, determine an optimally analgesic and well-tolerated dose, and explore whether methadone would result in less postoperative opioid use compared with conventional short-duration opioids.

METHODS

This double-blind, randomized, dose-escalation feasibility and pilot study in next-day discharge surgery compared intraoperative single-dose IV methadone (0.1 then 0.2, 0.25 and 0.3 mg/kg ideal body weight) versus as-needed short-duration opioid (fentanyl, hydromorphone) controls. Perioperative opioid use, pain, and side effects were assessed before discharge. Patients recorded pain, opioid use, and side effects for 30 days postoperatively using take-home diaries. Primary clinical outcome was in-hospital (intraoperative and postoperative) opioid use. Secondary outcomes were 30-day opioid consumption, pain, opioid side effects, and leftover opioid counts.

RESULTS

Median (interquartile range) intraoperative methadone doses were 6 (5 to 7), 11 (10 to 12), 14 (13 to 16), and 18 (15 to 19) mg in 0.1, 0.2, 0.25, and 0.3 mg/kg ideal body weight groups, respectively. Anesthesia with single-dose methadone and propofol or volatile anesthetic was effective. Total in-hospital opioid use (IV milligram morphine equivalents [MME]) was 25 (20 to 37), 20 (13 to 30), 27 (18 to 32), and 25 (20 to 36) mg, respectively, in patients receiving 0.1, 0.2, 0.25 and 0.3 mg/kg methadone, compared to 46 (33 to 59) mg in short-duration opioid controls. Opioid-related side effects were not numerically different. Home pain and opioid use were numerically lower in patients receiving methadone.

CONCLUSIONS

The most effective and well-tolerated single intraoperative induction dose of methadone for next-day discharge surgery was 0.25 mg/kg ideal body weight (median, 14 mg). Single-dose intraoperative methadone was analgesic and opioid-sparing in next-day discharge outpatient surgery.

EDITOR’S PERSPECTIVE

Perioperative Analgesia in Spine Surgery: A Review of Current Data Supporting Future Direction

This Clinical Research discusses the diverse nature of spine surgery procedures and the use of multimodal analgesia within enhanced recovery after surgery (ERAS) protocols to improve patient outcomes. Spine surgeries range from minor decompressions to extensive tumor resections, performed by neurosurgeons or orthopedic spine surgeons on adults and children. To manage perioperative pain effectively, various methods have been employed, including multimodal analgesia within ERAS protocols. Incorporating ERAS protocols into spine surgery has shown benefits such as reduced pain scores, decreased opioid use, shorter hospital stays, and improved functionality. ERAS protocols help to enhance patient outcomes, focusing on deconstructing these protocols for surgeons and anesthesiologists.

Standardized Opioid Counseling Is Underperformed Before and After Anterior Cruciate Ligament Reconstruction

PURPOSE

To characterize contemporary pain management strategies after anterior cruciate ligament reconstruction (ACLR) within the US and international orthopaedic community.

METHODS

This was a cross-sectional survey-based study disseminated to a consortium of expert orthopaedic surgeons in the management of anterior cruciate ligament injuries. The survey was a 27-question, multiple choice-style questionnaire with question topics ranging from demographic characteristics and practice characteristics to surgeon-specific pain management strategies in the postoperative period after ACLR. Specific topics of interest included the use of preoperative opioid education and/or counseling sessions, implementation of standardized pain management regimens, use of pain tracking systems, and use of any adjunct non-narcotic analgesic modalities.

RESULTS

A total of 34 completed surveys were collected, representing a 73.9% response rate. Over 85% of respondents reported prescribing opioids as a standardized postoperative regimen after ACLR. Surgeons reported prescribing 5- to 10-mg doses, with the tablet count ranging anywhere from fewer than 10 tablets to more than 20 tablets, often instructing their patients to stop opioid use 2 to 4 days postoperatively. Prescribed dosages remained stable or decreased over the past 6 months with increased use of non-narcotic adjuncts. Only one-third of respondents reported using standardized preoperative opioid counseling, with even fewer discussing postoperative discontinuation protocols.

CONCLUSIONS

Over 85% of respondents prescribe opioids as a standardized postoperative regimen after ACLR, with only 15% providing non-narcotic pain regimens. However, prescribed dosages have remained stable or decreased over the past 6 months with increased use of non-narcotic adjuncts. Only one-third of respondents use standardized preoperative opioid counseling, with even fewer discussing postoperative discontinuation protocols.

CLINICAL RELEVANCE

The ongoing opioid epidemic has created an urgent need to identify the most effective pain management strategies after orthopaedic procedures, especially ACLR. This study provides important information about current pain management practices for patients who have undergone ACLR.

Pain and Opioid Consumption After Laparoscopic Versus Open Gastrectomy for Gastric Cancer: A Secondary Analysis of a Multicenter Randomized Clinical Trial (LOGICA-Trial)

BACKGROUND

Laparoscopic gastrectomy could reduce pain and opioid consumption, compared to open gastrectomy. However, it is difficult to judge the clinical relevance of this reduction, since these outcomes are reported in few randomized trials and in limited detail.

METHODS

This secondary analysis of a multicenter randomized trial compared laparoscopic versus open gastrectomy for resectable gastric adenocarcinoma (cT1-4aN0-3bM0). Postoperative pain was analyzed by opioid consumption in oral morphine equivalents (OME, mg/day) at postoperative day (POD) 1-5, WHO analgesic steps, and Numeric Rating Scales (NRS, 0-10) at POD 1-10 and discharge. Regression and mixed model analyses were performed, with and without correction for epidural analgesia.

RESULTS

Between 2015 and 2018, 115 patients in the laparoscopic group and 110 in the open group underwent surgery. Some 16 patients (14%) in the laparoscopic group and 73 patients (66%) in the open group received epidural analgesia. At POD 1-3, mean opioid consumption was 131, 118, and 53 mg OME lower in the laparoscopic group, compared to the open group, respectively (all p < 0.001). After correcting for epidural analgesia, these differences remained significant at POD 1-2 (47 mg OME, p = 0.002 and 69 mg OME, p < 0.001, respectively). At discharge, 27% of patients in the laparoscopic group and 43% patients in the open group used oral opioids (p = 0.006). Mean highest daily pain scores were between 2 and 4 at all PODs, < 2 at discharge, and did not relevantly differ between treatment arms.

CONCLUSION

In this multicenter randomized trial, postoperative pain was comparable between laparoscopic and open gastrectomy. After laparoscopic gastrectomy, this was generally achieved without epidural analgesia and with fewer opioids.

TRIAL REGISTRATION

NCT02248519.

Overuse of the psychoactive analgesics' opioids and gabapentinoid drugs in patients having surgery for nerve entrapment disorders

Knowledge about risks for overuse of psychoactive analgesics in patients having primary surgery for carpal tunnel syndrome (CTS) or ulnar nerve entrapment (UNE), or both, is limited. We investigated if patients with those nerve entrapment disorders have a higher risk of overuse of psychoactive analgesics (i.e., opioids and gabapentinoid drugs) before, after, and both before and after surgery than observed in the general population after accounting for demographical and socioeconomic factors. Using a large record linkage database, we analysed 5,966,444 individuals (25-80 years), residing in Sweden December 31st, 2010-2014, of which 31,380 underwent surgery 2011-2013 for CTS, UNE, or both, applying logistic regression to estimate relative risk (RR) and 95% confidence interval (CI). Overall, overuse of the psychoactive analgesics was low in the general population. Compared to those individuals, unadjusted RR (95% CI) of overuse ranged in patients between 2.77 (2.57-3.00) with CTS after surgery and 6.21 (4.27-9.02) with both UNE and CTS after surgery. These risks were only slightly reduced after adjustment for demographical and socioeconomic factors. Patients undergoing surgery for CTS, UNE, or both, have a high risk of overuse of psychoactive analgesics before, after, and both before and after surgery.

Incidence of opioid use and early postoperative pain intensity after primary unilateral inguinal hernia repair at a single-center specialty hospital

PURPOSE

This research examined opioid use, pain intensity, and pain management after primary unilateral inguinal hernia repair (PUIHR) at a single-center specialty hospital.

METHODS

After research, ethics board approval, and informed consent, pain scores (0-10 numerical rating scale [NRS]) were obtained from survey-based questionnaires administered at the pre- and 3-day postoperative timepoints. Descriptive results are presented as frequency, mean, standard deviation, range, median, and interquartile ranges, as appropriate. Significance tests were conducted to compare participants who did and did not receive opioids after surgery. p-value <0.05 is considered statistically significant. As the standard of care, participants received nonopioid multimodal analgesia (acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs)) and opioids, when necessary.

RESULTS

A total of 414 and 331 participants completed the pre- and 3-day postoperative questionnaires, respectively. Out of the 414 participants, 38 (9.2%) received opioids during the postoperative stay. There was no significant difference between pain frequency or mean preoperative NRS pain intensity scores of those who did and did not receive opioids. Mean NRS pain intensity scores on day 3 after surgery were significantly higher for participants who received opioids (3.15±2.08) than those who did not (2.19±1.95), p=0.005.

CONCLUSION

Most participants did not receive opioids after PUIHR and had lower mean postoperative NRS pain intensity scores compared to those who did, most likely reflecting the need for opioids among the latter. Opioids were discontinued by day 3 for all participants who received them. Therefore, for most patients undergoing PUIHR, effective pain control can be achieved with nonopioid multimodal analgesia in the early postoperative period.

An individualised tapering protocol reduces opioid use 1 year after spine surgery: A randomised controlled trial of patients with preoperative opioid use

BACKGROUND

Persistent opioid use following surgery is common especially in patients with preoperative opioid use. This study aims to determine the long-term effect of an individualised opioid tapering plan versus standard of care in patients with a preoperative opioid use undergoing spine surgery at Aarhus University Hospital, Denmark.

METHODS

This is the 1-year follow-up of a prospective, single-centre, randomised trial of 110 patients who underwent elective spine surgery for degenerative disease. The intervention was an individualised tapering plan at discharge and telephone counselling 1 week after discharge, compared to standard of care. Postoperative outcomes after 1 year include opioid use, reasons for opioid use and pain intensity.

RESULTS

The overall response rate to the 1-year follow-up questionnaire was 94% (intervention group 52/55 patients and control group 51/55 patients). Forty-two patients (proportion = 0.81, 95% CI 0.67-0.89) in the intervention group compared to 31 (0.61, 95% CI 0.47-0.73; p = .026) patients in the control group succeeded in tapering to zero 1 year after discharge (p = .026). One patient (0.02, 95% CI 0.01-0.13) in the intervention group compared to seven patients (0.14, 95% CI 0.07-0.26) in the control group were unable to taper to their preoperative dose 1 year after discharge (p = .025). Back/neck and radicular pain intensity was similar between study groups.

CONCLUSION

These results suggest that an individualised tapering plan at discharge combined with telephone counselling 1 week after discharge can reduce opioid use 1 year after spine surgery.

Comparison of Different Modeling Approaches for Prescription Opioid Use and Its Association With Adverse Events

Previous research linking opioid prescribing to adverse drug events has failed to properly account for the time-varying nature of opioid exposure. This study aimed to explore how the risk of opioid-related emergency department visits, readmissions, or deaths (composite outcome) varies with opioid dose and duration, comparing different novel modeling techniques. A prospective cohort of 1,511 hospitalized patients discharged from 2 McGill-affiliated hospitals in Montreal, 2014-2016, was followed from the first postdischarge opioid dispensation until 1 year after discharge. Marginal structural Cox proportional hazards models and their flexible extensions were used to explore the association between time-varying opioid use and the composite outcome. Weighted cumulative exposure models assessed cumulative effects of past use and explored how its impact depends on the recency of exposure. The patient mean age was 69.6 (standard deviation = 14.9) years; 57.7% were male. In marginal structural model analyses, current opioid use was associated with a 71% increase in the hazard of opioid-related adverse events (adjusted hazard ratio = 1.71, 95% confidence interval: 1.21, 2.43). The weighted cumulative exposure results suggested that the risk cumulates over the previous 50 days of opioid consumption. Flexible modeling techniques helped assess how the risk of opioid-related adverse events may be associated with time-varying opioid exposures while accounting for nonlinear relationships and the recency of past use.

Opioid prescriptions and patients' health services utilization and cost before and during the COVID-19 pandemic: an exploratory population-based administrative data analysis

The objective was to explore percentages of the population treated with prescribed opioids and costs of opioid-related hospitalizations and emergency department (ED) visits among individuals treated with prescription opioids and costs of all opioid-related hospitalizations and ED visits in the province (i.e., provincial costs) before and during the coronavirus disease 2019 (COVID-19) pandemic in Alberta, Canada. In administrative data, we identified individuals treated with prescription opioids and opioid-related hospitalizations and ED visits among those individuals and among all individuals in the province between 2015/16 and 2021/22 fiscal years. Services used were counted on an item-by-item basis and costed using case-mix approaches. Annually, from 9.98% (2020/21-2021/22) to 14.52% (2017/18) of the provincial population was treated with prescription opioids. Between 2015/16 and 2021/22, annual costs of opioid-related hospitalizations and ED visits among individuals treated with prescription opioids were ∼$5 and ∼$2 million, respectively. In 2020/21-2021/22, the provincial costs of opioid-related hospitalizations (∼$14 million) and ED visits (∼$7.0 million) were almost twice the costs observed in 2015/16 and immediately before the pandemic (2019/20). Our findings suggest that increases in the opioid-related utilization of inpatient and ED services between 2015/16 and 2021/22, including the drastic increases observed during the COVID-19 pandemic, were likely driven by unregulated substances.

Multimodal Analgesia for Paediatric Patients Undergoing Lower Limb Reconstruction with External Fixators: A Prospective Case Series of Post-operative Pain and Functional Goals

Aim

Limb reconstruction with external fixators requires appropriate pain management to promote effective analgesia and healing while minimising adverse events of the analgesic technique used. The objective of this prospective case series was to evaluate a multimodal analgesia regimen designed to reduce opioid requirements and hence reduce the opioid-related side effect profile.

Materials and methods

A prospective cohort of patients undergoing lower limb reconstruction surgery (LRS) were managed through an evidence-informed multimodal analgesia guideline (MMAG), including acetaminophen, pregabalin, dexmedetomidine, IV lidocaine, and opioids. Outcome measures included intraoperative and post-operative opioid administration, post-operative pain scores, time to achieve mobilisation milestones, and post-operative complications. Surveys were conducted to obtain patient reported experiences.

Results

26 patients were included in this prospective case series. 110.59 (84.29, 162.13) (median, interquartile range) µg/kg/hr intraoperative IV morphine equivalent opioids were administered. In the first 48 hours post-operatively, patients received 11.49 (6.41, 19.35) µg/kg/hr of IV morphine equivalent dose. Median level of pain (0-10) in the first 48 post-operative hours was 2 (1, 2). Patients achieved mobilisation. And 19/20 patients surveyed reported 'yes' to having effective pain management; 17/20 patients had no unwanted side effects associated with analgesia medications. There were no cases of compartment syndrome.

Conclusion

This multimodal analgesia regime applied to patients undergoing lower LRS with external fixators demonstrates the feasibility of this analgesic regimen which revealed effective pain control, early mobilisation, with minimal side effects, but warrants further study.

Clinical significance

This study provides valuable evidence that this standardised multimodal anaesthesia and analgesia regimen is feasible, offers adequate post-operative comfort and encourages early mobilization while minimising opioid use and adverse events in a paediatric LRS population at our institution.

How to cite this article

Wang AWT, Chhina H, Cooper A. Multimodal Analgesia for Paediatric Patients Undergoing Lower Limb Reconstruction with External Fixators: A Prospective Case Series of Post-operative Pain and Functional Goals. Strategies Trauma Limb Reconstr 2023;18(3):140-147.

Opioid Overprescription and Underprescription to Patients After Otolaryngology-Head and Neck Surgery

This cohort study examines the extent of mismatched opioid prescribing between hospitalization and discharge after otolaryngology–head and neck surgery.

EEG-derived pain threshold index-guided versus standard care during propofol-remifentanil anesthesia: A randomized controlled trial

Purpose

The pain threshold index (PTI), a novel index of nociception based on spontaneous EEG wavelet analysis, has been reported to provide reliable accuracy for predicting postoperative pain and hemodynamic reactivity. The present study is aimed to investigate whether PTI-guided analgesia reduces the pain intensity and rate of remedial analgesia in the post-anesthesia care unit (PACU).

Methods

A total of 122 females undergoing elective gynecologic surgeries had been randomized to receive either PTI-guided analgesia (PTI group) or standard clinical care (control group). Remifentanil administration in the PTI group was guided by PTI to maintain the value between 40 and 65, while that in the control group was guided by hemodynamic changes. The primary outcome was remedial analgesia rate in the PACU. The postoperative pain scores, intraoperative remifentanil requirements, opioid-related adverse events and perioperative serum stress hormone concentrations between the two groups were also compared.

Findings

It was found that 23 of 58 patients (40%) in the control group and 8 of 58 patients (14%) in the PTI group needed remedial analgesia. The relative risk of receiving remedial analgesia was 2.88 (95% CI, 1.40-5.89, P = 0.002) in the control group. Sufentanil consumption in the PACU (μg) was lower in the PTI group (P = 0.002) than in the control group. Remifentanil and propofol consumption, opioid-related adverse events between these two groups were comparable.

Implications

PTI-guided analgesia during gynaecologic operations resulted in 25.87% less remedial analgesia. However, studies with different PTI thresholds and larger, more diverse populations should be conducted to further demonstrate the clinical effectiveness of PTI.

Process, structural, and outcome quality indicators to support perioperative opioid stewardship: a rapid review

Opioids are effective analgesics but can cause harm. Opioid stewardship is key to ensuring that opioids are used effectively and safely. There is no agreed set of quality indicators relating to the use of opioids perioperatively. This work is part of the Yorkshire Cancer Research Bowel Cancer Quality Improvement programme and aims to develop useful quality indicators for the improvement of care and patient outcomes at all stages of the perioperative journey.A rapid review was performed to identify original research and reviews in which quality indicators for perioperative opioid use are described. A data tool was developed to enable reliable and reproducible extraction of opioid quality indicators.A review of 628 abstracts and 118 full-text publications was undertaken. Opioid quality indicators were identified from 47 full-text publications. In total, 128 structure, process and outcome quality indicators were extracted. Duplicates were merged, with the final extraction of 24 discrete indicators. These indicators are based on five topics: patient education, clinician education, pre-operative optimization, procedure, and patient-specific prescribing and de-prescribing and opioid-related adverse drug events.The quality indicators are presented as a toolkit to contribute to practical opioid stewardship. Process indicators were most commonly identified and contribute most to quality improvement. Fewer quality indicators relating to intraoperative and immediate recovery stages of the patient journey were identified. An expert clinician panel will be convened to agree which of the quality indicators identified will be most valuable in our region for the management of patients undergoing surgery for bowel cancer.

Use of Wearable Sensor Device and Mobile Application for Objective Assessment of Pain in Post-surgical Patients: A Preliminary Study

Effective post-operative pain management requires an accurate and frequent assessment of the pain experienced by the patients. The current gold-standard of pain assessment is through patient self-evaluation (e.g., numeric rating scale, NRS) which is subjective, prone to recall-bias, and does not provide comprehensive information of the pain intensity and its trends. We conducted a study to explore the potential of wearable biosensors and machine learning-based analysis of physiological parameters to estimate the pain intensity. The results from our study of post-operative knee surgery patients monitored over a period of 30 days demonstrate the feasibility of the system in ambulatory setting, with a substantial agreement (Cohen's Kappa = 0.70, 95% CI 0.68-0.72) between the pain intensity estimation and the patient reported numerical rating scale. Therefore, the wearable biosensors coupled with the machine learning-derived pain estimation are capable of remotely assessing the pain intensity.

Effect of Peripheral Magnetic Stimulation on Acute and Chronic Pain After Surgery: A Systematic Review and Meta-Analysis

Peripheral magnetic stimulation (PMS) is a potentially promising modality to help manage postoperative pain. We systematically reviewed the effect of PMS on acute and chronic postoperative pain. MEDLINE, Cochrane CENTRAL, EMBASE, ProQuest Dissertations, and clinical trials.gov were searched from inception until May 2021. We included studies of any study design that included patients ≥18 years of age undergoing any type of surgery that administered PMS within the perioperative period and evaluated postoperative pain. Seventeen randomized controlled trials and 1 nonrandomized clinical trial were included into the review. Thirteen out of the 18 studies found a positive effect with PMS on postoperative pain scores. In our meta-analysis, peripheral magnetic stimulation was more efficacious than sham or no intervention within the first 7 postoperative days (mean difference [MD] -1.64 on a 0 to 10 numerical rating score, 95% confidence interval [CI] -2.08 to -1.20, I2 = 77%, 6 studies, 231 patients). This was also true at 1 and 2 months after surgery (MD -1.82, 95% CI -2.48 to -1.17, I2 = 0%, 3 studies, 104 patients; and MD -1.96, 95% CI -3.67 to -.26, I2 = 84%, 3 studies, 104 patients, respectively). A difference was not seen with persistent pain at 6 and 12-months after surgery, acute postoperative opioid consumption, or adverse events between groups. Results are limited by heterogeneity and generally low-quality studies, as well as low or very low quality of evidence. High-quality and adequately blinded trials are needed to definitively confirm the benefits of peripheral magnetic stimulation administered in the perioperative period. PERSPECTIVE: This review evaluates the efficacy and safety of PMS on postoperative pain. The results help elucidate PMS' role in postoperative pain management and identify gaps where more research is required.

No significant difference in risk of prolonged opioid use following outpatient versus inpatient total shoulder arthroplasty: A propensity matched analysis

Background

The purpose of this investigation was to compare rates of filled opioid prescriptions and prolonged opioid use in opioid naïve patients undergoing total shoulder arthroplasty (TSA) in inpatient versus outpatient settings.

Methods

A retrospective cohort study was conducted using a national insurance claims database. Inpatient and outpatient cohorts were created by identifying continuously enrolled, opioid naïve TSA patients. A greedy nearest-neighbor algorithm was used to match baseline demographic characteristics between cohorts with a 1:1 inpatient to outpatient ratio to compare the primary outcomes of filled opioid prescriptions and prolonged opioid use following surgery between cohorts.

Results

A total of 11,703 opioid naïve patients (mean age 72.5 ± 8.5 years, 54.5% female, 87.6% inpatient) were included for analysis. After propensity score matching (n = 1447 inpatients; n = 1447 outpatients), outpatient TSA patients were significantly more likely to fill an opioid prescription in the perioperative window compared to inpatients (82.9% versus 71.5%, p < 0.001). No significant differences in prolonged opioid use were detected (5.74% inpatient versus 6.77% outpatient; p = 0.25).

Conclusions

Outpatient TSA patients were more likely to fill opioid prescriptions compared to inpatient TSA patients. The quantity of opioids prescribed and rates of prolonged opioid use were similar between the cohorts.

Level of evidence

Therapeutic Level III.

Modulation of the Inflammatory Response by Pre-emptive Administration of IMT504 Reduces Postoperative Pain in Rats and has Opioid-Sparing Effects

Despite the available knowledge on underlying mechanisms and the development of several therapeutic strategies, optimal management of postoperative pain remains challenging. This preclinical study hypothesizes that, by promoting an anti-inflammatory scenario, pre-emptive administration of IMT504, a noncoding, non-CpG oligodeoxynucleotide with immune modulating properties, will reduce postincisional pain, also facilitating therapeutic opioid-sparing. Male adult Sprague-Dawley rats with unilateral hindpaw skin-muscle incision received pre-emptive (48 and 24 hours prior to surgery) or postoperative (6 hours after surgery) subcutaneous vehicle (saline) or IMT504. Various groups of rats were prepared for pain-like behavior analyses, including subgroups receiving morphine or naloxone, as well as for flow-cytometry or quantitative RT-PCR analyses of the spleen and hindpaws (for analysis of inflammatory phenotype). Compared to vehicle-treated rats, pre-emptive IMT504 significantly reduced mechanical allodynia by 6 hours after surgery, and accelerated recovery of basal responses from 72 hours after surgery and onwards. Cold allodynia was also reduced by IMT504. Postoperative administration of IMT504 resulted in similar positive effects on pain-like behavior. In IMT504-treated rats, 3 mg/kg morphine resulted in comparable blockade of mechanical allodynia as observed in vehicle-treated rats receiving 10 mg/kg morphine. IMT504 significantly increased hindpaw infiltration of mesenchymal stem cells, CD4+T and B cells, and caused upregulated or downregulated transcript expressions of interleukin-10 and interleukin-1β, respectively. Also, IMT504 treatment targeted the spleen, with upregulated or downregulated transcript expressions, 6 hours after incision, of interleukin-10 and interleukin-1β, respectively. Altogether, pre-emptive or postoperative IMT504 provides protection against postincisional pain, through participation of significant immunomodulatory actions, and exhibiting opioid-sparing effects. PERSPECTIVE: This preclinical study introduces the noncoding non-CpG oligodeoxynucleotide IMT504 as a novel modulator of postoperative pain and underlying inflammatory events. The opioid-sparing effects observed for IMT504 appear as a key feature that could contribute, in the future, to reducing opioid-related adverse events in patients undergoing surgical intervention.

Surgical Trainee Perspectives on the Opioid Crisis: The Influence of Explicit and Hidden Curricula

OBJECTIVE

In order to effectively create and implement an educational program to improve opioid prescribing practices, it is important to first consider the unique perspectives of residents on the frontlines of the opioid epidemic. We sought to better understand resident perspectives on opioid prescribing, current practices in pain management, and opioid education as a needs assessment for designing future educational interventions.

DESIGN

This is a qualitative study using focus groups of surgical residents at 4 different institutions.

SETTING

We conducted focus groups using a semistructured interview guide in person or over video conferencing. The residency programs selected for participation represent a broad geographic range and varying residency sizes.

PARTICIPANTS

We used purposeful sampling to recruit general surgery residents from the University of Utah, University of Wisconsin, Dartmouth-Hitchcock Medical Center, and the University of Alabama at Birmingham. All general surgery residents at these locations were eligible for inclusion. Participants were assigned to focus groups by residency site and their status as junior (PGY-2, PGY-3) or senior resident (PGY-4, PGY-5).

RESULTS

We completed 8 focus groups with a total of 35 residents included. We identified 4 main themes. First, residents relied on clinical and nonclinical factors when making decisions about opioid prescribing. However, hidden curricula based on unique institutional cultures and attending preferences heavily influenced residents' prescribing practices. Second, residents acknowledged that stigma and biases towards certain patient groups influenced opioid prescribing practices. Third, residents encountered barriers within their health systems to evidence-based opioid prescribing. Fourth, residents did not routinely receive formal education on pain management or opioid prescribing. Residents recommended several interventions to improve the current state of opioid prescribing, including standardized prescribing guidelines, improved patient education, and formal training during the first year of residency.

CONCLUSIONS

Our study highlighted several areas of opioid prescribing that can be improved upon through educational interventions. These findings can be used to develop programs aimed at improving residents' opioid prescribing practices, both during and after training, and ultimately the safe care of surgical patients.

ETHICS STATEMENT

This project was approved by the University of Utah Institutional Review Board, ID # 00118491. All participants provided written informed consent.

Association of Reported Nonsteroidal Anti-Inflammatory Drug (NSAID) Adverse Drug Reactions With Opioid Prescribing After Total Joint Arthroplasty

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are indicated for postoperative pain management, but use may be precluded by the report of adverse drug reactions (ADRs). The effect of NSAID ADR labeling on opioid prescribing after total joint arthroplasty (TJA) is unknown.

OBJECTIVE

To assess the association between NSAID ADRs and postoperative opioid prescribing after TJA, a common surgical procedure.

METHODS

We performed a retrospective cohort study of adults who underwent total joint (knee or hip) replacement in a single hospital network between April, 1, 2016, and December 31, 2019. Demographic information, clinical and surgical characteristics, and prescription data were obtained from the electronic health record. We studied the association between reported NSAID ADRs and postoperative opioid prescribing in a propensity score-matched sample over 1 year of follow-up.

RESULTS

NSAID ADRs were reported by 9.6% of the entire cohort (n = 584/6091). NSAID ADR was associated with 41% higher odds of receipt of opioid prescriptions at 181 to 365 days after hospital discharge (95% confidence interval: 13%-75%) in a propensity score-matched sample. Over 98% of individuals received an opioid prescription at the time of hospital discharge, with no difference in overall median opioid dose prescribed by NSAID ADR status. However, more patients with NSAID ADRs (7.6% vs 4.7%) received cumulative opioid doses ≥ 750 morphine milligram equivalents (MME) at discharge (P = .004).

CONCLUSION

Reported NSAID ADR was associated with increased risk for prolonged receipt of opioids at 181 to 365 days postoperatively. Patients with NSAID ADRs more frequently received cumulative opioid doses ≥ 750 MME at discharge after TJA. Clarification and evaluation of reported NSAID ADRs may be particularly beneficial for surgical patients at high risk for prolonged receipt of opioids.

Dexamethasone and persistent wound pain: a prespecified analysis of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial

BACKGROUND

Dexamethasone is commonly administered intraoperatively to prevent postoperative nausea and vomiting and is believed to have analgesic properties. It is unknown whether it has an impact on chronic wound pain.

METHODS

In this prespecified embedded superiority substudy of the randomised PADDI trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and were followed up for 6 months postoperatively. The primary outcome was the incidence of pain in the surgical wound at 6 months. Secondary outcomes included acute postoperative pain and correlates of chronic postsurgical pain.

RESULTS

We included 8478 participants in the modified intention-to-treat population (4258 in the dexamethasone group and 4220 in the matched placebo group). The primary outcome occurred in 491 subjects (11.5%) in the dexamethasone arm and 404 (9.6%) subjects in the placebo arm (relative risk 1.2, 95% confidence interval 1.06-1.41, P=0.003). Maximum pain scores at rest and on movement in the first 3 postoperative days were lower in the dexamethasone group compared with the control group {median 5 (inter-quartile range [IQR] 3.0-8.0) vs 6 (IQR 3.0-8.0) and median 7 (IQR 5.0-9.0) vs 8 (IQR 6.0-9.0), P<0.001 for both}. Severity of postoperative pain was not predictive of chronic postsurgical pain. The severity of chronic postsurgical pain and the frequency of neuropathic features did not differ between treatment groups.

CONCLUSION

Administration of dexamethasone 8 mg i.v. was associated with an increase in the risk of pain in the surgical wound 6 months after surgery.

CLINICAL TRIAL REGISTRATION

ACTRN12614001226695.

Managing opioid waste, cost, and opportunity for drug diversion in the emergency department

INTRODUCTION

Management of pain is a component of 80% of all emergency department (ED) visits, and intravenous (IV) opioids are most commonly used to treat moderate to severe pain. Since the dose of stock vials is rarely purchased based on provider ordering patterns, there is often a discrepancy between ordered doses and the dose of the stock vial, leading to waste. Here, waste is defined as the difference between the dose of the stock vials used to fill an order and the ordered dose. Drug waste is problematic as it increases the chance of administering the incorrect dose, it is a source of lost revenue, and in the context of opioids, it increases the opportunity for drug diversion. In this study, we sought to utilize real-world data to describe the magnitude of morphine and hydromorphone waste in the studied EDs. We also applied scenario analyses based on provider ordering patterns to simulate the effects of cost versus opioid waste minimization when making purchasing decisions for the dose of stock vial of each opioid.

METHODS

This was an observational analysis of IV morphine and hydromorphone orders across three EDs within a health care system between December 1, 2014 and November 30, 2015. In the primary analysis we measured total waste and cost of all ordered hydromorphone and morphine, and we created logistic regression models for each opioid to estimate the odds that a given ordered dose would create waste. In the secondary scenario analysis we determined the total waste created and total cost to satisfy all written orders for both opioids with respect to prioritizing minimizing waste versus cost.

RESULTS

Among a total of 34,465 IV opioid orders, 7866 (35%) of morphine orders created 21,767 mg of waste, and 10,015 (85%) of hydromorphone orders created 11,689 mg of waste. Larger dose orders were associated with a smaller likelihood of waste in both morphine and hydromorphone due to the doses of stock vials available. In the waste optimization scenario, relative to the base scenario, total waste, which included waste from both morphine and hydromorphone, was reduced by 97% and cost was reduced by 11%. In the cost optimization scenario, cost was reduced by 28% but waste increased by 22%.

CONCLUSION

As hospitals continue to seek strategies to reduce costs and mitigate the harms of opioid diversion amidst the opioid epidemic, this study shows that optimizing the dose of the stock vial to minimize waste using provider ordering patterns, could mitigate risk while also reducing cost. Limitations included the use of data from EDs within a single health system, drug shortages that affected stock vial availability, and finally, the actual cost of stock vials, used for cost calculations, can differ based on a variety of factors.

High-risk Opioid Prescribing Associated with Postoperative New Persistent Opioid Use in Adolescents and Young Adults

OBJECTIVE

In this study, we explored which postoperative opioid prescribing practices were associated with persistent opioid use among adolescents and young adults.

BACKGROUND

Approximately 5% of adolescents and young adults develop postoperative new persistent opioid use. The impact of physician prescribing practices on persistent use among young patients is unknown.

METHODS

We identified opioid-naïve patients aged 13 to 21 who underwent 1 of 13 procedures (2008-2016) and filled a perioperative opioid prescription using commercial insurance claims (Optum Deidentified Clinformatics Data Mart Database). Persistent use was defined as ≥ 1 opioid prescription fill 91 to 180 days after surgery. High-risk opioid prescribing included overlapping opioid prescriptions, co-prescribed benzodiazepines, high daily prescribed dosage, long-acting formulations, and multiple prescribers. Logistic regression modeled persistent use as a function of exposure to high-risk prescribing, adjusted for patient demographics, procedure, and comorbidities.

RESULTS

High-risk opioid prescribing practices increased from 34.9% to 43.5% over the study period; the largest increase was in co-prescribed benzodiazepines (24.1%-33.4%). High-risk opioid prescribing was associated with persistent use (aOR 1.235 [1.12,1.36]). Receipt of prescriptions from multiple opioid prescribers was individually associated with persistent use (aOR 1.288 [1.16,1.44]). The majority of opioid prescriptions to patients with persistent use beyond the postoperative period were from nonsurgical prescribers (79.6%).

CONCLUSIONS

High-risk opioid prescribing practices, particularly receiving prescriptions from multiple prescribers across specialties, were associated with a significant increase in adolescent and young adult patients' risk of persistent opioid use. Prescription drug monitoring programs may help identify young patients at risk of persistent opioid use.

Surgeon Postoperative Opioid Prescribing Intensity and Risk of Persistent Opioid Use Among Opioid-naive Adult Patients: A Population-based Cohort Study

OBJECTIVE

The aim of this study was to determine the relationship between surgeon opioid prescribing intensity and subsequent persistent opioid use among patients undergoing surgery.

SUMMARY BACKGROUND DATA

The extent to which different postoperative prescribing practices lead to persistent opioid use among surgical patients is poorly understood.

METHODS

Retrospective population-based cohort study assessing opioid-naive adults who underwent 1 of 4 common surgeries. For each surgical procedure, the surgeons' opioid prescribing intensity was categorized into quartiles based on the median daily dose of morphine equivalents of opioids dispensed within 7 days of the surgical visit for all the surgeons' patients. The primary outcome was persistent opioid use in the year after surgery, defined as 180 days or more of opioids supplied within the year after the index date excluding prescriptions filled within 30 days of the index date. Secondary outcomes included a refill for an opioid within 30 days and emergency department visits and hospitalizations within 1 year.

RESULTS

Among 112,744 surgical patients, patients with surgeons in the highest intensity quartile (Q4) were more likely to fill an opioid prescription within 7 days after surgery compared with those in the lowest quartile (Q1) (83.3% Q4 vs 65.4% Q1). In the primary analysis, the incidence of persistent opioid use in the year after surgery was rare in both highest and lowest quartiles (0.3% Q4 vs 0.3% Q1), adjusted odds ratio (AOR) of 1.18, 95% CI 0.83-1.66). However, multiple analyses using stricter definitions of persistent use that included the requirement of a prescription filled within 7 days of discharge after surgery showed a significant association with surgeon quartile (up to an AOR 1.36, 95% CI 1.25, 1.47). Patients in Q4 were more likely to refill a prescription within 30 days (4.8% Q4 vs 4.0% Q1, AOR 1.14, 95% CI 1.04-1.24).

CONCLUSIONS

Surgeons' overall prescribing practices may contribute to persistent opioid use and represent a target for quality improvement. However, the association was highly sensitive to the definition of persistent use used.

Ultrasound-Guided Quadratus Lumborum Block at the Lateral Supra-Arcuate Ligament versus Subcostal Transversus Abdominis Plane Block for Postoperative Analgesia Following Open Hepatectomy: A Randomized Controlled Trial

Purpose

Many studies confirmed that several approaches of quadratus lumborum block (QLB) were superior to transversus abdominis plane block (TAPB) in reducing opioid consumption during postoperative period. As a new QLB approach at the lateral supra-arcuate ligament (QLB-LSAL), the analgesic efficacy and safety in patients undergoing open hepatectomy are still unknown. This study aims to compare postoperative analgesia between the blocks in open hepatectomy.

Patients and Methods

Sixty-two patients undergoing open hepatectomy were enrolled and randomly allocated into the QLB-LSAL group (group Q) and the subcostal TAPB group (group T). Preoperatively, patients received ultrasound-guided bilateral QLB-LSAL or subcostal TAPB with injection of 0.5% ropivacaine (a total volume of 40 mL). The primary outcome was cumulative total morphine equivalent consumption in the first postoperative 24 h. Other outcomes included numerical rating scale (NRS) scores at rest and coughing, cumulative total morphine equivalent consumption at 2, 6, 12, 48 h, Quality of Recovery-15 (QoR-15) scores, time to first patient-controlled intravenous analgesia (PCIA) request, time to first ambulation and adverse effects.

Results

The cumulative total morphine equivalent consumption in group Q was decreased significantly at all postoperative time points (P < 0.01). The postoperative NRS scores at rest and coughing in group Q were lower than those in group T at all postoperative time points except 48 h (P < 0.05). A significant increase was also observed in the QoR-15 scores among patients in group Q. Time to first PCIA request was significantly prolonged in group Q than in group T, and time to first ambulation was shortened. Adverse effects showed no statistical significance between the two groups.

Conclusion

Compared with subcostal TAPB, preoperative bilateral QLB-LSAL provided superior analgesic properties and promoted early postoperative recovery quality in patients undergoing open hepatectomy.

Trial Registration

China Clinical Trials Registration Center (http://www.chictr.org.cn) ChiCTR2200063291, 3/9/2022.

Perioperative opioids: a narrative review contextualising new avenues to improve prescribing

Opioids have dominated the management of perioperative pain in recent decades with higher doses than ever before used in some circumstances. Through the expanding use of opioids, growing research has highlighted their associated side-effects and the intertwined phenomena of acute withdrawal syndrome, opioid tolerance, and opioid-induced hyperalgesia. With multiple clinical guidelines now endorsing multimodal analgesia, a diverse array of opioid-sparing agents emerges and has been studied to variable degrees, including techniques of opioid-free anaesthesia. It remains unclear to what extent such methods should be adopted, yet current evidence does suggest dependence on opioids as the primary perioperative analgesic might not meet the principles of 'rational prescribing' as described by Maxwell. In this narrative review we describe how, using current evidence, a patient-centred rational-prescribing approach can be applied to opioids in the perioperative period. To contextualise this approach, we discuss the historical adoption of opioids in anaesthesia, our growing understanding of associated side-effects and emerging strategies of opioid-sparing and opioid-free anaesthesia. We discuss avenues and challenges for improving opioid prescribing to limit persistent postoperative opioid use and how these may be incorporated into a rational-prescribing approach.

Nociception Level Index-Guided Intraoperative Analgesia for Improved Postoperative Recovery: A Randomized Trial

BACKGROUND

Nociception is the physiological response to nociceptive stimuli, normally experienced as pain. During general anesthesia, patients experience and respond to nociceptive stimuli by increasing blood pressure and heart rate if not controlled by preemptive analgesia. The PMD-200 system from Medasense (Ramat Gan, Israel) evaluates the balance between nociceptive stimuli and analgesia during general anesthesia and generates the nociception level (NOL) index from a single finger probe. NOL is a unitless index ranging from 0 to 100, with values exceeding 25 indicating that nociception exceeds analgesia. We aimed to demonstrate that titrating intraoperative opioid administration to keep NOL <25 optimizes intraoperative opioid dosing. Specifically, we tested the hypothesis that pain scores during the initial 60 minutes of recovery are lower in patients managed with NOL-guided fentanyl than in patients given fentanyl per clinical routine.

METHODS

We conducted a randomized, single-center trial of patients having major abdominal open and laparoscopic surgeries. Patients were randomly assigned 1:1 to intraoperative NOL-guided fentanyl administration or fentanyl given per clinical routine. The primary outcome was pain score (0-10 verbal response scale) at 10-minute intervals during the initial 60 minutes of recovery. Our secondary outcome was a measure of adequate analgesia, defined as a pain score <5, assessed separately at each interval.

RESULTS

With a planned maximum sample size of 144, the study was stopped for futility after enrolling 72 patients from November 2020 to October 2021. Thirty-five patients were assigned to NOL-guided analgesic dosing and 37 to routine care. Patients in the NOL group spent significantly less time with a NOL index >25 (median reduction [95% confidence interval {CI}] of 14 [4-25] minutes) were given nearly twice as much intraoperative fentanyl (median [quartiles] 500 [330, 780] vs 300 [200, 330] µg), and required about half as much morphine in the recovery period (3.3 [0, 8] vs 7.7 [0, 13] mg). However, in the primary outcome analysis, NOL did not reduce pain scores in the first 60 minutes after awakening, assessed in a linear mixed effects model with mean (standard error [SE]) of 4.12 (0.59) for NOL and 4.04 (0.58) for routine care, and estimated difference in means of 0.08 (-1.43, 1.58), P = .895.

CONCLUSIONS

More intraoperative fentanyl was given in NOL-guided patients, but NOL guidance did not reduce initial postoperative pain scores.

"I Prefer to Stay Away": A Qualitative Study of Patients in an Opioid-Sparing Pain Management Protocol

OBJECTIVE

The aim of this study was to explore beliefs and behaviors of opioid pain medications among patients undergoing elective surgery.

BACKGROUND

Opioid dependence after surgery is a major contributor to the ongoing opioid epidemic. Recent efforts by surgeons and health systems have sought to improve the education patients receive regarding safe opioid use after surgery; however, little is known about patients' pre-existing beliefs surrounding opioids.

METHODS

Semistructured interviews were conducted with patients who underwent 1 of 4 common elective surgical procedures at 1 institution. Patients were specifically asked about their knowledge and beliefs about opioids before surgery and their opinions of opioid-sparing recovery after surgery. Coding was conducted through iterative steps, beginning with an initial cycle of rapid analysis, followed by focused coding, and thematic analysis.

RESULTS

Twenty-one patients were interviewed. Three major themes emerged regarding patient opinions about using opioids after surgery. First, there was widespread awareness among patients about opioid medications, and preoperatively, patients had specific intentions about using opioids, often informed by this awareness. Second, patients described a spectrum of opioid related behavior which both aligned and conflicted with preoperative intentions. Third, there was tension among patients about opioid-free postoperative recovery, with patients expressing support, opposition, and emphasis on tailoring recovery to patient needs.

CONCLUSIONS

Patients undergoing common surgical procedures often arrive at their surgical encounter with strong, pre-formed opinions about opioids. Eliciting these preexisting opinions may help surgeons better counsel patients about safe opioid use after surgery.

Opioid Prescription Patterns 90 Days After Arthroscopic Rotator Cuff Repair: A 10-Year National Database Analysis

Background

Arthroscopic rotator cuff repair (ARCR) is a common procedure that typically requires opioid prescription for postoperative pain management.

Purpose

To investigate the current prescription patterns and factors influencing 90-day postoperative opioid prescription trends for opioid-naïve patients who underwent ARCR.

Study Design

Case series; Level of evidence, 4.

Methods

Opioid-naïve adult patients who underwent ARCR between January 2010 and September 2020 and had a record of opioid prescriptions during the 90-day postoperative period were identified in the PearlDiver Mariner91 national administrative database. Exclusions included patients with prior shoulder procedures, a history of chronic pain, and opioid prescription records dated earlier than 4 weeks before surgery. Covariates included age group, sex, Elixhauser Comorbidity Index, and prescriber specialty (orthopaedic or nonorthopaedic). The primary outcome-90-day postoperative morphine milligram equivalents (MMEs) prescribed per patient-was compared using univariate and multivariate regression analyses, and 90-day postoperative opioid prescription trends over the 10-year study period were analyzed with linear regression.

Results

In total, 55,345 ARCR cases were identified. The mean ± SD amount prescribed within the first 90 days was 742.4 ± 256.5 MMEs, and the median was 487.5 MMEs. Multivariate linear regression analysis predicted higher 90-day postoperative MMEs for female patients and younger patients (P < .01 for both). From 2010 to 2020, there was a 66% decrease in mean MME prescribed per patient (▵ = 660.4 MME; P < .01), with a mean reduction of 55.1 MME per patient per year. In 2020, the mean 90-day postoperative amount prescribed was 341.1 MME, which is equivalent to 51 tablets of 5-mg oxycodone (Percocet).

Conclusion

Female sex and younger age were predictors of more MME being prescribed after ARCR. While opioid prescriptions following ARCR have substantially decreased over the past decade, the amount prescribed warrants further attention.

Alternative pain management via endocannabinoids in the time of the opioid epidemic: Peripheral neuromodulation and pharmacological interventions

The use of opioids in pain management is hampered by the emergence of analgesic tolerance, which leads to increased dosing and side effects, both of which have contributed to the opioid epidemic. One promising potential approach to limit opioid analgesic tolerance is activating the endocannabinoid system in the CNS, via activation of CB1 receptors in the descending pain inhibitory pathway. In this review, we first discuss preclinical and clinical evidence revealing the potential of pharmacological activation of CB1 receptors in modulating opioid tolerance, including activation by phytocannabinoids, synthetic CB1 receptor agonists, endocannabinoid degradation enzyme inhibitors, and recently discovered positive allosteric modulators of CB1 receptors. On the other hand, as non-pharmacological pain relief is advocated by the US-NIH to combat the opioid epidemic, we also discuss contributions of peripheral neuromodulation, involving the electrostimulation of peripheral nerves, in addressing chronic pain and opioid tolerance. The involvement of supraspinal endocannabinoid systems in peripheral neuromodulation-induced analgesia is also discussed. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

Association Between State Limits on Opioid Prescribing and the Incidence of Persistent Postoperative Opioid Use Among Surgical Patients

OBJECTIVE

To examine whether laws limiting opioid prescribing have been associated with reductions in the incidence of persistent postoperative opioid use.

SUMMARY OF BACKGROUND DATA

In an effort to address the opioid epidemic, 26 states (as of 2018) have passed laws limiting opioid prescribing for acute pain. However, it is unknown whether these laws have achieved their reduced the risk of persistent postoperative opioid use.

METHODS

We identified 957,639 privately insured patients undergoing one of 10 procedures between January 1, 2004 and September 30, 2018. We then estimated the association between persistent postoperative opioid use, defined as having filled ≥10 prescriptions or ≥120 days supply of opioids during postoperative days 91-365, and whether opioid prescribing limits were in effect on the day of surgery. States were classified as having: no limits, a limit of ≤7 days supply, or a limit of >7 days supply. The regression models adjusted for observable confounders such as patient comorbidities and also utilized a difference-in-differences approach, which relied on variation in state laws over time, to further minimize confounding.

RESULTS

The adjusted incidence of persistent postoperative opioid use was 3.5% (95%CI 3.3%-3.7%) for patients facing a limit of ≤7 days supply, compared with 3.3% (95%CI 3.3%-3.3%) for patients facing no prescribing limits ( P = 0.13 for difference compared to no prescribing limits) and 3.4%, (95%CI 3.2%-3.6%) for patients facing a limit of >7 days supply ( P = 0.43 for difference compared to no prescribing limits).

CONCLUSIONS

Laws limiting opioid prescriptions were not associated with subsequent reductions in persistent postoperative opioid use.

The Opioid-Sparing Effect of Acupuncture After Abdominal Surgery: A Systematic Review and Meta-Analysis Protocol

Purpose

Routine overprescribing of postoperative opioid analgesics may induce side effects and correlate with chronic opioid use following surgery. This review aims to evaluate the effectiveness and safety of acupuncture for opioid-sparing effects in patients who underwent abdominal surgery.

Methods

Eleven databases in different languages, including English (Ovid MEDLINE, CENTRAL, EMBASE, CINAHL), Chinese, Korean, and Japanese, will be searched. Randomized controlled trials using acupuncture for postoperative pain control in adult patients undergoing abdominal surgery will be screened. All randomized controlled trials comparing acupuncture with no treatment, sham acupuncture, and conventional treatments will be included. The Cochrane risk of bias tool will be used to assess the risk of bias. The primary outcome will consist of a cumulative opioid consumption. Additionally, the number of cumulative opioid analgesic demands/requests, the time to initial opioid analgesic usage, postoperative pain, opioid-related side effects, and adverse events of acupuncture will be assessed. The mean differences or risk ratios with a 95% confidence interval will be calculated to estimate the pooled effect of acupuncture when it is possible to conduct a meta-analysis.

Results

This study could confirm the effect of opioid-sparing on acupuncture after abdominal surgery.

Conclusion

This study would evaluate the evidence on the effectiveness of acupuncture after abdominal surgery with a focus on opioid intake. It provides evidence to support decision-making on applying acupuncture for postoperative management.

Registration Number

CRD42022311155.

Opioid prescription trends among American Head and Neck Society fellowship graduates

BACKGROUND

Opioids are commonly used to manage the pain of head and neck (HN) cancer patients.

METHODS

Retrospective cohort of graduates from American Head and Neck Society accredited fellowships from 1997 to 2018. The Center for Medicare and Medicaid Services Part D Provider Utilization and Payment database 2014-2019 was cross-referenced with provider names to identify opioid prescription trends.

RESULTS

From 2014 to 2019, there was no significant difference in the average number of opioid beneficiaries per provider (18.02 vs. 18.10, p = 0.586) or opioid claims per provider (28.06 vs. 26.73, p = 0.708). The average total opioid day supply per beneficiary declined from 11.09 to 7.05 days from 2014 to 2019 (p < 0.001). In 2019, providers in the Northeast had the lowest prescribed opioid day supply (3.67 days) compared to those from the South who had the highest (10.32 days).

CONCLUSIONS

Opioid prescription length has significantly declined among HN surgeons, with variations across geographic regions.

Opioid Use and Associated Patient Satisfaction With Pain Control After Endoscopic Surgery and Robotic-Assisted Radical Prostatectomy

OBJECTIVE

To evaluate patient reported measures in patients undergoing endourologic procedures and robotic assisted radical prostatectomy (RARP) to demonstrate the efficacy of non-opioid postoperative pain management strategies.

MATERIALS AND METHODS

A prospective cohort study performed at an academic medical center included a patient telephone questionnaire and chart review. Opioid prescriptions, opioid use, and patient reported outcomes were recorded. Bivariate analyses were used to compare patients who did and did not use opioids in the RARP cohort while overall trends were reported for the endourologic procedures.

RESULTS

Of the 68 patients undergoing endoscopic intervention, 14 (21%) were prescribed an opioid and 6 (9%) reported any opioid use. 58 (85%) reported their pain was very well or well controlled while 9 reported their pain was poorly controlled. 59 (87%) were satisfied or very satisfied with their pain control. Fifty-three (93%) of the 57 patients undergoing RARP received an opioid prescription and only 23 reported any opioid use. All but 1 patient reported that their pain was well or very well controlled and almost all (54) of the patients were satisfied with their level of pain control. 36 (63%) reported their pain was less than expected while only 7 (12%) reported it was more than expected.

CONCLUSION

Most patients undergoing endourologic procedures do not use postoperative opioids and report favorable outcomes regarding their pain control. Similarly, after RARP, most patients do not use opioids even when they are prescribed and are satisfied with their pain control.

S110-Opioid-free analgesia after outpatient general surgery: A qualitative study focused on the perspectives of patients and clinicians involved in a pilot trial

BACKGROUND

Opioid-free analgesia (OFA) may mitigate opioid-related harms after outpatient general surgery; however, the comparative effectiveness of this approach should be assessed in robust randomized controlled trials (RCTs). Undertaking an RCT on OFA raises important practical concerns, including surgeon and patient hesitation regarding pain management without opioids. We conducted a qualitative study to explore patients' and clinicians' perspectives and experiences with a pilot trial focused on OFA after outpatient general surgery.

METHODS

Patients undergoing outpatient abdominal and breast procedures were randomized to receive post-discharge opioid analgesia (OA) or OFA. Semi-structured interviews with patients and clinicians involved in the trial were conducted to elicit personal perspectives and experiences. Purposive sampling for maximum variation was used to recruit participants with diverse characteristics. Transcribed interviews were assessed using inductive thematic analysis.

RESULTS

Ten patients (5 abdominal, 5 breast) and 10 clinicians (6 surgeons, 2 anesthesiologists, 2 nurses) were interviewed. Five major themes emerged: readiness for trial engagement, pre-trial thoughts about the interventions, postoperative pain experiences, intervention acceptability, and trial refinement. Most patients were open to OFA. Clinicians expressed willingness to prescribe OFA, particularly after less invasive procedures and when using peripheral nerve blocks (PNBs). Concerns were raised regarding the adequacy of pain control and side effects of non-opioid drugs (e.g., NSAID-induced bleeding, kidney injury). Overall, participants were enthusiastic about the trial and recognized its relevance; clinicians praised the study design and organization; and patients valued the use of electronic questionnaires. Suggestions for improvements included preventing potential bias arising from the use of PNBs (i.e., via standardization or stratification) and reducing patient burden (i.e., decreasing postoperative questionnaires).

CONCLUSION

Patients and clinicians who participated in a pilot RCT generally accept the clinical equipoise between OA versus OFA after outpatient general surgery and recognize the need for methodologically robust trials to inform evidence-based analgesia prescribing.

Does a High Postoperative Opioid Dose Predict Chronic Use After ACDF?

OBJECTIVE

The purpose of this study is to determine if increased postoperative prescription opioid dosing is an isolated predictor of chronic opioid use after anterior cervical diskectomy and fusion (ACDF).

METHODS

A retrospective cohort analysis of patients undergoing ACDF for degenerative diseases from 2016-2019 at a single institution was performed. Preoperative and postoperative opioid and benzodiazepine prescriptions, including morphine milligram equivalents (MMEs) and duration of use, were obtained from the Pennsylvania Prescription Drug Monitoring Program. Univariate analysis compared patient demographics and surgical factors across groups on the basis of postoperative opioid dose (high: MME ≥90, low: MME <90) and chronicity of use (chronic: ≥120 days or >10 prescriptions). Logistic regressions identified predictors of high opioid dose and chronic use.

RESULTS

A total of 385 patients were included. Preoperative opioid tolerance and tobacco use were associated with high postoperative opioid dose and chronic usage. Younger age correlated with high-dose prescriptions. Increased body mass index and preoperative benzodiazepine use were associated with chronic opioid use. Chronic postoperative opioid use correlated with high-dose prescriptions, change in opioid prescribed, private pay scripts, and more than 1 prescriber and pharmacy. Logistic regression identified high postoperative opioid dose, opioid tolerance, increased body mass index, and no prior cervical surgery as predictors of chronic opioid use. Regression analysis determined younger age, increased medical comorbidities, and opioid tolerance to be predictors for high MME prescriptions.

CONCLUSIONS

High postoperative opioid dose independently predicted chronic opioid use after ACDF regardless of preoperative opioid tolerance.

Assessment of pain and quality of life in patients undergoing cardiac surgery: a cohort study

OBJECTIVE

This study aimed to evaluate postoperative pain and quality of life in patients undergoing median sternotomy.

METHODS

A cohort study was carried out on a sample of 30 patients who underwent elective cardiac surgery by longitudinal median sternotomy. Patients were interviewed at Intensive Care Unit discharge and hospital discharge, when the Visual Numeric Scale and the Brief Pain Inventory were applied, and 2 weeks after hospital discharge, when the World Health Organization Quality of Life-Bref questionnaire was administered. The normality of the results was analyzed by the Shapiro-Wilk test, and Wilcoxon Rank Sum and McNemar tests were utilized for the analysis of numerical and categorical variables. For correlation between numerical variables, Spearman's linear correlation test was applied. To compare numerical variables, Mann-Whitney U and Kruskal-Wallis tests were applied. Differences between groups were considered significant when the p-value was <0.05.

RESULTS

Between Intensive Care Unit and hospital discharge, there was a reduction in median pain intensity assessed by the Visual Numeric Scale from 5.0 to 2.0 (p<0.001), as well as in eight Brief Pain Inventory parameters: worst pain intensity in the last 24 h (p=0.001), analgesic relief (p=0.035), and pain felt right now (p=0.009); and in interference in daily activities (p<0.001), mood (p=0.017), ability to walk (p<0.001), relationship with other people (p=0.005), and sleep (p=0.006). Higher pain intensity at Intensive Care Unit discharge was associated with worse performance in the psychological domain of quality of life at out-of-hospital follow-up.

CONCLUSION

Proper management of post-sternotomy pain in the Intensive Care Unit may imply better quality of life at out-of-hospital follow-up.

CircRalgapa1 facilitates morphine tolerance via miR-873a-5p/A20 axis in mice

Morphine tolerance (MT) caused by long-term use of morphine is a major medical problem. The underlying molecular mechanisms of morphine tolerance remain unclear. Here, we establish the morphine tolerance model in mice and verify whether a novel circRNA, circRalgapa1 is involved in morphine tolerance and its specific molecular mechanism. We show that the expression of circRalgapa1 in the spinal cord is significantly down-expressed in the spinal cord of morphine-tolerant mice. CircRalgapa1 is mainly located in the neuronal cytoplasm and co-localizes with miR-873a-5p. Mechanically, circRalgapa1 acts as competing endogenous RNAs (ceRNAs) to regulate the inhibitory of miR-873a-5p on A20 (also known as tumor necrosis factor α-induced protein 3, TNFAIP3). Functionally, overexpression of circRalgapa1 by intrathecal injection of adeno-associated virus (AAV- circRalgapa1) attenuated the formation of morphine tolerance and partially reversed the development of morphine tolerance. Moreover, overexpression of miR-873a-5p blocked the effect of AAV-circRalgapa1 on alleviating morphine tolerance in mice. In conclusion, chronic morphine administration-mediated down-regulation of circRalgapa1 in the spinal cord contributes to morphine tolerance via miR-873a-5p/A20 axis in mice. Overexpression of circRalgapa1 may be a promising RNA-based therapy for morphine tolerance.

Toll-like receptor 4 signaling pathway in sensory neurons mediates remifentanil-induced postoperative hyperalgesia via transient receptor potential ankyrin 1

Background: Remifentanil-induced postoperative hyperalgesia (RIH) refers to a state of hyperalgesia or aggravated pre-existing pain after remifentanil exposure. There has been considerable interest in understanding and preventing RIH. However, the mechanisms responsible for RIH are still not completely understood. Toll-like receptor 4 (TLR4), a classic innate immune receptor, has been detected in sensory neurons and participates in various nociceptive conditions, whereas its role in RIH remains unclear. Transient receptor potential ankyrin 1 (TRPA1) always serves as a nociceptive channel, whereas its role in RIH has not yet been investigated. This study aimed to determine whether the TLR4 signaling pathway in sensory neurons engaged in the development of RIH and the possible involvement of TRPA1 during this process. Methods: A rat model of remifentanil-induced postoperative hyperalgesia (RIH) was established, which presented decreased paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). The mRNA and protein expression levels of TLR4, phosphorylated NF-κB, and TRPA1 in the dorsal root ganglion (DRG) from RIH model were analyzed by real-time PCR, western blot, and immunofluorescence. The TLR4 antagonist TAK-242 and the TRPA1 antagonist HC-030031 were applied to determine the role of sensory neuron TLR4 signaling and TRPA1 in RIH. Results: Compared with control, PWMT and PWTL were significantly decreased in RIH model. Moreover, the mRNA and protein expression of TLR4 and TRPA1 in DRG were upregulated after remifentanil exposure together with increased NF-κB phosphorylation. TLR4 antagonist TAK-242 mitigated mechanical pain in RIH together with downregulated expression of TLR4, phosphorylated NF-κB, and TRPA1 in DRG neurons. In addition, TRPA1 antagonist HC-030031 also alleviated mechanical pain and decreased TRPA1 expression in RIH without affecting TLR4 signaling in DRG. Conclusions: Taken together, these results suggested that activation of TLR4 signaling pathway engaged in the development of RIH by regulating TRPA1 in DRG neurons. Blocking TLR4 and TRPA1 might serve as a promising therapeutic strategy for RIH.

A Neural Network Model Using Pain Score Patterns to Predict the Need for Outpatient Opioid Refills Following Ambulatory Surgery: Algorithm Development and Validation

BACKGROUND

Expansion of clinical guidance tools is crucial to identify patients at risk of requiring an opioid refill after outpatient surgery.

OBJECTIVE

The objective of this study was to develop machine learning algorithms incorporating pain and opioid features to predict the need for outpatient opioid refills following ambulatory surgery.

METHODS

Neural networks, regression, random forest, and a support vector machine were used to evaluate the data set. For each model, oversampling and undersampling techniques were implemented to balance the data set. Hyperparameter tuning based on k-fold cross-validation was performed, and feature importance was ranked based on a Shapley Additive Explanations (SHAP) explainer model. To assess performance, we calculated the average area under the receiver operating characteristics curve (AUC), F1-score, sensitivity, and specificity for each model.

RESULTS

There were 1333 patients, of whom 144 (10.8%) refilled their opioid prescription within 2 weeks after outpatient surgery. The average AUC calculated from k-fold cross-validation was 0.71 for the neural network model. When the model was validated on the test set, the AUC was 0.75. The features with the highest impact on model output were performance of a regional nerve block, postanesthesia care unit maximum pain score, postanesthesia care unit median pain score, active smoking history, and total perioperative opioid consumption.

CONCLUSIONS

Applying machine learning algorithms allows providers to better predict outcomes that require specialized health care resources such as transitional pain clinics. This model can aid as a clinical decision support for early identification of at-risk patients who may benefit from transitional pain clinic care perioperatively in ambulatory surgery.

Postsurgical Opioid Use Among Veterans Discharged to Skilled Care Facilities Compared to Veterans Discharged to Home After Orthopedic Surgery

OBJECTIVES

To compare opioid use patterns among Veterans who were discharged to a skilled care facility vs home after orthopedic surgery at a VA hospital.

DESIGN

We conducted a retrospective cohort study of Veterans who had orthopedic surgery at the Salt Lake City VA Medical Center (VAMC) between January 2018 and December 2021 and were followed by a transitional pain service. The principal outcome of interest was the time to stop opioid use after discharge from the hospital.

SETTING AND PARTICIPANTS

Veterans not already on chronic opioid therapy who had orthopedic surgery at the Salt Lake City VAMC and were followed by a transitional pain service.

METHODS

448 patients were included in the study, of which 371 (83%) were discharged to home and 77 (17%) were discharged to a skilled care facility. Median days to opioid cessation were estimated using the Kaplan-Meier method with 95% CIs and compared with discharge disposition using a log-rank test. Time to opioid cessation following hospital discharge was compared to baseline characteristics using univariable and multivariable Cox proportional hazards models.

RESULTS

Patients who were discharged to a skilled care facility used opioids for twice as long as those who were discharged home [median days (interquartile range)]: 22 (19, 26) vs 11 (10, 12), P < .001, respectively. When controlling for baseline characteristics in the multivariable analysis, discharge to a skilled care facility was significantly associated with continued opioid use at all time points [hazard ratio 0.63 (95% CI 0.44, 0.89), P = .009].

CONCLUSIONS AND IMPLICATIONS

Veterans discharged to a skilled care facility after orthopedic surgery used opioids for twice as long as those who were discharged to home. As postsurgical pain management guidelines change to focus on nonopioid pain modalities and opioid reduction, skilled care providers should adapt those strategies for their facilities.

Impact of Perioperative Ketamine on Postoperative Bariatric Surgery Opioid Use and Length of Stay

SETTINGS

Postoperative pain management is an ever-growing challenge with the rise of the opioid crisis. Ketamine is an NMDA channel blocker, considered an alternative to perioperative opioid use; small concentrations are safe. Objective: The primary objective of this study was to evaluate the impact of perioperative ketamine administration on postoperative opioid use and the length of hospital stay in bariatric patients.

METHODS

Four hundred (366) charts were retrospectively reviewed; of those, 187 received ketamine and were placed in the Ketamine group, 179 received standard-of-care pain management and were part of the No-Ketamine group. Data was collected using medical databases from July 2020 to January 2021.

RESULTS

A greater length of stay was recorded in the No-Ketamine group (45.67±20.6 hours) when compared with the Ketamine group (40.6±14.3 hours); P <0.05. The Ketamine group had a mean MME of 17.5±16.5 whereas the No-Ketamine had a mean MME of 22.3±17.7, P <0.05.

CONCLUSIONS

Ketamine may be a feasible alternative to reduce opioid use and hospital length of stay. We believe that ketamine can be an important contribution to ERABS pathways, being responsible for improved outcomes after bariatric/metabolic surgical procedures.

Minimal important difference in opioid consumption based on adverse event reduction-A study protocol

BACKGROUND

The patient-relevant minimal important difference for opioid consumption remains undetermined, despite its frequent use as primary outcome in trials on postoperative pain management. A minimal important difference is necessary to evaluate whether significant trial results are clinically relevant. Further, it can be used as effect size to ensure that trials are powered to find clinically relevant effects. By exploring the dose-response relationship between postoperative opioid consumption and opioid-related adverse effects, we aim to approximate the minimal important difference in opioid consumption anchored to opioid-related adverse effects.

METHODS

This is a post-hoc analysis of aggregated data from two clinical trials (PANSAID NCT02571361 and DEX2TKA NCT03506789) and one observational cohort study (Pain Map NCT02340052) on pain management after total hip and knee arthroplasty. The primary outcome is the Hodges-Lehmann median difference in opioid consumption between patients with no opioid-related adverse effects and patients experiencing the mildest degree of one or more opioid-related adverse effects (i.e., mild nausea, sedation and/or dizziness or vomiting). Secondary outcomes include the Hodges-Lehmann median difference in opioid consumption that corresponds to one point on a cumulated opioid-related adverse event 0-10 scale. Further, we will explore the proportion of patients that experience opioid-related adverse effects for consecutive opioid dose intervals of 2 mg iv morphine equivalents. Quantile regression will be used to assess any significant interactions with patient baseline characteristics.

CONCLUSIONS

This study will hopefully bring us one step closer to determining relevant opioid reductions and thereby improve our understanding of intervention effects and planning of future trials.

Integrative Surgery: Embedding Complementary and Nonpharmacologic Therapies into Surgical Pain Management Strategies

There has been a growing interest in the use of complementary and alternative medicine in modern pain management strategies on behalf of both patients and clinicians. Nonpharmacologic modalities such as cryotherapy, acupuncture, music, and mind-body therapies have been shown to aid in symptom control and improve quality of life in patients suffering from acute and chronic pain, and there is a growing body of literature demonstrating their feasibility, acceptability, and efficacy in the perioperative period. Here, we provide a brief review of the current evidence supporting the use of complementary therapies within existing perioperative pain management strategies and highlight evidence-based protocols to facilitate implementation into modern surgical practice.

The Effect of Cryotherapy Application on Postoperative Pain: A Systematic Review and Meta-analysis

OBJECTIVE

To systematically review and meta-analyze whether the application of cryotherapy on closed incisions reduces postoperative pain and opioid consumption.

BACKGROUND

Reduction of acute pain and opioid use is important in the postoperative phase of patient care. ''Cryotherapy'' refers to the use of low temperatures for therapeutic purposes.

METHODS

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Online registries of clinical trial were search until October 2019. RCT that examined postoperative application of cryotherapy over surgical incisions in adults compared to no cryotherapy were eligible. Selection, extraction, and risk of bias appraisal were completed in duplicate. Data were synthesized using random effects meta-analyses. The outcomes of interest were postoperative pain, opioid use, hospital length of stay (LOS) and surgical site infection (SSI).

RESULTS

Fifty-one RCTs (N = 3425 patients) were included. With moderate certainty evidence, patients treated with cryotherapy experienced a reduction in pain on postoperative day 1 (standardized mean differences -0.50, 95% CI -0.71 to -0.29, l 2= 74%) and day 2 (standardized mean differences -0.63, 95% CI -0.91 to -0.35, I 2 = 83%) relative to without cryotherapy application. With moderate certainty of evidence, cryotherapy reduces opioid consumption in morphine milliequivalents and morphine milliequivalents/kg, (mean differences -7.43, 95% CI -12.42, -2.44, I 2 = 96%) and (mean differences -0.89, 95% CI -1.45, -0.33, I 2 = 99%), respectively. With low certainty evidence, cryotherapy does not affect hospital LOS or rate of SSI.

CONCLUSION

Cryotherapy is a pragmatic, noncostly intervention that reduces postoperative pain and opioid consumption with no effect on SSI rate or hospital LOS.

Prediction of acute postoperative pain based on intraoperative nociception level (NOL) index values: the impact of machine learning-based analysis

The relationship between intraoperative nociception and acute postoperative pain is still not well established. The nociception level (NOL) Index (Medasense, Ramat Gan, Israel) uses a multiparametric approach to provide a 0-100 nociception score. The objective of the ancillary analysis of the NOLGYN study was to evaluate the ability of a machine-learning aglorithm to predict moderate to severe acute postoperative pain based on intraoperative NOL values. Our study uses the data from the NOLGYN study, a randomized controlled trial that evaluated the impact of NOL-guided intraoperative administration of fentanyl on overall fentanyl consumption compared to standard of care. Seventy patients (ASA class I-III, aged 18-75 years) scheduled for gynecological laparoscopic surgery were enrolled. Variables included baseline demographics, NOL reaction to incision or intubation, median NOL during surgery, NOL time-weighted average (TWA) above or under manufacturers' recommended thresholds (10-25), and percentage of surgical time spent with NOL > 25 or < 10. We evaluated different machine learning algorithms to predict postoperative pain. Performance was assessed using cross-validated area under the ROC curve (CV-AUC). Of the 66 patients analyzed, 42 (63.6%) experienced moderate to severe pain. NOL post-intubation (42.8 (31.8-50.6) vs. 34.8 (25.6-41.3), p = 0.05), median NOL during surgery (13 (11-15) vs. 11 (8-13), p = 0.027), percentage of surgical time spent with NOL > 25 (23% (18-18) vs. 20% (15-24), p = 0.036), NOL TWA < 10 (2.54 (2.1-3.0) vs. 2.86 (2.48-3.62), p = 0.044) and percentage of surgical time spent with NOL < 10 (41% (36-47) vs. 47% (40-55), p = 0.022) were associated with moderate to severe PACU pain. Corresponding ROC AUC for the prediction of moderate to severe PACU pain were 0.65 [0.51-0.79], 0.66 [0.52-0.81], 0.66 [0.52-0.79], 0.65 [0.51-0.79] and 0.67 [0.53-0.81]. Penalized logistic regression achieved the best performance with a 0.753 (0.718-0.788) CV-AUC. Our results, even if limited by the small number of patients, suggest that acute postoperative pain is better predicted by a multivariate machine-learning algorithm rather than individual intraoperative nociception variables. Further larger multicentric trials are highly recommended to better understand the relationship between intraoperative nociception and acute postoperative pain.Trial registration Registered on ClinicalTrials.gov in October 2018 (NCT03776838).