Acute pain trajectories and the persistence of post-surgical pain: a longitudinal study after total hip arthroplasty

Acute pain trajectories in elderly patients with fragility hip fractures

BACKGROUND

Pain management for hospitalized elderly patients with fragility hip fractures (FHF) remains challenging. This study aims to distinguish acute pain trajectories in FHF patients that can inform personalized analgesia management.

METHODS

We conducted a prospective observational study of patients aged 65 and older with FHF at a Level I trauma center. The primary outcome was daily average pain assessed for five days post-injury using the Brief Pain Inventory (BPI). We used group-based trajectory modeling (GBTM) to distinguish acute pain trajectories. Then, factors and secondary outcomes (opioid use and hospital length of stay [LOS]) associated with more severe pain trajectories were identified.

RESULTS

We enrolled 100 consecutive patients with FHF between June 2022 and June 2023. We identified three distinct acute pain trajectories: minimal pain, subsiding pain, and persistent pain. Factors associated with more severe pain trajectories included higher initial pain on admission (OR 1.17, 95 % CI 1.02-1.36, P = 0.047), higher BMI (OR 1.15, 95 % CI 1.02-1.29, P = 0.021), and intertrochanteric fracture type (OR = 6.46, 95 % CI 1.49-27.98, P = 0.013). The persistent pain trajectory was significantly associated with 40 % more opioid use (P = 0.01) and a longer LOS (LOS ratio = 1.45, 95 % CI 1.21-1.74, P < 0.001).

CONCLUSION

Acute pain in FHF patients can be classified into distinct trajectories, providing a basis for personalized pain management. More severe pain trajectories are associated with higher opioid use and longer length of hospital stay.

Ten years of transitional pain service research and practice: where are we and where do we go from here?

Chronic postsurgical pain (CPSP) is a prevalent yet unintended consequence of surgery with substantial burdens to the individual and their family, the healthcare system, and society at large. The present article briefly reviews the evidence for transitional pain services (TPSs) that have arisen in an effort to prevent and mange CPSP and persistent opioid use, and provides an update on recent novel risk factors for CPSP. Available evidence from one randomized controlled trial (RCT) and three non-randomized cohort studies suggests that TPS treatment is associated with better opioid use outcomes, including fewer opioid tablets prescribed at discharge, better opioid weaning results, a lower incidence of new-onset chronic opioid use, and lower consumption of opioids even at later time points up to 1 year after surgery. Another RCT indicates TPS treatment can be enhanced by provision of perioperative clinical hypnosis. While these preliminary studies are generally positive, large-scale, RCTs are needed to provide a more definitive picture of whether TPSs are effective in reducing opioid consumption and improving pain and mental health outcomes in the short and long term. With the expansion of TPSs across North America and globally, perioperative care focused on reducing the transition to pain chronicity has the potential to help millions of patients. With additional evidence from well-controlled RCTs, TPSs are well poised to continue to evolve and strengthen the role of multidisciplinary care teams in the immediate postdischarge period and beyond.

Postoperative acute pain trajectory and chronic postsurgical pain after abdominal surgery: a prospective cohort study and mediation analysis

BACKGROUND

This study aimed to investigate the trajectories of acute postoperative pain intensity during the initial 5 days after abdominal surgery, and to analyze their association with the risk of developing chronic postsurgical pain (CPSP).

METHODS

We enrolled patients with elective abdominal surgery with pain measurements taken across postoperative days 1 through 5. Since postoperative pain is often unavoidable and its initial intensity is closely related to the invasiveness of the surgery, focusing on the overall pain trajectory may be more meaningful than evaluating pain at a single time point. Therefore, the primary outcome of this study was to identify distinct pain trajectories. Secondary outcome was the incidence of CPSP between differences pain trajectories. Lastly, mediation analyses were performed to explore the mediating role of the quality of recovery and subacute pain on the studied associations.

RESULTS

The final analysis encompassed 1170 patients (36.75% female) with a median age of 55 years. Two distinct clusters were identified: with movement (high: 533 [45.56%]; low: 637 [54.44%]) and at rest (high: 363 [31.03%]; low: 807 [68.97%]). Patients in the high pain trajectory group (during movement [odds ratio [OR] 2.04, 95% CI 1.56-2.68] or at rest [OR 1.90, 95% CI 1.44-2.53]) exhibited nearly doubled risk of CPSP. Moreover, these patients exhibited a significantly poorer recovery quality. Mediation analyses revealed that the poor recovery quality at postoperative 5 days (17.62%-18.57%) and higher subacute pain at postoperative 1 month (29.46%-32.75%) were significant mediators in the association between adverse postoperative acute pain trajectory patterns and CPSP.

CONCLUSION

This study highlights the clinical significance of postoperative pain trajectory profiles in predicting the risk of CPSP, emphasizing postoperative acute pain trajectory as a critical indicator and subacute pain as a significant mediator. The findings underscore the potential for tailored pain management strategies targeting acute pain trajectories to reduce such risk.

A Prospective Cohort Study of Acute Pain and In-Hospital Opioid Consumption After Cardiac Surgery: Associations With Psychological and Medical Factors and Chronic Postsurgical Pain

BACKGROUND

Understanding the association of acute pain intensity and opioid consumption after cardiac surgery with chronic postsurgical pain (CPSP) can facilitate implementation of personalized prevention measures to improve outcomes. The objectives were to (1) examine acute pain intensity and daily mg morphine equivalent dose (MME/day) trajectories after cardiac surgery, (2) identify factors associated with pain intensity and opioid consumption trajectories, and (3) assess whether pain intensity and opioid consumption trajectories are risk factors for CPSP.

METHODS

Prospective observational cohort study design conducted between August 2012 and June 2020 with 1-year follow-up. A total of 1115 adults undergoing cardiac surgery were recruited from the preoperative clinic. Of the 959 participants included in the analyses, 573 completed the 1-year follow-up. Main outcomes were pain intensity scores and MME/day consumption over the first 6 postoperative days (PODs) analyzed using latent growth mixture modeling (GMM). Secondary outcome was 12-month CPSP status.

RESULTS

Participants were mostly male (76%), with a mean age of 61 ± 13 years. Three distinct linear acute postoperative pain intensity trajectories were identified: "initially moderate pain intensity remaining moderate" (n = 62), "initially mild pain intensity remaining mild" (n = 221), and "initially moderate pain intensity decreasing to mild" (n = 251). Age, sex, emotional distress in response to bodily sensations, and sensitivity to pain traumatization were significantly associated with pain intensity trajectories. Three distinct opioid consumption trajectories were identified on the log MME/day: "initially high level of MME/day gradually decreasing" (n = 89), "initially low level of MME/day remaining low" (n = 108), and "initially moderate level of MME/day decreasing to low" (n = 329). Age and emotional distress in response to bodily sensations were associated with trajectory membership. Individuals in the "initially mild pain intensity remaining mild" trajectory were less likely than those in the "initially moderate pain intensity remaining moderate" trajectory to report CPSP (odds ratio [95% confidence interval, CI], 0.23 [0.06-0.88]). No significant associations were observed between opioid consumption trajectory membership and CPSP status (odds ratio [95% CI], 0.84 [0.28-2.54] and 0.95 [0.22-4.13]).

CONCLUSIONS

Those with moderate pain intensity right after surgery are more likely to develop CPSP suggesting that those patients should be flagged early on in their postoperative recovery to attempt to alter their trajectory and prevent CPSP. Emotional distress in response to bodily sensations is the only consistent modifiable factor associated with both pain and opioid trajectories.

Trajectories of pain intensity, pain catastrophizing, and pain interference in the perinatal and postpartum period

Introduction

Chronic pain (pain >3 months) is a growing epidemic. Normal pregnancy may give rise to recurrent and sometimes constant pain for women. Women with worse pain symptoms are more likely to report symptoms of anxiety, depression, and/or insomnia during the perinatal period, which may impact labor and delivery outcomes. We examined the relationship between demographic and psychological predictors of pain throughout pregnancy and into the postpartum.

Objectives

To examine trajectories of pain intensity, pain catastrophizing, and pain interference during pregnancy and the early postpartum, and associated sociodemographic predictors of trajectory membership.

Methods

One hundred forty-two pregnant women were assessed at 4 time points for measures of pain intensity, pain catastrophizing, pain interference, and symptoms of insomnia, depression, and generalized anxiety. Women completed the first survey before 20 weeks' gestation and were reassessed every 10 weeks. Surveys were completed on average at 15 weeks', 25 weeks', and 35 weeks' gestation, and at 6-week postpartum. Using latent class mixed models, trajectory analysis was used to determine trajectories of pain intensity, pain catastrophizing, and pain interference.

Results

A 1-class pain intensity model, 2-class pain catastrophizing model, and 3-class pain interference model were identified. Adaptive lasso and imputation demonstrated model robustness. Individual associations with trajectories included baseline symptoms of anxiety, depression, and insomnia, and pain symptomology.

Conclusion

These findings may help to identify women who are at high risk for experiencing pain symptoms during pregnancy and could aid in developing targeted management strategies to prevent mothers from developing chronic pain during their pregnancy and into the postpartum period.

Patient Experiences and Clinical Outcomes in a Multidisciplinary Perioperative Transitional Pain Service

Siloed pain management across the perioperative period increases the risk of chronic opioid use and impedes postoperative recovery. Transitional perioperative pain services (TPSs) are innovative care models that coordinate multidisciplinary perioperative pain management to mitigate risks of chronic postoperative pain and opioid use. The objective of this study was to examine patients' experiences with and quality of recovery after participation in a TPS. Qualitative interviews were conducted with 26 patients from The Johns Hopkins Personalized Pain Program (PPP) an average of 33 months after their first PPP visit. A qualitative content analysis of the interview data showed that participants (1) valued pain expectation setting, individualized care, a trusting patient-physician relationship, and shared decision-making; (2) perceived psychiatric treatment of co-occurring depression, anxiety, and maladaptive behaviors as critical to recovery; and (3) successfully sustained opioid tapers and experienced improved functioning after PPP discharge. Areas for improved patient-centered care included increased patient education, specifically about the program, continuity of care with pain specialists while tapering opioids, and addressing the health determinants that impede access to pain care. The positive patient experiences and sustained clinical benefits for high-risk complex surgical patient support further efforts to implement and adapt similar models of perioperative pain care.

Psychological predictors of acute postoperative pain after total knee and hip arthroplasty: A systematic review

BACKGROUND

Identifying patients at high risk of acute postoperative pain after total knee or hip arthroplasty (TKA/THA) will facilitate individualized pain management and research on the efficacy of treatment options. Numerous studies have reported that psychological patient factors may influence acute postoperative pain, but most reviews have focused on chronic pain and functional outcomes. This systematic review aims to evaluate which psychological metrics are associated with acute postoperative pain after TKA and THA.

METHODS

A systematic search was conducted using the databases PubMed, EMBASE, Web of Science, and Cochrane Library until June 2022. Full-text articles reporting associations of preoperative psychological factors with acute pain within 48 h of TKA or THA surgery were identified. Quality was assessed using the Quality in Prognostic Studies tool.

RESULTS

Eighteen studies containing 16 unique study populations were included. TKA was the most common procedure, and anxiety and depression were the most evaluated psychological metrics. Several different anesthetic techniques and analgesic regimens were used. The studies were generally rated as having a low to moderate risk of bias. Catastrophizing was associated with acute pain in six studies (of nine), mainly after TKA. In contrast, three studies (of 13) and two studies (of 13) found anxiety and depression, respectively, to be associated with acute postoperative pain.

CONCLUSION

Pain catastrophizing seemed to be the most consistent psychological predictor of acute postoperative pain after TKA. The results for other psychological factors and THA were inconsistent. However, the interpretation of results was limited by considerable methodological heterogeneity.

The mechanisms and management of persistent postsurgical pain

An estimated 10%-50% of patients undergoing a surgical intervention will develop persistent postsurgical pain (PPP) lasting more than 3 months despite adequate acute pain management and the availability of minimally invasive procedures. The link between early and late pain outcomes for surgical procedures remains unclear-some patients improve while others develop persistent pain. The elective nature of a surgical procedure offers a unique opportunity for prophylactic or early intervention to prevent the development of PPP and improve our understanding of its associated risk factors, such as pre-operative anxiety and the duration of severe acute postoperative pain. Current perioperative pain management strategies often include opioids, but long-term consumption can lead to tolerance, addiction, opioid-induced hyperalgesia, and death. Pre-clinical models provide the opportunity to dissect mechanisms underpinning the transition from acute to chronic, or persistent, postsurgical pain. This review highlights putative mechanisms of PPP, including sensitisation of peripheral sensory neurons, neuroplasticity in the central nervous system and nociceptive signalling along the neuro-immune axis.

A clinical tool to predict severe pain during wound dressing changes

ABSTRACT

Dressing changes cause severe pain (ie, 8-10 on a 10-point scale) for approximately one-third (36%) of patients with open skin wounds. No tool exists that allows nurses to predict which patients are likely to experience severe pain during dressing changes. The aim of this study was to develop a clinical tool to predict severe pain during dressing changes using clinically accessible wound and pain predictors and to evaluate the diagnostic validity of this model. Using a cross-sectional design, a one-time study dressing change was conducted by the same wound care nurse on 445 subjects while concurrently measuring patient and wound predictors and pain intensity during the dressing change. Three predictors came out of the study as most useful for a clinical prediction tool: type of dressing, resting wound pain, and expected pain. Algorithms based on these predictors are presented, which can be applied in other settings to predict patients likely to experience severe pain during a dressing change. This is the first study to systematically examine a comprehensive set of wound and patient predictors for their individual and collective associations with pain during dressing changes using precisely defined and rigorously measured study variables. The ability to predict which patients are likely to have severe pain during dressing changes is critically needed so that they can be targeted for preventive pain control strategies.

Worst pain intensity and opioid intake during the early postoperative period were not associated with moderate-severe pain 12 months after total knee arthroplasty - a longitudinal study

OBJECTIVES

There are several known predictors of pain after total knee arthroplasty (TKA). However, it is unclear whether acute postoperative pain intensity and postoperative opioid intake are associated with pain 12 months after TKA. Thus, the aim of this study was to assess whether worst pain intensity and opioid intake during the early postoperative period are associated with moderate-severe pain 12 months after TKA.

METHODS

A total of 202 patients undergoing primary TKA between October 2012 and September 2014 were prospectively enrolled. Age, sex, contralateral knee pain, BMI, physical status and opioid intake were collected preoperatively. Ketamine and daily opioid intake were collected on postoperative days (POD) 0-3. Using the Brief Pain Inventory, patients' "worst pain intensity" was measured preoperatively, on POD 0-4, and 12 months after TKA. Two logistic regression models evaluated the independent association of early postoperative pain intensity (model 1) and postoperative opioid intake (model 2) with moderate-severe pain 12 months after TKA, adjusting for possible confounders.

RESULTS

In total, 187 patients with data at the 12 month postoperative follow-up were included in this analysis. Pain intensity on POD2 and POD3, as well as preoperative pain and BMI, were significantly associated with pain at 12 months in univariate models. However, in multivariable models adjusted for preoperative pain and BMI, neither pain intensity on POD 0-4 (model 1) nor opioid intake on POD 0-3 (model 2) were associated with pain at 12 months. Preoperative pain was still significant in both models, but BMI remained significant only in model 2.

CONCLUSIONS

Worst pain intensity and opioid intake during the early postoperative period were not associated with moderate-severe pain 12 months after TKA when controlling for potential confounders. More research is needed to confirm these findings.

Predictors and predictive effects of acute pain trajectories after gastrointestinal surgery

Few studies have investigated factors associated with acute postsurgical pain (APSP) trajectories, and whether the APSP trajectory can predict chronic postsurgical pain (CPSP) remains unclear. We aimed to identify the predictors of APSP trajectories in patients undergoing gastrointestinal surgery. Moreover, we hypothesised that APSP trajectories were independently associated with CPSP. We conducted a prospective cohort study of 282 patients undergoing gastrointestinal surgery to describe APSP trajectories. Psychological questionnaires were administered 1 day before surgery. Meanwhile, demographic characteristics and perioperative data were collected. Average pain intensity during the first 7 days after surgery was assessed by a numeric rating scale (NRS). Persistent pain intensity was evaluated at 3 and 6 months postoperatively by phone call interview. CPSP was defined as pain at the incision site or surrounding areas of surgery with a pain NRS score ≥ 1 at rest. The intercept and slope were calculated by linear regression using the least squares method. The predictors for the APSP trajectory and CPSP were determined using multiple linear regression and multivariate logistic regression, respectively. Body mass index, morphine milligram equivalent (MME) consumption, preoperative chronic pain and anxiety were predictors of the APSP trajectory intercept. Moreover, MME consumption and preoperative anxiety could independently predict the APSP trajectory slope. The incidence of CPSP at 3 and 6 months was 30.58% and 16.42% respectively. APSP trajectory and age were predictors of CPSP 3 months postoperatively, while female sex and preoperative anxiety were predictive factors of CPSP 6 months postoperatively. Preoperative anxiety and postoperative analgesic consumption can predict APSP trajectory. In addition, pain trajectory was associated with CPSP. Clinicians need to stay alert for these predictors and pay close attention to pain resolution.

Multidimensional Perioperative Recovery Trajectories in a Mixed Surgical Cohort: A Longitudinal Cluster Analysis Utilizing National Institutes of Health Patient-Reported Outcome Measurement Information System Measures

BACKGROUND

Pain trajectories have been described in numerous surgical settings where preoperative characteristics have been used to predict trajectory membership. Suboptimal pain intensity trajectories have been linked to poor longitudinal outcomes. However, numerous biopsychosocial modulators of postoperative pain may also have distinct longitudinal trajectories that may inform additional targets to improve postoperative recovery.

METHODS

Patients undergoing total joint arthroplasty, thoracic surgery, spine surgery, major abdominal surgery, or mastectomy completed Patient Reported Outcome Measurement Information System (PROMIS) measures and additional scales preoperatively and at 1 week, 2 weeks, 1 month, 3 months, and 6 months postoperatively. A k-means clustering for longitudinal data was utilized to explore and describe distinct pain impact (PROMIS Pain Interference and Physical Function) trajectories and associated changes in additional biopsychosocial measures. Follow-up analyses examined participant demographics and clinical characteristics associated with trajectory memberships.

RESULTS

Three postoperative biopsychosocial symptom clusters were identified across all patients (n = 402): low (35%), average (47%), and high (18%) performance cluster trajectories. Participants undergoing total knee arthroplasty (TKA), spinal surgery, reporting presurgical opioid use, and higher pain catastrophizing scale scores were found to be associated with the low performance trajectory. Patients within the low performance trajectory, while demonstrating small improvements by 6 months, remained mild to moderately impaired in both pain impact and physical health outcomes. Alternatively, participants in the average performance trajectory demonstrated improvement in pain impact to population norms compared to baseline and demonstrated continued improvement across physical and psychological outcomes. Patients within the high performance cluster started within population norms across all measures at baseline and returned to baseline or exceeded baseline values by 6 months postoperatively. Self-reported opioid utilization was significantly higher in the low performance cluster across all time points. While a larger proportion of average performance patients reported opioid utilization during the first postoperative month compared to the high performance cluster, no differences were detected at 6 months postoperatively between these 2 clusters.

CONCLUSIONS

These pain impact trajectories build upon previous unidimensional pain intensity trajectories and suggest that additional distinct biopsychosocial measures may have unique trajectories related to cluster assignment. Additionally, these findings highlight the importance of continued pain impact surveillance through the perioperative recovery period to detect patients at risk of experiencing a poor trajectory and subsequently poor longitudinal health outcomes.

Psychological factors and trajectories of post-surgical pain: A longitudinal prospective study

A significant proportion of patients do not experience relief from pain during the early postsurgical period after joint arthroplasty and are at risk for developing chronic pain. The objectives of this study were to identify biopsychosocial factors associated with acute postsurgical pain trajectories and with pain intensity and interference after 1, 3, and 12 months. Two hundred ten patients listed for joint arthroplasty filled a presurgical battery of questionnaires assessing presurgical pain intensity, catastrophizing, emotional distress, state anxiety and depression, self-efficacy, central sensitization, and executive functions. From the day after surgery, they were asked to fill a 7-day diary, including questions about postsurgical pain and postsurgical state catastrophizing. Finally, they provided data about pain intensity and interference after 1, 3, and 12 months. Predictors of acute pain trajectories were investigated using multilevel growth curve analysis. Results showed that central sensitization was a predictor of the intercept of pain trajectories and daily postsurgical catastrophizing was a significant covariate of pain intensity in the acute phase. Analyses of follow-up data showed that central sensitization was a predictor of pain intensity and pain interference at 3 and 12 months, that emotional distress was related with pain intensity and interference at 1 month, and with pain interference at 3 months, and that cognitive flexibility was associated with pain interference at 1 month. Assessment of these factors could enable to identify patients at risk for worse outcomes and to plan targeted treatments to be implemented during the patient's inward stay.

Automated Pain Assessment in Children using Electrodermal Activity and Video Data Fusion via Machine Learning

Pain assessment in children continues to challenge clinicians and researchers, as subjective experiences of pain require inference through observable behaviors, both involuntary and deliberate. The presented approach supplements the subjective self-report-based method by fusing electrodermal activity (EDA) recordings with video facial expressions to develop an objective pain assessment metric. Such an approach is specifically important for assessing pain in children who are not capable of providing accurate self-pain reports, requiring nonverbal pain assessment. We demonstrate the performance of our approach using data recorded from children in post-operative recovery following laparoscopic appendectomy. We examined separately and combined the usefulness of EDA and video facial expression data as predictors of childrens self-reports of pain following surgery through recovery. Findings indicate that EDA and facial expression data independently provide above chance sensitivities and specificities, but their fusion for classifying clinically significant pain vs. clinically nonsignificant pain achieved substantial improvement, yielding 90.91% accuracy, with 100% sensitivity and 81.82% specificity. The multimodal measures capitalize upon different features of the complex pain response. Thus, this paper presents both evidence for the utility of a weighted maximum likelihood algorithm as a novel feature selection method for EDA and video facial expression data and an accurate and objective automated classification algorithm capable of discriminating clinically significant pain from clinically nonsignificant pain in children.

Correlation between pain severity and levels of anxiety and depression in osteoarthritis patients: a systematic review and meta-analysis

OBJECTIVES

Osteoarthritis (OA) is a chronic degenerative musculoskeletal disease that causes articular damage and chronic pain, with a prevalence of up to 50% in individuals >60 years of age. Patients suffering from chronic painful conditions, including OA, also frequently report anxiety or depression. A systematic review and meta-analysis were performed to assess the correlation between pain severity and depressive and anxious symptomatology in OA patients.

METHODS

A systematic search was conducted using four databases (PubMed, Medline, Scopus, and Web of Science) from inception up to 14th January of 2020. We included original articles evaluating pain severity and anxiety and/or depression severity in OA-diagnosed patients. Detailed data were extracted from each study, including patients' characteristics and pain, anxiety, and depression severity. When available, the Pearson correlation coefficient between pain and depression severity and pain and anxiety severity was collected and a meta-analysis of random effects was applied.

RESULTS

This systematic review included 121 studies, with a total of 38085 participants. The mean age was 64.3 years old and subjects were predominantly female (63%). The most used scale to evaluate pain severity was the Western Ontario and the McMaster Universities Osteoarthritis Index, while for anxiety and depression, the Hospital Anxiety and Depression Scale was the most used. The meta-analysis showed a moderate positive correlation between pain severity and both anxious (r = 0.31, p < 0.001) and depressive symptomatology (r = 0.36, p < 0.001).

CONCLUSIONS

Our results demonstrate a significant correlation between pain and depression/anxiety severity in OA patients, highlighting the need for its routine evaluation by clinicians.

AAAPT: Assessment of the Acute Pain Trajectory

OBJECTIVE

Define and contrast acute pain trajectories vs. the aggregate pain measurements, summarize appropriate linear and nonlinear statistical analyses for pain trajectories at the patient level, and present methods to classify individual pain trajectories. Clinical applications of acute pain trajectories are also discussed.

SETTING

In 2016, an expert panel involving the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), American Pain Society (APS), and American Academy of Pain Medicine (AAPM) established an initiative to create a pain taxonomy, named the ACTTION-APS-AAPM Pain Taxonomy (AAAPT), for the multidimensional classification of acute pain. The AAAPT panel commissioned the present report to provide further details on analysis of the individual acute pain trajectory as an important component of comprehensive pain assessment.

METHODS

Linear mixed models and nonlinear models (e.g., regression splines and polynomial models) can be applied to analyze the acute pain trajectory. Alternatively, methods for classifying individual pain trajectories (e.g., using the 50% confidence interval of the random slope approach or using latent class analyses) can be applied in the clinical context to identify different trajectories of resolving pain (e.g., rapid reduction or slow reduction) or persisting pain. Each approach has advantages and disadvantages that may guide selection. Assessment of the acute pain trajectory may guide treatment and tailoring to anticipated symptom recovery. The acute pain trajectory can also serve as a treatment outcome measure, informing further management.

CONCLUSIONS

Application of trajectory approaches to acute pain assessments enables more comprehensive measurement of acute pain, which forms the cornerstone of accurate classification and treatment of pain.

Predictors of one year chronic post-surgical pain trajectories following thoracic surgery

PURPOSE

Chronic post-surgical pain (CPSP) is a highly prevalent complication following thoracic surgery. This is a prospective cohort study that aims to describe the pain trajectories of patients undergoing thoracic surgery beginning preoperatively and up to 1 year after surgery METHODS: Two hundred and seventy nine patients undergoing elective thoracic surgery were enrolled. Participants filled out a preoperative questionnaire containing questions about their sociodemographic information, comorbidities as well as several psychological and pain-related statuses. They were then followed-up during their immediate postoperative period and at the three, six and 12 month time-points to track their postoperative pain, complications and pain-related outcomes. Growth mixture modeling was used to construct pain trajectories.

RESULTS

The first trajectory is characterized by 185 patients (78.1%) with mild pain intensity across the 12 month period. The second is characterized by 32 patients (7.5%) with moderate pain intensity immediately after surgery which decreases markedly by 3 months and remains low at the 12 month follow-up. The final trajectory is characterized by 20 patients (8.4%) with moderate pain intensity immediately after surgery which persists at 12 months. Patients with moderate to severe postoperative pain intensity were much more likely to develop CPSP compared to patients with mild pain intensity. Initial pain intensity levels immediately following surgery as well as levels of pain catastrophizing at baseline were predicting pain trajectory membership. None of the surgical or anesthetic-related variables were significantly associated with pain trajectory membership.

CONCLUSION

Patients who undergo thoracic surgery can have postoperative pain that follows one of the three different types of trajectories. Higher levels of immediate postoperative pain and preoperative pain catastrophizing were associated with moderately severe CPSP.

Toward Understanding Movement-evoked Pain (MEP) and its Measurement: A Scoping Review

OBJECTIVE

Individuals with chronic pain conditions often report movement as exacerbating pain. An increasing number of researchers and clinicians have recognized the importance of measuring and distinguishing between movement-evoked pain (MEP) and pain at rest as an outcome. This scoping review maps the literature and describes MEP measurement techniques.

MATERIALS AND METHODS

The scoping review utilized 6 databases to identify original studies that targeted pain or movement-related outcomes. Our search returned 7322 articles that were screened by title and abstract by 2 reviewers. The inclusion criteria focused on the measurement of MEP before, during, and after movement tasks in adults with chronic pain. Studies of children below 18 years of age or with nonhuman animals, case studies, qualitative studies, book chapters, cancer-related pain, non-English language, and abstracts with no full publish text were excluded from the study.

RESULTS

Results from 38 studies revealed great variation in the measurement of MEP, while almost all of the studies did not provide an explicit conceptual or operational definition for MEP. In addition, studies collectively illuminated differences in MEP compared with rest pain, movement provocation methods, and pain intensity as the primary outcome.

DISCUSSION

These results have clinically significant and research implications. To advance the study of MEP, we offer that consistent terminology, standardized measurement (appropriate for pain type/population), and clear methodological processes be provided in research publications. On the basis of the findings, we have put forth a preliminary definition of MEP that may benefit from the continued scholarly dialog.

Subacute Pain Trajectories following major musculoskeletal surgery in adolescents: A Pilot Study

Background: Adolescents who undergo major surgery experience high rates of disabling acute and chronic postsurgical pain (CPSP). However, little is known about the subacute period when acute to chronic pain transition occurs.

Aims: The aims of this study were to examine feasibility of electronic daily monitoring of pain and opioid use in adolescents during the first 30 days at home following major surgery and identify target features of subacute pain curves associated with CPSP at 4 months.

Methods: Twenty-five youth (10–18 years) undergoing major musculoskeletal surgery reported daily pain severity, interference, and opioid use on the Brief Pain Inventory each evening for 30 days after hospital discharge to form short time series trajectories. At 4 months, youth reported on pain intensity and health-related quality of life. Characteristics of subacute pain severity and interference curves were compared by 4-month CPSP status.

Results: At 4 months, 20.8% of youth met criteria for CPSP. During the 30-day monitoring period, youth who went on to develop CPSP reported high pain severity on 45.9% of days compared to 2.9% of days in youth who recovered (P = 0.005) and high pain interference on 49.4% of days vs. 9.7% in youth who recovered (P = 0.01). Pain variability and rate of change were not significantly associated with CPSP in our pilot sample.

Conclusions: We found it feasible to collect daily pain data in youth recovering at home after major surgery. Pilot findings suggest that daily electronic monitoring may identify early recovery problems at home after surgery. Larger studies are needed to validate subacute pain trajectory features to identify risk for CPSP.

Factors associated with success and failure of patient-controlled oral analgesia after total hip and knee arthroplasty: a historical comparative cohort study

PURPOSE

Patient-controlled oral analgesia (PCOA) is a novel method of oral opioid administration using set doses of short-acting oral opioids self-administered by patients with a "lockout" period as part of a multimodal regimen. Failure of PCOA can result in severe postoperative pain necessitating use of intravenous patient-controlled analgesia (IV-PCA) with its potential complications. This study evaluated factors related to success or failure of PCOA following total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

We conducted a retrospective cohort study of all adults who underwent THA and TKA at our institution by extracting data from the proprietary database of our acute pain service. Patient, anesthetic, and surgical variables associated with PCOA failure defined as inadequate analgesia requiring conversion to IV-PCA within 24 hr following THA and TKA were evaluated. Univariable and multivariable logistic regression analyses were performed to identify predictors of PCOA failure.

RESULTS

Of the 926 patients who underwent THA or TKA (n = 411 and 515, respectively), 147 (15.9%) patients (67 THA and 80 TKA patients) had PCOA failure with moderate-to-severe pain. Multivariable regression analysis showed that PCOA failure occurred in those with younger age (adjusted odds ratio [aOR] per year of age, 0.97; 99% CI, 0.95 to 0.99; P < 0.001), preoperative chronic use of controlled-release opioids (aOR, 3.45; 99% CI, 1.60 to 7.35; P < 0.001), and with the use of general anesthesia vs spinal anesthesia (aOR, 2.86; 99% CI, 1.20 to 6.84; P = 0.002).

CONCLUSION

The use of PCOA provides adequate analgesia to a majority of patients undergoing THA and TKA. Factors predictive for PCOA failure should be considered when choosing the primary breakthrough analgesic modality following THA/TKA.

Trajectories in severe persistent pain after groin hernia repair: a retrospective analysis

Objectives

Severe persistent post-surgical pain (PPSP) remains a significant healthcare problem. In the third most common surgical procedure in the U.K., groin hernia repair, including 85,000 surgeries, estimated 1,500–3,000 patients will annually develop severe PPSP. While the trajectory of PPSP is generally considered a continuation of the acute post-surgery pain, recent data suggest the condition may develop with a delayed onset. This study evaluated pain-trajectories in a consecutive cohort referred from groin hernia repair-surgeons to a tertiary PPSP-center. Potential explanatory variables based on individual psychometric, sensory, and surgical profiles were analyzed.

Methods

Patients completed graphs on pain trajectories and questionnaires on neuropathic pain, pain-related functional assessments, and psychometrics. Surgical records and quantitative sensory testing profiles were obtained. Pain trajectories were normalized, and pre- and post-surgical segments were analyzed by a normalized area-under-the-curve (AUC) technique. Principal component analysis (PCA) was applied to the explanatory variables. Significant PCA-components were further examined using multiple logistic regression models.

Results

In 95 patients, the AUC identified groups of post-surgical pain trajectories (p<0.0001): group I (n=48), acute high-intensity pain progressing to PPSP; group II (n=28), delayed onset of PPSP; group III (n=7), repeat-surgery gradually inducing PPSP. Data from groups IV (n=3) and V (n=9) were not included in the statistical analysis due to small sample size and data heterogeneity, respectively. The PCA/logistic analyses indicated that neuropathic pain scores, composite pain scores, and pain-related functional assessments were explanatory variables for groups I and II.

Conclusions

Pain trajectories in PPSP after groin hernia repair are heterogeneous but can be classified into meaningful groups. Examination of pain trajectories, mirroring the transition from acute to severe persistent post-surgical pain, has the potential of uncovering clinically relevant pathophysiological mechanisms.

Psychosocial Predictors of Acute and Chronic Pain in Adolescents Undergoing Major Musculoskeletal Surgery

Acute and chronic pain delay recovery and impair outcomes after major pediatric surgery. Understanding unique risk factors for acute and chronic pain is critical to developing effective treatments for youth at risk. We aimed to identify adolescent and family psychosocial predictors of acute and chronic postsurgical pain after major surgery in adolescents. Participants included 119 youth age 10 to 18 years (M_age = 14.9; 78.2% white) undergoing major musculoskeletal surgery and their parents. Participants completed presurgery baseline questionnaires, with youth reporting on baseline pain, anxiety, depression, insomnia and sleep quality, and parents reporting on parental catastrophizing and family functioning. At baseline, 2-week, and 4-month postsurgery, youth completed 7 days of daily pain diaries and reported on health-related quality of life. Sequential logistic regression models examined presurgery predictors of acute and chronic postsurgical pain, defined as significant pain with impairment in health-related quality of life. Acute pain was experienced by 27.2% of youth at 2 weeks, while 19.8% of youth met criteria for chronic pain at 4 months. Baseline pain predicted acute pain (odds ratio [OR] = 1.96; 95% confidence interval [CI] = 1.32-2.90), while depressive symptoms (OR = 1.22; 95%CI = 1.01-1.47), and sleep quality (OR = 0.26; 95%CI = 0.08-0.83) predicted chronic pain. Tailored interventions need to be developed and incorporated into perioperative care to address risk factors for acute and chronic pain. PERSPECTIVE: Longitudinal results demonstrate adolescents' presurgery pain severity predicts acute postsurgical pain, while depressive symptoms and poor sleep quality predict chronic postsurgical pain. Tailored interventions should address separate risk factors for acute and chronic pain after adolescent surgery.

Predicting Acute Postoperative Pain Trajectories and Long-Term Outcomes of Adolescents after Spinal Fusion Surgery

Objectives

Acute pain trajectories are associated with long-term outcomes such as persistent pain and functional disability in adults. However, there are limited data on acute postoperative pain trajectories in the pediatric population. The aims of this study were to investigate acute postoperative pain trajectories, their predictors, and their impact on long- term outcomes in adolescents with idiopathic scoliosis.

Methods

We evaluated the preoperative pain intensity, use of analgesics, psychosocial measures and physical functioning of adolescents scheduled to undergo spinal fusion, and their average 6-hour self-reported pain intensity scores for their entire hospital stay. Six months after surgery, baseline variables were reassessed. We used growth mixture modeling to conduct acute postoperative pain trajectory analysis and to identify predictors of pain trajectories. Generalized linear models were conducted to determine whether acute pain trajectories predict long-term outcomes.

Results

One hundred and six patients were included in the best-fitted acute pain trajectory model that included four classes that differed in initial pain intensity and rates of change over time. Preoperative pain catastrophizer status and use of analgesics significantly predicted pain trajectory membership. Furthermore, at the 6-month follow-up, patients experiencing moderate-to-severe pain in the acute postoperative period were more likely to report higher levels of pain severity, use pain medication, and miss a greater number of school/work days due to back pain in the last three months. Discussion. Preoperative assessment and analyzing the progression of pain in the acute postoperative period can help identify those at risk of negative long-term outcomes after surgery.

Pediatric Chronic Postsurgical Pain And Functional Disability: A Prospective Study Of Risk Factors Up To One Year After Major Surgery

BACKGROUND

Chronic postsurgical pain (CPSP) is a surgical complication associated with increased functional disability, psychological distress, and economic costs. The aims of this paper were to prospectively: (1) examine the incidence of CPSP 6 and 12 months after pediatric major surgery; (2) identify pain intensity and pain unpleasantness trajectories before, and up to 12 months after, surgery; (3) identify pre-operative factors that predict pain trajectory group membership; and (4) identify predictors of 12-month functional disability.

METHODS

This study followed 265 children aged 8-17 years at four time points (pre-surgical [T0], in-hospital [T1], 6 [T2] and 12 [T3] months after surgery). Children and parents completed pain and psychological questionnaires. In-hospital physical activity was monitored using actigraphy.

RESULTS AND DISCUSSION

The incidence of moderate-to-severe CPSP at 6 and 12 months was 35% (95% CI 29.1% to 41.9%) and 38% (95% CI 32.4% to 45.1%), respectively. Three percent (95% CI 1.17% to 6.23%) and 4% (95% CI 1.45% to 6.55%) of children reported using opioids to manage pain at 6 and 12 months, respectively. Growth mixture modeling revealed a two-class trajectory model with a quadratic slope best fit the data for both pain intensity (Bayesian information criterion [BIC] = 3977.03) and pain unpleasantness (BIC = 3644.45) over the 12 months. Preoperative functional disability and cumulative in-hospital opioid consumption predicted pain intensity trajectories. Preoperative functional disability predicted pain unpleasantness trajectories. Preoperative functional disability (OR: 1.05, 95% CI: 1.01 to 1.09) and pain unpleasantness trajectories (OR: 2.59, 95% CI: 1.05 to 6.37) predicted 12-month moderate-to-severe functional disability.

CONCLUSION

Pre-surgical functional disability is the only factor that predicts both 12-month functional disability and the course of pain intensity and pain unpleasantness ratings over the 12-month period.

Identification of Functioning Domains in the Presurgical Period and Their Relationships with Opioid Use and Pain Catastrophizing

OBJECTIVES

The National Institutes of Health Patient-Reported Outcomes Measurement Information System (PROMIS) is a multidimensional screening system evaluating biopsychosocial factors affecting pain and functioning. Using a military sample, the current study 1) examined the structure and domains of the PROMIS, the Defense and Veterans Pain Rating Scale 2.0 (DVPRS), and the Pain Catastrophizing Scale (PCS) within a presurgical setting and 2) examined the relationship of these variables to pre- and postsurgical opioid use.

METHODS

This cross-sectional study included 279 adult patients scheduled for surgery at the Walter Reed National Military Medical Center and a validation sample of 79 additional patients from the Naval Medical Center, San Diego. PROMIS, DVPRS, PCS, and opioid use data were collected before surgery. Exploratory factor analysis and confirmatory factor analysis identified the latent structure for the measures. A structural equation model (SEM) examined their relationship to pre- and postsurgical opioid use.

RESULTS

Two latent factors represented Psychosocial Functioning (PROMIS Depression, PROMIS Anxiety, and PROMIS Social Isolation) and Pain Impact (DVPRS, PROMIS Pain Interference, PROMIS Physical Functioning). The remaining PROMIS scales did not load onto a single factor. In the SEM, the two latent factors and PCS were significantly related to pre- and postsurgical opioid use.

CONCLUSIONS

This study highlights the utility and relative ease of using a convenient multidimensional assessment in presurgical settings. Using such an assessment can help provide targeted interventions for individuals who may be at greatest risk for negative postsurgical outcomes.

Chronic postsurgical pain: From risk factor identification to multidisciplinary management at the Toronto General Hospital Transitional Pain Service

Background: Chronic postsurgical pain is a highly prevalent public health problem associated with substantial emotional, social, and economic costs. Aims: (1) To review the major risk factors for chronic postsurgical pain (CPSP); (2) to describe the implementation of the Transitional Pain Service (TPS) at the Toronto General Hospital, a multiprofessional, multimodal preventive approach to CPSP involving intensive, perioperative psychological, physical, and pharmacological management aimed at preventing and treating the factors that increase the risk of CPSP and related disability; and (3) to present recent empirical evidence for the efficacy of the TPS. Methods: The Toronto General Hospital TPS was specifically developed to target patients at high risk of developing CPSP. The major known risk factors for CPSP are perioperative pain, opioid use, and negative affect, including depression, anxiety, pain catastrophizing, and posttraumatic stress disorder-like symptoms. At-risk patients are identified early and provided comprehensive care by a multidisciplinary team consisting of pain physicians, advanced practice nurses, psychologists, and physical therapists. Results: Preliminary results from two nonrandomized, clinical practice-based trials indicate that TPS treatment is associated with improvements in pain, pain interference, pain catastrophizing, symptoms of anxiety and depression, and opioid use. Almost half of opioid-naïve patients and one in four opioid-experienced patients were opioid free by the 6-month point. Conclusions: These promising results suggest that the TPS benefits patients at risk of CPSP. A multicenter randomized controlled trial of the TPS in several Ontario hospitals is currently underway.

Longitudinal Trajectories of Pain and Function Improvement Following Total Knee Replacement

Objective

Up to 30% of patients experience persistent pain and functional limitations following total knee replacement (TKR). Rapid symptom relief in the early postoperative period may be linked to longer‐term outcome improvements. We sought to identify early improvement trajectories and to identify risk factors for suboptimal outcomes.

Methods

We used data from the Adding Value in Knee Arthroplasty (AViKA) Cohort study, a prospective longitudinal study of patients with knee osteoarthritis who underwent TKR. We assessed pain and function using the Western Ontario and McMaster Universities Arthritis Index (WOMAC). We used group‐based trajectory modeling to identify distinct patterns of pain and function improvement over 6 months. We assessed the association between these early improvement trajectories and 24‐month outcomes, including pain, function, and satisfaction.

Results

We analyzed data from 107 subjects. Mean baseline WOMAC pain and function scores were 42 (SD 17) and 44 (SD 15), respectively (0‐100; 100 = worst). We identified two pain‐improvement trajectories (suboptimal vs optimal improvement) and two function‐improvement trajectories (suboptimal vs optimal improvement). Greater pain catastrophizing, worse mental health status, and use of a supportive device prior to TKR were associated with being in a suboptimal trajectory. Recipients of TKR in the suboptimal trajectories had higher pain, high functional disability, and lower satisfaction at 24 months post‐TKR.

Conclusion

Patients with slower improvement over the first 6 months post‐TKR had worse outcomes at 24 months, suggesting that this early postoperative period may represent a window during which interventions aimed at speeding recovery may improve long‐term TKR outcomes.

Acute postoperative opioid consumption trajectories and long-term outcomes in pediatric patients after spine surgery

Background: The days following surgery are a critical period where the use of opioids predicts long-term outcomes in adults. It is currently unknown as to whether opioid consumption throughout the acute postoperative period is associated with long-term outcomes in pediatric patients. The aims of this study were to characterize opioid consumption trajectories in the acute postoperative period, identify predictors of trajectory membership and determine associations between opioid consumption trajectories and long-term patient outcomes.

Materials and methods: Medication use, pain and mental health status were assessed at baseline in adolescents with idiopathic scoliosis who were scheduled for spinal fusion surgery. Cumulative 6-hr opioid consumption was recorded for up to 5 days after spinal surgery. At 6 months after surgery, medication use, pain and functional activity were evaluated. Growth mixture modeling was used to identify opioid trajectories.

Results: One hundred and six patients were included in the study. Mean cumulative 6-hr opioid consumption in the acute postoperative period was 13.23±5.20 mg/kg. The model with the best fit contained 5 acute postoperative trajectories and a quadratic term (AIC =6703.26, BIC =6767.19). Two types of patient behaviors were identified: high opioid consumers (trajectories 4 and 5) and low opioid consumers (trajectories 1, 2 and 3). Intraoperative intrathecal morphine dose was a predictor of trajectory membership (p=0.0498). Opioid consumption during the acute postoperative period was not significantly associated with pain, functional activity or pain medication use at 6 months after surgery.

Conclusion: In pediatric patients, intraoperative intrathecal morphine dose predicts opioid consumption in the acute postoperative period. Importantly, opioid consumption during this period does not affect long-term outcomes in pediatric patients after a spine surgery.

Prediction of persistent post-surgery pain by preoperative cold pain sensitivity: biomarker development with machine-learning-derived analysis

Background

To prevent persistent post-surgery pain, early identification of patients at high risk is a clinical need. Supervised machine-learning techniques were used to test how accurately the patients' performance in a preoperatively performed tonic cold pain test could predict persistent post-surgery pain.

Methods

We analysed 763 patients from a cohort of 900 women who were treated for breast cancer, of whom 61 patients had developed signs of persistent pain during three yr of follow-up. Preoperatively, all patients underwent a cold pain test (immersion of the hand into a water bath at 2-4 °C). The patients rated the pain intensity using a numerical ratings scale (NRS) from 0 to 10. Supervised machine-learning techniques were used to construct a classifier that could predict patients at risk of persistent pain.

Results

Whether or not a patient rated the pain intensity at NRS=10 within less than 45 s during the cold water immersion test provided a negative predictive value of 94.4% to assign a patient to the "persistent pain" group. If NRS=10 was never reached during the cold test, the predictive value for not developing persistent pain was almost 97%. However, a low negative predictive value of 10% implied a high false positive rate.

Conclusions

Results provide a robust exclusion of persistent pain in women with an accuracy of 94.4%. Moreover, results provide further support for the hypothesis that the endogenous pain inhibitory system may play an important role in the process of pain becoming persistent.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

Factors Associated With Acute Pain Estimation, Postoperative Pain Resolution, Opioid Cessation, and Recovery: Secondary Analysis of a Randomized Clinical Trial

Importance

Acute postoperative pain is associated with the development of persistent postsurgical pain, but it is unclear which aspect is most estimable.

Objective

To identify patient clusters based on acute pain trajectories, preoperative psychosocial characteristics associated with the high-risk cluster, and the best acute pain predictor of remote outcomes.

Design, Setting, and Participants

A secondary analysis of the Stanford Accelerated Recovery Trial randomized, double-blind clinical trial was conducted at a single-center, tertiary, referral teaching hospital. A total of 422 participants scheduled for thoracotomy, video-assisted thoracoscopic surgery, total hip replacement, total knee replacement, mastectomy, breast lumpectomy, hand surgery, carpal tunnel surgery, knee arthroscopy, shoulder arthroplasty, or shoulder arthroscopy were enrolled between May 25, 2010, and July 25, 2014. Data analysis was performed from January 1 to August 1, 2018.

Interventions

Patients were randomized to receive gabapentin (1200 mg, preoperatively, and 600 mg, 3 times a day postoperatively) or active placebo (lorazepam, 0.5 mg preoperatively, inactive placebo postoperatively) for 72 hours.

Main Outcomes and Measures

A modified Brief Pain Inventory prospectively captured 3 surgical site pain outcomes: average pain and worst pain intensity over the past 24 hours, and current pain intensity. Within each category, acute pain trajectories (first 10 postoperative pain scores) were compared using a k-means clustering algorithm. Fifteen descriptors of acute pain were compared as predictors of remote postoperative pain resolution, opioid cessation, and full recovery.

Results

Of the 422 patients enrolled, 371 patients (≤10% missing pain scores) were included in the analysis. Of these, 146 (39.4%) were men; mean (SD) age was 56.67 (11.70) years. Two clusters were identified within each trajectory category. The high pain cluster of the average pain trajectory significantly predicted prolonged pain (hazard ratio [HR], 0.63; 95% CI, 0.50-0.80; P < .001) and delayed opioid cessation (HR, 0.52; 95% CI, 0.41-0.67; P < .001) but was not a predictor of time to recovery in Cox proportional hazards regression (HR, 0.89; 95% CI, 0.69-1.14; P = .89). Preoperative risk factors for categorization to the high average pain cluster included female sex (adjusted relative risk [ARR], 1.36; 95% CI, 1.08-1.70; P = .008), elevated preoperative pain (ARR, 1.11; 95% CI, 1.07-1.15; P < .001), a history of alcohol or drug abuse treatment (ARR, 1.90; 95% CI, 1.42-2.53; P < .001), and receiving active placebo (ARR, 1.27; 95% CI, 1.03-1.56; P = .03). Worst pain reported on postoperative day 10 was the best predictor of time to pain resolution (HR, 0.83; 95% CI, 0.78-0.87; P < .001), opioid cessation (HR, 0.84; 95% CI, 0.80-0.89; P < .001), and complete surgical recovery (HR, 0.91; 95% CI, 0.86-0.96; P < .001).

Conclusions and Relevance

This study has shown a possible uniform predictor of remote postoperative pain, opioid use, and recovery that can be easily assessed. Future work is needed to replicate these findings.

Trial Registration

ClinicalTrials.gov Identifier: NCT01067144.

In-hospital opioid consumption, but not pain intensity scores, predicts 6-month levels of pain catastrophizing following hepatic resection: A trajectory analysis

BACKGROUND

The study aims were to model acute pain intensity and opioid consumption trajectories up to 72 hr after open hepatic resection, identify predictors of trajectory membership and examine the association between trajectory memberships and 6-month pain and psychological outcomes. This is a long-term analysis of a published randomized controlled trial on the impact of medial open transversus abdominis plane catheters on post-operative outcomes.

METHODS

A total of 152 patients (89 males; mean age 63.0 [range: 54-72]) completed questionnaires on pain and related characteristics pre-operatively and 6 months post-operatively. Total opioid use was recorded several times over a 72-hr period while self-reported pain intensity scores were collected multiple times until hospital discharge. Analyses were carried out using growth mixture modelling, logistic regression and general linear models.

RESULTS

Both pain intensity and opioid consumption showed that a four-trajectory model best fits the data. Patients in the lowest opioid consumption trajectory were more likely to be classified in the constant mild pain intensity trajectory. Age and baseline levels of anxiety significantly predicted opioid trajectory membership while baseline depressive symptoms significantly predicted pain intensity trajectory membership. Patients in the two highest opioid consumption trajectories reported significantly higher levels of pain catastrophizing at 6 months compared to patients in the other 3 trajectories (all p < 0.05).

CONCLUSION

High consumption of opioids after surgery is associated with higher levels of pain catastrophizing 6 months later. Identification of patients within these trajectories may lead to the development of early interventions targeted to high risk individuals.

SIGNIFICANCE

Differences in initial levels of opioid consumption and rates of change in opioid consumption shortly after surgery can help predict long-term psychological responses to pain. Identifying key characteristics associated with initial opioid consumption can lead to the development of cost-effective early interventions targeted to high risk individuals.

Paradoxical Sleep Deprivation Aggravates and Prolongs Incision-Induced Pain Hypersensitivity via BDNF Signaling-Mediated Descending Facilitation in Rats

The mechanisms underlying the pronociceptive effect of paradoxical sleep deprivation (PSD) are not fully established. The modulation of BDNF signaling-mediated descending facilitation from the rostral ventromedial medulla (RVM) of brain stem has been demonstrated in persistent pain models of inflammatory pain, but not in incisional pain model. Recent study has shown that PSD increases the expression of brain-derived neurotrophic factor (BDNF) in the brainstem structure. Therefore, in the current study, we asked whether the BDNF signaling-mediated descending facilitation was involved in the PSD-induced pronociceptive effect on incisional pain and delay the recovery period of postoperative pain in rats. Our results found that a preoperative 24 h PSD significantly aggravated the pain hypersensitivity after incision and prolonged the duration of postoperative pain. The lesions of ipsilateral dorsolateral funiculus partly reversed the PSD-induced pronociceptive effect on incisional pain. Interestingly, the 24 h PSD, but not incision significantly enhanced the levels of BDNF protein expression in the RVM areas of rats. Furthermore, at 1 day or 4 days after incision, intra-RVM microinjection of a BDNF antibody partly reversed the PSD-induced pronociceptive effects in incisional rats, while it did not change the cumulative pain scores and paw withdrawal thresholds in rats receiving only plantar incision. These findings suggest that the preoperative PSD may aggravate and prolong the incision-induced pain hypersensitivity via BDNF signaling-mediated descending facilitation.

Day-to-day experience in resolution of pain after surgery

We know little about the individual pain experience of patients recovering from surgery in the first weeks after hospital discharge. Here, we examine individual differences in the day-to-day experience after 2 major surgeries: lower limb total major joint arthroplasty (TJA) and cesarean delivery (CD). Fifty-five TJA patients and 157 CD patients were recruited to complete questionnaires and record their daily pain experiences after surgery. After hospital discharge, patients recorded their pain intensity once daily for 60 days (CD) or twice daily for 2 weeks, once daily for 2 weeks, weekly for 8 weeks, and monthly for 3 months (TJA). Pain scores were modeled using growth curve and Bayesian change-point models. Individual differences in the model fits were examined for evidence of day-to-day differences in pain. A log time model was the simplest model that fit the data, but examination of the residuals revealed high autocorrelation representing misspecification. A change-point model fit the data better and revealed that the form of recovery fundamentally changed between days 10 and 21 after surgery. These data add meaningfully to our understanding of recovery from pain after surgery by extending the period of frequent observations a few days after surgery to a 2-month period. These high time resolution data suggest that there is a typical experience of pain resolution after surgery, but that meaningful subpopulations of experience may exist. They also indicate that a transition occurs within 1 month after surgery from 1 pattern of change in pain over time to another.

A comparison of predictors and intensity of acute postsurgical pain in patients undergoing total hip and knee arthroplasty

Background

Acute pain is an expected result after surgery. Nevertheless, when not appropriately controlled, acute pain has a very negative impact on individual clinical outcomes, impairing healing and recovery, and has clear consequences on health care system costs. Augmenting knowledge on predictors and potentially modifiable determinants of acute postsurgical pain can facilitate early identification of and intervention in patients at risk. However, only a few studies have examined and compared acute pain after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The aim of this study was to compare THA and TKA in acute postsurgical pain intensity and its predictors.

Methods

A consecutive sample of 124 patients with osteoarthritis (64 undergoing THA and 60 TKA) was assessed 24 hours before (T1) and 48 hours after (T2) surgery. Demographic, clinical, and psychological factors were assessed at T1, and acute postsurgical pain experience was examined at T2. Additionally, the same hierarchical regression analysis was performed separately for each arthroplasty type.

Results

TKA patients reported higher levels of acute postsurgical pain compared with THA (t=8.490, p=0.004, d=0.527, 95% confidence interval, 0.196–0.878). In the final THA predictive model, presurgical pain was the only variable approaching significant results (t[57]=1.746, β=0.254, p=0.086). In the final TKA predictive model, optimism was the only predictor of pain (t[51]=−2.518, β=−0.339, p=0.015), with emotional representation (t[51]=1.895, β=0.254, p=0.064) presenting a trend toward significance.

Conclusion

The current study is the first examining THA and TKA differences on acute postsurgical pain intensity and its predictors using a multivariate approach. Results from this study could prove useful for the design of distinct interventions targeting acute postsurgical pain management depending on whether the site of arthroplasty is the hip or the knee. Finally, the current results also support the argument that these two surgeries, at least with regard to acute pain, should be approached separately.