Postoperative pain trajectories in chronic pain patients undergoing surgery: the effects of chronic opioid pharmacotherapy on acute pain

Preoperative Chronic Opioid Therapy: A Risk Factor for Complications, Readmission, Continued Opioid Use and Increased Costs After One- and Two-Level Posterior Lumbar Fusion

STUDY DESIGN

Retrospective, economic analysis.

OBJECTIVE

To study patient profile associated with preoperative chronic opioid therapy (COT), and study COT as a risk factor for 90-day complications, emergency department (ED) visits, and readmission after primary one- to two-level posterior lumbar fusion (PLF) for degenerative spine disease. We also evaluated associated costs, risk factors, and adverse events related to long-term postoperative opioid use.

SUMMARY OF BACKGROUND DATA

Chronic opioid use is associated with poor outcomes and dependence after spine surgery. Risk factors, complications, readmissions, adverse events, and costs associated with COT in patients undergoing lumbar fusion are not entirely known. As providers look to reduce healthcare costs and improve outcomes, identification of modifiable risk factors is important.

METHODS

Commercial insurance data from 2007 to Q3-2015 was used to study preoperative opioid use in patients undergoing primary one- to two-level PLF. Ninety-day complications, ED visits, readmissions, 1-year adverse events, and associated costs have been described. Multiple-variable regression analyses were done to study preoperative COT patient profile and opioid use as a risk factor for complications and adverse events.

RESULTS

A total of 24,610 patients with a mean age of 65.6 ± 11.5 years were included. Five thousand five hundred (22.3%) patients had documented opioid use for more than 6 months before surgery, and 87.4% of these had continued long-term use postoperatively. On adjusted analysis, preoperative COT was found to be a risk factor for 90-day wound complications, pain diagnoses, ED visits, readmission, and continued use postoperatively. Postspinal fusion long-term opioid users had an increased utilization of epidural/facet joint injections, risk for revision fusion, and increased incidence of new onset constipation within 1 year postsurgery. The cost associated with increase resource use in these patients has been reported.

CONCLUSION

Preoperative COT is a modifiable risk factor for complications, readmission, adverse events, and increased costs after one- or two-level PLF.

LEVEL OF EVIDENCE

3.

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.

Prospective, Observational Study of Opioid Use After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To provide estimates of postoperative opioid use after hip arthroscopy for femoroacetabular impingement (FAI) syndrome and to identify risk factors for increased postoperative opioid use.

METHODS

All patients aged at least 18 years who were undergoing hip arthroscopy for FAI syndrome performed by 1 of 2 hip-preservation surgeons between November 2015 and August 2016 were eligible for inclusion in this study. Target minimum enrollment was set at 30 patients per surgeon based on an a priori sample size calculation. Enrolled patients completed the International Hip Outcome Tool, visual analog pain scale, Pain Catastrophizing Scale, abbreviated Patient Health Questionnaire, and questions regarding demographic characteristics and opioid and anti-inflammatory use. Opioid consumption was assessed through pill counting at 2- and 6-week postoperative appointments. Of 80 patients enrolled, 67 had complete 2- and 6-week opioid use data. Patient and operative factors were correlated with outcomes in multivariate models.

RESULTS

Opioid use in the 2 weeks before surgery was significantly associated with higher postoperative opioid use at 2 weeks postoperatively (253.8 additional oral morphine equivalents [OMEs]; 95% confidence interval [CI], 171.2-336.5 additional OMEs; P < .0001; n = 73) and 6 weeks postoperatively (385.3 additional OMEs; 95% CI, 241.6-529.0 additional OMEs; P < .0001; n = 67). By 6 weeks postoperatively, 41 of 52 patients (79%) without opioid use in the 2 weeks before surgery used 30 or fewer 5-mg oxycodone pills compared with only 2 of 15 patients (13%) with preoperative use (odds ratio, 24.9; 95% CI, 4.2-148.5; P < .0001).

CONCLUSIONS

Among patients undergoing hip arthroscopy for FAI syndrome, any opioid use in the 2 weeks preceding surgery was the strongest predictor of opioid use after hip arthroscopy. The impact of preoperative opioid use far exceeded the impact of other baseline patient and operative factors. Assessment of preoperative opioid use could be an important factor in guiding postoperative opioid prescribing.

LEVEL OF EVIDENCE

Level II, prospective observational study.

Psychosocial Stress Delays Recovery of Postoperative Pain Following Incisional Surgery in the Rat

Psychosocial factors such as anxiety, depression and catastrophizing, commonly associated with established chronic pain, also may be associated with an increased risk of chronic postsurgical pain (CPSP) when present preoperatively. We used a repeat social defeat (RSD) paradigm to induce psychosocial stress in rodents prior to incisional surgery of the paw. Mixed effects growth curve models were utilized to examine resolution of mechanical hypersensitivity in rats for four weeks following surgery. Eight days following surgery, immunohistochemistry was conducted to examine glial activation as well as evoked neuronal activation in the spinal cord. Here we document that RSD resulted in reduced weight gain and increased depressive symptoms prior to surgery. Rats exposed to RSD displayed delayed resolution of mechanical hypersensitivity in the ipsilateral paw following surgery compared to non-defeated rats. Prior exposure to RSD significantly increased microglial activation and neuronal sensitization (pERK-IR) within the ipsilateral spinal cord. In conclusion, we found that chronic social stress alters the neurobiological response to surgical injury, resulting in slowed recovery. This model maybe useful for future interventional studies examining the mechanistic interactions between depression and risk of CPSP.

Pre-optimization of spinal surgery patients: Development of a neurosurgical enhanced recovery after surgery (ERAS) protocol

OBJECTIVE

Despite surgical, technological, medical, and anesthetic improvements, patient outcomes following elective neurosurgical procedures can be associated with high morbidity. Enhanced recovery after surgery (ERAS) protocols are multimodal care pathways designed to optimize patient outcomes by addressing pre-, peri-, and post-operative factors. Despite significant data suggesting improved patient outcomes with the adoption of these pathways, development and implementation has been limited in the neurosurgical population.

METHODS/RESULTS

This study protocol was designed to establish the feasibility of a randomized controlled trial to assess the efficacy of implementation of an ERAS protocol on the improvement of clinical and patient reported outcomes and patient satisfaction scores in an elective inpatient spine surgery population. Neurosurgical patients undergoing spinal surgery will be recruited and randomly allocated to one of two treatment arms: ERAS protocol (experimental group) or hospital standard (control group). The experimental group will undergo interventions at the pre-, peri-, and post-operative time points, which are exclusive to this group as compared to the hospital standard group.

CONCLUSIONS

The present proposal aims to provide supporting data for the application of these specific ERAS components in the spine surgery population and provide rationale/justification of this type of care pathway. This study will help inform the design of a future multi-institutional, randomized controlled trial.

RESULTS

of this study will guide further efforts to limit post-operative morbidity in patients undergoing elective spinal surgery and to highlight the impact of ERAS care pathways in improving patient reported outcomes and satisfaction.

Rationale for and approach to preoperative opioid weaning: a preoperative optimization protocol

The practice of chronic opioid prescription for chronic non-cancer pain has come under considerable scrutiny within the past several years as mounting evidence reveals a generally unfavorable risk to benefit ratio and the nation reels from the grim mortality statistics associated with the opioid epidemic. Patients struggling with chronic pain tend to use opioids and also seek out operative intervention for their complaints, which combination may be leading to increased postoperative "acute-on-chronic" pain and fueling worsened chronic pain and opioid dependence. Besides worsened postoperative pain, a growing body of literature, reviewed herein, indicates that preoperative opioid use is associated with significantly worsened surgical outcomes, and severely increased financial drain on an already severely overburdened healthcare budget. Conversely, there is evidence that preoperative opioid reduction may result in substantial improvements in outcome. In the era of accountable care, efforts such as the Enhanced Recovery After Surgery (ERAS) protocol have been introduced in an attempt to standardize and facilitate evidence-based perioperative interventions to optimize surgical outcomes. We propose that addressing preoperative opioid reduction as part of a targeted optimization approach for chronic pain patients seeking surgery is not only logical but mandatory given the stakes involved. Simple opioid reduction/abstinence however is not likely to occur in the absence of provision of viable and palatable alternatives to managing pain, which will require a strong focus upon reducing pain catastrophization and bolstering self-efficacy and resilience. In response to a call from our surgical community toward that end, we have developed a simple and easy-to-implement outpatient preoperative optimization program focusing on gentle opioid weaning/elimination as well as a few other high-yield areas of intervention, requiring a minimum of resources.

Leading the Way to Solutions to the Opioid Epidemic: AOA Critical Issues

BACKGROUND

In the past 2 decades, overdoses and deaths from prescription opioids have reached epidemic proportions in the United States. The widespread use of opioids complicates management of the orthopaedic surgery patient in the acute and chronic settings. Orthopaedic surgeons are some of the top prescribers of opioids in the complex setting of chronic use, abuse, and diversion.

METHODS

The literature regarding the basic science of pharmacologic options for pain management (e.g., opioids and nonsteroidal anti-inflammatory drugs), the impact of strategies on bone and soft-tissue healing, and pain relief are summarized as they relate to the management of orthopaedic injuries and conditions. Additionally, a section on designing solutions to address the current opioid crisis is presented.

RESULTS

The mechanism of action of different classes of analgesic medications is discussed, as well as the basic scientific evidence regarding the impact of narcotic and nonnarcotic analgesic medications on bone-healing and on other organ systems. Differences between pain and nociception, various treatment strategies, and clinical comparisons of the effectiveness of various analgesics compared with opioids are summarized. Finally, options for addressing the opioid crisis, including the description of a large system-wide intervention to impact prescriber behavior at the point of care using health-information solutions, are presented.

CONCLUSIONS

Orthopaedic leaders, armed with information and strategies, can help lead the way to solutions to the opioid epidemic in their respective communities, institutions, and subspecialty societies. Through leadership and education, orthopaedic surgeons can help shape the solution for this critical public health issue.

Is There a Preoperative Morphine Equianalgesic Dose that Predicts Ability to Achieve a Clinically Meaningful Improvement Following Spine Surgery?

BACKGROUND

Preoperative opioid use is widespread and associated with worse patient-reported outcomes following spine surgery.

OBJECTIVE

To calculate a threshold preoperative morphine equianalgesic (MEA) dose beyond which patients are less likely to achieve the minimum clinically important difference (MCID) following elective surgery for degenerative spine disease.

METHODS

The study included 543 cervical and 1293 lumbar patients. Neck Disability Index and Oswestry Disability Index scores were collected at baseline and 12 mo postoperatively. Preoperative MEA doses were calculated retrospectively. Multivariate logistic regression was then performed to determine the relationship between MEA dose and the odds of achieving MCID. As a part of this regression, Bayesian inference and Markov Chain Monte Carlo methods were used to estimate the values of inflection points (or “thresholds”) in MEA.

RESULTS

Overall, 1020 (55.5%) patients used preoperative opioids. A total of 50.3% of cervical and 61.9% of lumbar patients achieved MCID. The final logistic regression model demonstrated that MCID achievement decreased significantly when mean preoperative MEA dose exceeded 47.8 mg/d, with a 95% credible interval of 29.0 to 60.0 mg/d.

CONCLUSION

Minimum and maximum MEA doses exist, between which increasing opioid dose is associated with decreased ability to achieve clinically meaningful improvement following spine surgery. Patients with preoperative MEA dose exceeding 29 mg/d, the lower limit of the 95% credible interval for the mean MEA dose above which patients exhibit significantly decreased achievement of MCID, may be considered for preoperative opioid weaning.

'Why me?' The problem of chronic pain after surgery

Chronic postsurgical pain (CPSP) has become a health priority and is scheduled to be included in the upcoming version of the International Classification of Diseases, 11th Revision (ICD-11). Recent studies on CPSP show unchanged prevalence despite progress made in fundamental research about underlying pathophysiological mechanisms. Nevertheless, clinical research has allowed better understanding of some CPSP aspects such as the development of neuropathic CPSP. Actually, some improvements are ongoing such as a refined definition and the assessment of CPSP in vulnerable populations, for example, paediatric patients. Pain after surgery, its resolution or its transition to CPSP is a dynamic process that reinforces the necessity of longitudinal assessment and management. In other words, CPSP can be called 'perioperative medicine'.

Acute pain management in patients with drug dependence syndrome

Managing patients with dependence requires knowledge of pharmacology; an understanding of the diagnosis of dependence and recognition of withdrawal; skills in communication and collaborative working; and a nonjudgmental, empathic attitude.

Decreasing Opioid Utilization in Rehabilitation Patients Using a Clinical Nurse Specialist Pain Consultant Program

OBJECTIVE

To investigate whether access to a clinical nurse specialist (CNS) with expertise in pain management will result in more rapid decline in opioid use across the rehabilitation hospitalization.

DESIGN

Retrospective chart review of patients discharged during 6 months prior to and 6 months after introduction of the CNS role.

SETTING

Not-for-profit 98-bed community inpatient rehabilitation hospital.

PARTICIPANTS

Two population-based samples of adult, inpatient rehabilitation patients (N=72) with daily opioid use ≥30mg morphine equivalent dose (MED) per day on admission and length of stay ≥24 days.

INTERVENTIONS

Implementation of a CNS pain consult program.

MAIN OUTCOME MEASURES

Change in average daily opioid use (milligrams of MED per day), measured at admission, week 1, week 2, and week 3.

RESULTS

Linear mixed modeling was used to estimate individual and group average opioid trajectories, including individual patient intercepts (opioid use at admission) and slopes (change in opioid use over time). There was a significant interaction between group and time (b=5.75, t=2.52, P<.01), indicating faster change in opioid use for the CNS group (quadratic slope, -5.91) compared with the no CNS group (quadratic slope, -.16). Quadratic change in the CNS group reflected an initial increase in opioid use from admission to week 1, followed by a steady decline. Conversely, there was virtually no change in the no CNS group. Random effects revealed considerable variability in opioid trajectories across patients.

CONCLUSIONS

Addition of a CNS pain consultant program to an inpatient rehabilitation hospital supported a distinct pattern of opioid tapering that promoted more rapid titration of daily opioid use across the rehabilitation hospitalization.

Psychosocial Risk Factors for Postoperative Pain in Ankle and Hindfoot Reconstruction

BACKGROUND

The purpose of this study was to examine factors associated with pain after elective ankle and hindfoot reconstruction.

METHODS

Patients who underwent major ankle or hindfoot reconstruction over a 3-year period were identified. Retrospective chart review determined patient demographics, comorbidities, surgeries, tobacco, alcohol, and narcotic use, chronic pain, and mood disorders. Primary outcomes were cumulative amount of narcotic prescribed (morphine milligram equivalent dose) in the initial 90-day postoperative period, beyond 90 days, and visual analog pain score (VAS) at a minimum of 1-year follow-up. One hundred thirty-two patients (139 operations) met the inclusion criteria.

RESULTS

The average narcotic amount prescribed in the initial 90 days after surgery was 1711 mg (morphine equivalent), and narcotic prescriptions were required after 52 surgeries (35%) past 90 days. Preoperative narcotic use (P < .01), chronic pain disorder (P = .02), and mood disorder (P < .01) were significant risk factors for continued narcotic use past 90 days. Tobacco use (P = .01) and chronic pain disorder (P < .01) also were significant risk factors for increased initial postoperative narcotic use. The average VAS score in 91 patients at an average of 2.7-year follow-up was 2.1. Mood disorder was a risk factor for increased VAS (P < .01). No other associations were noted.

CONCLUSION

Patients being treated for chronic pain, diagnosed with a mood disorder, taking any amount of narcotics preoperatively, or using tobacco products had a statistically significant increased risk for pain postoperatively. The presence of risk factors should prompt physicians to discuss pain management strategies before surgery.

LEVEL OF EVIDENCE

Level III, comparative series.

Challenges of pain control and the role of the ambulatory pain specialist in the outpatient surgery setting

Ambulatory surgery is on the rise, with an unmet need for optimum pain control in ambulatory surgery centers worldwide. It is important that there is a proportionate increase in the availability of acute pain-management services to match the rapid rise of clinical patient load with pain issues in the ambulatory surgery setting. Focus on ambulatory pain control with its special challenges is vital to achieve optimum pain control and prevent morbidity and mortality. Management of perioperative pain in the ambulatory surgery setting is becoming increasingly complex, and requires the employment of a multimodal approach and interventions facilitated by ambulatory surgery pain specialists, which is a new concept. A focused ambulatory pain specialist on site at each ambulatory surgery center, in addition to providing safe anesthesia, could intervene early once problematic pain issues are recognized, thus preventing emergency room visits, as well as readmissions for uncontrolled pain. This paper reviews methods of acute-pain management in the ambulatory setting with risk stratification, the utilization of multimodal interventions, including pharmacological and nonpharmacological options, opioids, nonopioids, and various routes with the goal of preventing delayed discharge and unexpected hospital admissions after ambulatory surgery. Continued research and investigation in the area of pain management with outcome studies in acute surgically inflicted pain in patients with underlying chronic pain treated with opioids and the pattern and predictive factors for pain in the ambulatory surgical setting is needed.

Hyperalgesia induced by low-dose opioid treatment before orthopaedic surgery: An observational case-control study

BACKGROUND

Chronic pain and opioid consumption may trigger diffuse hyperalgesia, but their relative contributions to pain vulnerability remain unclear.

OBJECTIVES

To assess preoperative opioid-induced hyperalgesia and its postoperative clinical consequences in patients with chronic pain scheduled for orthopaedic surgery.

DESIGN

A prospective observational study.

SETTINGS

Raymond Poincare teaching hospital.

PATIENTS

Adults with or without long-term opioid treatment, scheduled for orthopaedic surgery.

PRIMARY OUTCOME MEASURE

Preoperative hyperalgesia was assessed with eight quantitative sensory tests, in a pain-free zone.

SECONDARY OUTCOME MEASURES

Postoperative morphine consumption and pain intensity were evaluated using a numerical rating scale (NRS) in the recovery room and during the first 72 h.

RESULTS

We analysed results from 68 patients (28 opioid-treated patients and 40 controls). Mean daily opioid consumption was 42 ± 25 mg of morphine equivalent. The opioid-treated group displayed significantly higher levels of preoperative hyperalgesia in three tests: heat tolerance threshold (47.1°C vs. 48.4°C; P = 0.045), duration of tolerance to a 47°C stimulus (40.2 vs. 51.1 s; P = 0.03) and mechanical temporal summation [1.79 vs. 1.02 (ΔNRS10-1); P = 0.036]. Patients in the opioid-treated group consumed more morphine (19.1 vs. 9.38 mg; P = 0.001), had a higher pain intensity (7.6 vs. 5.5; P = 0.001) in the recovery room and a higher cumulative morphine dose at 72 h (39.8 vs. 25.6 mg; P = 0.02).

CONCLUSION

Chronic pain patients treated with low doses of opioid had hyperalgesia before surgery. These results highlight the need to personalise the management of patients treated with opioids before surgery.

TRIAL REGISTRATION

ID-RCB 2011-A00304-37.

Effect of Preoperative Inflammatory Status and Comorbidities on Pain Resolution and Persistent Postsurgical Pain after Inguinal Hernia Repair

Poor acute pain control and inflammation are important risk factors for Persistent Postsurgical Pain (PPSP). The aim of the study is to investigate, in the context of a prospective cohort of patients undergoing hernia repair, potential risk factors for PPSP. Data about BMI, anxious-depressive disorders, neutrophil-tolymphocyte ratio (NLR), proinflammatory medical comorbidities were collected. An analysis for correlation between comorbidities and PPSP was performed in those patients experiencing chronic pain at 3 months after surgery. Tramadol resulted less effective in pain at movement in patients with a proinflammatory status. Preoperative hypertension and NLR > 4 were correlated with PPSP intensity. Regional anesthesia was significantly protective on PPSP when associated with ketorolac. Patients with pain at 1 month were significantly more prone to develop PPSP at 3 months. NSAIDs or weak opioids are equally effective on acute pain and on PPSP development after IHR, but Ketorolac has better profile in patients with inflammatory background or undergoing regional anesthesia. Drug choice should be based on their potential side effects, patient's profile (comorbidities, preoperative inflammation, and hypertension), and type of anesthesia. Close monitoring is necessary to early detect pain conditions more prone to progress to a chronic syndrome.

Ambulatory and diary methods can facilitate the measurement of patient-reported outcomes

PURPOSE

Ambulatory and diary methods of self-reported symptoms and well-being have received increasing interest in recent years. These methods are a valuable addition to traditional strategies for the assessment of patient-reported outcomes (PROs) in that they capture patients' recent symptom experiences repeatedly in their natural environments. In this article, we review ways that incorporating diary methods into PRO measurement can facilitate research on quality of life.

METHODS

Several diary methods are currently available, and they include "real-time" (Ecological Momentary Assessment) and "near-real-time" (end-of-day assessments, Day Reconstruction Method) formats. We identify the key benefits of these methods for PRO research.

RESULTS

(1) In validity testing, diary assessments can serve as a standard for evaluating the ecological validity and for identifying recall biases of PRO instruments with longer-term recall formats. (2) In research and clinical settings, diaries have the ability to closely capture variations and dynamic changes in quality of life that are difficult or not possible to obtain from traditional PRO assessments. (3) In test construction, repeated diary assessments can expand understanding of the measurement characteristics (e.g., reliability, dimensionality) of PROs in that parameters for differences between people can be compared with those for variation within people.

CONCLUSIONS

Diary assessment strategies can enrich the repertoire of PRO assessment tools and enhance the measurement of patients' quality of life.

Increased Preoperative Narcotic Use and Its Association With Postoperative Complications and Length of Hospital Stay in Patients Undergoing Spine Surgery

STUDY DESIGN

Prospective cohort analysis.

OBJECTIVE

To assess the effect of preoperative narcotic use on the incidence of 30- and 90-day postoperative complications, as well as length of hospital stay (LOS) in patients undergoing spine surgery.

SUMMARY OF BACKGROUND DATA

Previous work has associated an increased incidence of complications and length of stay following surgery in patients with increased preoperative narcotic use. Despite this and recent national attention highlighting the negative effects of narcotics, they remain commonly used for the management of pain in patients undergoing spine surgery.

MATERIALS AND METHODS

A total of 583 patients undergoing spine surgery for a structural lesion were evaluated. Self-reported preoperative narcotic consumption was obtained and converted to morphine equivalents at the initial preoperative visit. LOS was recorded upon discharge and presence/type of a postoperative complication within 30/90 days was obtained. A multivariable logistic and linear regression analysis was performed for the incidence of complications and length of stay controlling for clinically important covariates.

RESULTS

Narcotic use was not associated with 30- or 90-day complications; however, smoking status was significantly associated with 30-day complications. Increased preoperative narcotic use was significantly associated with increased LOS, as was age, type of surgery, and depression.

CONCLUSIONS

Increased preoperative narcotic use and depression are associated with increased LOS in patients undergoing spine surgery. We calculated that for every 100 morphine equivalents a patient is taking preoperatively; their stay is extended 1.1 days. Narcotic use was not associated with 30- or 90-day postoperative complications. As reimbursement is bundled before surgery, providing interventions for patients with treatable causes for increased length of stay can save cost overall.

Preoperative narcotic utilization: accuracy of patient self-reporting and its association with postoperative narcotic consumption

OBJECT

Little is known about the accuracy of reporting of preoperative narcotic utilization in spinal surgery. As such, the purpose of this study is to compare postoperative narcotic consumption between preoperative narcotic utilizers who do and do not accurately self-report preoperative utilization.

METHODS

Patients who underwent anterior cervical discectomy and fusion, minimally invasive lumbar discectomy, or minimally invasive transforaminal lumbar interbody fusion procedures between 2013 and 2014 were prospectively identified. The accuracy of self-reporting preoperative narcotic consumption was determined utilizing the Illinois Prescription Monitoring Program. Total inpatient narcotic consumption during postoperative Days 0 and 1 was compared according to the demographics and preoperative narcotic reporting accuracy. Similarly, the proportion of patients who continued to be dependent on narcotic medications at each postoperative visit was compared according to the demographics and preoperative narcotic reporting accuracy.

RESULTS

A total of 195 patients met the inclusion criteria. Of these, 25% did not use narcotics preoperatively, while 47% and 28% did do so with accurate and inaccurate reporting, respectively. Patients who used narcotics preoperatively were more likely to demonstrate elevated inpatient narcotic consumption (adjusted RR 5.3; 95% CI 1.4–20.1; p = 0.013). However, such patients were no more or less likely to be dependent on narcotic medications at the first (p = 0.618) or second (p = 0.798) postoperative visit. Among patients who used narcotics preoperatively, no differences were demonstrated in terms of inpatient narcotic consumption (p = 0.182) or narcotic dependence following the first (p = 0.982) or second (p = 0.866) postoperative visit according to the self-reported accuracy of preoperative narcotic utilization. The only preoperative factors that were independently associated with elevated inpatient narcotic consumption were workers’ compensation status and procedure type. The only preoperative factors that were independently associated with narcotic dependence at the first postoperative visit were female sex, workers’ compensation status, and procedure type. The only preoperative factor that was independently associated with narcotic dependence at the second postoperative visit was procedure type.

CONCLUSIONS

The findings suggest that determining the actual preoperative narcotic utilization in patients who undergo spine surgery may help optimize postoperative pain management. Approximately 75% of patients used narcotics preoperatively. Patients who used narcotics preoperatively demonstrated significantly higher inpatient narcotic consumption, but this difference did not persist following discharge. Finally, postoperative narcotic consumption (inpatient and following discharge) was independent of the self-reported accuracy of preoperative narcotic utilization. Taken together, these findings suggest that corroboration between the patient’s self-reported preoperative narcotic utilization and other sources of information (e.g., family members and narcotic registries) may be clinically valuable with respect to minimizing narcotic requirements, thereby potentially improving the management of postoperative pain.

Individual differences in acute pain-induced endogenous analgesia predict time to resolution of postoperative pain in the rat

BACKGROUND

Chronic postsurgical pain, a significant public health problem, occurs in 10 to 50% of patients undergoing major surgery. Acute pain induces endogenous analgesia termed conditioned pain modulation (CPM), and the strength of CPM preoperatively predicts the likelihood of chronic postsurgical pain. The relation between CPM and recovery from surgery has not been examined in preclinical models.

METHODS

CPM was assessed in individual rats and correlated with each animal's time course of recovery of hypersensitivity after partial spinal nerve ligation. The role of descending noradrenergic pathways in the spinal cord to mechanisms of CPM and recovery was tested using idazoxan to block noradrenergic receptors or antidopamine β-hydroxylase-conjugated saporin to ablate these pathways. Behavioral hypersensitivity, static weight bearing, and spinal glial activation were measured after partial spinal nerve ligation.

RESULTS

The strength of CPM varied over two-fold between individuals and was directly correlated with the slope of recovery from hypersensitivity after surgery (P < 0.0001; r = 0.660). CPM induced the release of norepinephrine in the spinal cord and was partially blocked by intrathecal idazoxan or dopamine β-hydroxylase-saporin. Dopamine β-hydroxylase-saporin also slowed recovery and enhanced spinal glial activation after partial spinal nerve ligation surgery. Ongoing activation of these pathways was critical to sustained recovery because intrathecal dopamine β-hydroxylase-saporin given 7 weeks after recovery reinstituted hypersensitivity, while having no effect in animals without previous surgery.

CONCLUSION

Collectively, these studies provide a clear back-translation from clinical observations of CPM and chronic postsurgical pain and suggest that the ability to engage ongoing descending endogenous noradrenergic signaling may be critical in determining time course of recovery from hypersensitivity after surgery.

Approach to pain management in chronic opioid users undergoing orthopaedic surgery

Opioids are commonly used for the management of pain in patients with musculoskeletal disorders; however, national attention has highlighted the potential adverse effects of the use of opioid analgesia in this and other nonmalignant pain settings. Chronic opioid users undergoing orthopaedic surgery represent a particularly challenging patient population in regard to their perioperative pain control and outcomes. Preoperative evaluation provides an opportunity to estimate a patient's preoperative opioid intake, discuss pain-related fears, and identify potential psychiatric comorbidities. Patients using high levels of opioids may also require referral to an addiction specialist. Various regional blockade and pharmaceutical options are available to help control perioperative pain, and a multimodal pain management approach may be of particular benefit in chronic opioid users undergoing orthopaedic surgery.

Opioids enhance CXCL1 expression and function after incision in mice

Chronic opioid consumption increases postoperative pain. Epigenetic changes related to chronic opioid use and surgical incision may be partially responsible for this enhancement. The CXCL1/CXCR2 signaling pathway, implicated in several pain models, is known to be epigenetically regulated via histone acetylation. The current study was designed to investigate the role of CXCL1/CXCR2 signaling in opioid-enhanced incisional sensitization and to elucidate the possible epigenetic mechanism underlying CXCL1/CXCR2 pathway-mediated regulation of nociceptive sensitization in mice. Chronic morphine treatment generated mechanical and thermal nociceptive sensitization and also significantly exacerbated incision-induced mechanical allodynia. Peripheral but not central messenger RNA levels of CXCL1 and CXCR2 were increased after incision. The source of peripheral CXCL1 appeared to be wound area neutrophils. Histone H3 subunit acetylated at the lysine 9 position (AcH3K9) was increased in infiltrating dermal neutrophils after incision and was further increased in mice with chronic morphine treatment. The association of AcH3K9 with the promoter region of CXCL1 was enhanced in mice after chronic morphine treatment. The increase in CXCL1 near wounds caused by chronic morphine pretreatment was mimicked by pharmacologic inhibition of histone deacetylation. Finally, local injection of CXCL1 induced mechanical sensitivity in naive mice, whereas blocking CXCR2 reversed mechanical hypersensitivity after hind paw incision.

PERSPECTIVE

Peripheral CXCL1/CXCR2 signaling helps to control nociceptive sensitization after incision, and epigenetic regulation of CXCL1 expression explains in part opioid-enhanced incisional allodynia in mice. These results suggest that targeting CXCL1/CXCR2 signaling may be useful in treating nociceptive sensitization, particularly for postoperative pain in chronic opioid-consuming patients.

Differential suppression of intracranial self-stimulation, food-maintained operant responding, and open field activity by paw incision and spinal nerve ligation in rats

BACKGROUND

Detection of ongoing spontaneous pain behaviors in laboratory animals remains a research challenge. Most preclinical pain studies measure elicited behavioral responses to an external noxious stimulus; however, ongoing spontaneous pain in humans and animals may be unrelated to hypersensitivity, and likely diminishes many behaviors, particularly motivated behaviors, that we hypothesize will decrease after induction of acute and chronic pain.

METHODS

In this study, 201 male rats were subjected to paw incision (INC), L5/L6 spinal nerve ligation (SNL), or INC in SNL rats, and the effects on paw withdrawal threshold (PWT) were assessed. For comparison, the behavioral-decreasing effects on nonevoked measures, including lever pressing for rewarding electrical stimulation of the ventral tegmental area intracranial self-stimulation (VTA ICSS) or food reinforcement (FR), and open field activity (OFA), were also assessed in these same rats.

RESULTS

INC decreased PWT for 4 days, decreased VTA ICSS for 2 days, and FR for 1 day but did not alter OFA. SNL decreased PWT similarly to INC but did not decrease VTA ICSS or FR; SNL did however decrease OFA. INC in SNL rats reduced PWT, VTA ICSS, and FR similarly to INC alone and did not decrease OFA compared with SNL alone.

CONCLUSIONS

The acute effects of INC on decreasing lever pressing for VTA ICSS and FR (1-2 days after incision) correspond to the timeframe in which ongoing spontaneous pain is expected to occur after INC. Therefore, these decreases are likely mediated by ongoing spontaneous pain, which may be unrelated to mechanical hypersensitivity that persists for up to 4 days after INC. PWT is decreased similarly by SNL, yet operant behavior (lever pressing for VTA ICSS and FR) was not decreased by SNL. SNL, but not INC, decreased rearing behavior but not total distance traveled during OFA. This further indicates that the presence and the extent of hypersensitivity are not predictive of many behavioral changes in rats thought to be mediated by the presence of ongoing pain. Surprisingly, the behavioral effects of INC are not exacerbated in SNL rats. These data support the growing belief that acute pain models produce short-lived spontaneous pain behaviors that are often less pronounced or absent in neuropathic pain models, and highlight the need for assessment of both evoked and nonevoked pain behaviors in developing future therapies for acute and chronic pain.

Total pancreatectomy and islet autotransplantation in chronic pancreatitis: recommendations from PancreasFest

DESCRIPTION

Total pancreatectomy with islet autotransplantation (TPIAT) is a surgical procedure used to treat severe complications of chronic pancreatitis or very high risk of pancreatic cancer while reducing the risk of severe diabetes mellitus. However, clear guidance on indications, contraindications, evaluation, timing, and follow-up are lacking.

METHODS

A working group reviewed the medical, psychological, and surgical options and supporting literature related to TPIAT for a consensus meeting during PancreasFest.

RESULTS

Five major areas requiring clinical evaluation and management were addressed: These included: 1) indications for TPIAT; 2) contraindications for TPIAT; 3) optimal timing of the procedure; 4) need for a multi-disciplinary team and the roles of the members; 5) life-long management issues following TPIAP including diabetes monitoring and nutrition evaluation.

CONCLUSIONS

TPIAT is an effective method of managing the disabling complications of chronic pancreatitis and risk of pancreatic cancer in very high risk patients. Careful evaluation and long-term management of candidate patients by qualified multidisciplinary teams is required. Multiple recommendations for further research were also identified.

Persistent post-surgical pain and experimental pain sensitivity in the Tromsø study: comorbid pain matters

In a large survey incorporating medical examination (N=12,981), information on chronic pain and surgery was collected, and sensitivity to different pain modalities was tested. Tolerance to the cold pressor test was analysed with survival statistics for 10,486 individuals, perceived cold pressor pain intensity was calculated for 10,367 individuals, heat pain threshold was assessed for 4,054 individuals, and pressure pain sensitivity for 4,689 individuals. Persistent post-surgical pain, defined by self-report, was associated with lower cold pressor tolerance (sex-adjusted hazard ratio=1.34, 95% confidence interval=1.08-1.66), but not when adjusting for other chronic pain. Other experimental pain modalities did not differentiate between individuals with or without post-surgical pain. Of the individuals with chronic pain (N=3352), 6.2% indicated surgery as a cause, although only 0.5% indicated surgery as the only cause. The associations found between persistent post-surgical pain and cold pressor tolerance is largely explained by the co-existence of chronic pain from other causes. We conclude that most cases of persistent post-surgical pain are coexistent with other chronic pain, and that, in an unselected post-surgical population, persistent post-surgical pain is not significantly associated with pain sensitivity when controlling for comorbid pain from other causes. A low prevalence of self-reported persistent pain from surgery attenuates statistically significant associations. We hypothesize that general chronic pain is associated with central changes in pain processing as expressed by reduced tolerance for the cold pressor test.

[Postoperative pain trajectories to identify risk of chronic postsurgical pain in living donors for liver transplantation]

OBJECTIVES

To assess pain trajectories in predicting risk of chronic postoperative pain (CPP) after liver resection for living donor transplantation.

STUDY DESIGN

Retrospective analysis of patients undergoing liver resection for living donor transplantation during 3years.

PATIENTS AND METHODS

After recording perioperative data, patients presenting CPP at 3months were separated from patients without postsurgical pain problem in order to build a pain trajectory for liver donor patients without CPP. Postoperative course of liver donors with CPP was then compared to that standard pain trajectory.

RESULTS

Sixty-five patients (30 females, 35 males) were included. Epidural analgesia was used in 66%; others received autocontrolled analgesia by morphine. Severe acute pain was expressed by 11% and 37% at rest and movement respectively on the first day. Chronic pain involved six patients without any link with gender or type of analgesia. Analysis of pain trajectories shown that these patients presented either higher initial pain at day 1 or positive slopes with worsening of pain.

CONCLUSION

Acute postoperative pain is a risk factor of developing CPP. Identification of those people by pain trajectories can be useful to treat them early.

The transition from acute to chronic pain: might intensive care unit patients be at risk?

Pain remains a significant problem for patients hospitalized in intensive care units (ICUs). As research has shown, for some of these patients pain might even persist after discharge and become chronic. Exposure to intense pain and stress during medical and nursing procedures could be a risk factor that contributes to the transition from acute to chronic pain, which is a major disruption of the pain neurological system. New evidence suggests that physiological alterations contributing to chronic pain states take place both in the peripheral and central nervous systems. The purpose of this paper is to: 1) review cutting-edge theories regarding pain and mechanisms that underlie the transition from acute to chronic pain, such as increases in membrane excitability of peripheral and central nerve fibers, synaptic plasticity, and loss of the function of descending inhibitory pain fibers; 2) provide information on the association between the immune system and pain and its crucial contribution to development of chronic pain syndromes, and 3) discuss mechanisms at brain levels in the nervous system and their contribution to affective (i.e., emotional) states associated with chronic pain conditions. Finally, we will offer suggestions for ICU clinical interventions to attempt to prevent the transition from acute to chronic pain.

Postoperative pain trajectories in cardiac surgery patients

Poorly controlled postoperative pain is a longstanding and costly problem in medicine. The purposes of this study were to characterize the acute pain trajectories over the first four postoperative days in 83 cardiac surgery patients with a mixed effects model of linear growth to determine whether statistically significant individual differences exist in these pain trajectories, and to compare the quality of measurement by trajectory with conventional pain measurement practices. The data conformed to a linear model that provided slope (rate of change) as a basis for comparing patients. Slopes varied significantly across patients, indicating that the direction and rate of change in pain during the first four days of recovery from surgery differed systematically across individuals. Of the 83 patients, 24 had decreasing pain after surgery, 24 had increasing pain, and the remaining 35 had approximately constant levels of pain over the four postoperative days.