Volatility and change in chronic pain severity predict outcomes of treatment for prescription opioid addiction

Electroacupuncture produces analgesic effects via cannabinoid CB1 receptor-mediated GABAergic neuronal inhibition in the rostral ventromedial medulla

OBJECTIVE

Electroacupuncture (EA) is commonly used for pain control in clinical practice, yet the precise mechanisms underlying its action are not fully understood. The rostral ventromedial medulla (RVM) plays a crucial role in the modulation of pain. GABAergic neurons in the RVM (GABARVM neurons) facilitate nociceptive transmission by inhibiting off-cells activity. This research examined the role of GABARVM neurons in the analgesic effects of EA.

METHODS

Nociceptive behavior was evaluated using inflammatory pain models induced by complete Freund's adjuvant (CFA) and neuropathic pain models induced by chronic constrictive injury (CCI). Also, in situ hybridization, chemogenetics, in vivo mouse calcium imaging, and in vivo electrophysiological recordings were used to determine neuronal activity and neural circuitry.

RESULTS

EA at the "Zusanli" (ST36) on the affected side produced a significant analgesic effect in both CFA and CCI models. CFA treatment and CCI elevated the calcium activity of GABARVM neurons. Also, EA reduced the calcium activity, neuronal firing rates, and c-Fos expression of GABARVM neurons in both pain models. Chemogenetic inhibition of GABARVM neurons increased nociceptive thresholds. Chemogenetic activation of GABARVM neurons caused increased pain sensitivity in control mice and negated the analgesic effects of EA in both pain models. Moreover, reducing cannabinoid CB1 receptors on GABARVM neurons counteracted the analgesic effects of EA in CFA and CCI-induced pain models.

CONCLUSIONS

The study indicates that the analgesic effect of EA in inflammatory and neuropathic pain is facilitated by CB1 receptor-mediated inhibition of GABARVM neurons.

Pain medication tapering in chronic pain patients: a concept analysis

STUDY OBJECTIVE

When risks and side effects of pain medication use outweigh its benefits, pain medication tapering (PMT) should be considered. PMT gained prominence in the treatment plan for patients with chronic pain (CP) and consist of heterogeneous components. This study aims to clarify the concept of PMT by conceptualizing essential components for use in CP patients.

DESIGN

Concept analysis based on the eight-step method of Walker and Avant.

DATA SOURCES

A comprehensive literature search up to July 2023 was performed in six databases: MEDLINE (via PubMed), Web of Science, Embase, Scopus, PsychINFO and the Cochrane database.

PATIENTS

CP patients on long-term pain medication therapy to whom PMT is beneficial.

INTERVENTIONS

Attributes, illustrative cases, antecedents, consequences and empirical referents were developed. The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were used for transparency and reproducibility of the search, and to increase readability and clarity.

MAIN RESULTS

Out of 4,162 articles, 110 articles were included. Six attributes were identified: medication use and decrease, support, patient preparation/education, personalization, controlling and monitoring throughout and following tapering, and alternative treatments for pain relief. Three cases were developed, illustrating PMT programs containing all, some or none of the attributes. Antecedents such as suitability for tapering, convinced patient, experienced multidisciplinary team and well-established patient-physician relationship were identified, and consequences were described according to the International Classification of Functioning, Disability and Health, with results predominantly found in the body functions and structures category.

CONCLUSION

Conceptualization of PMT for patients with CNCP creates a common ground for improving current knowledge about PMT programs and can serve as a starting point for development of future research into PMT interventions.

Pain severity contributes to worse outcomes in opioid use disorder recovery than pain status

BACKGROUND

Opioid use disorder (OUD) continues to pose a significant challenge to public health in the United States. Chronic pain and OUD are highly comorbid conditions, yet few studies have examined the relative associations of pain status and severity toward multidimensional OUD recovery outcomes (e.g., psychopathology and withdrawal).

METHODS

Participants (N = 214) were from the RECOVER-LT study, conducted 4.2-years after completion of a clinical trial program assessing extended-release buprenorphine. Group differences by pain status (i.e., chronic, acute, or no pain) were evaluated in this cross-sectional data set using analysis of variance and Fisher's exact test. Linear regression was utilized to understand the associations between average pain severity and recovery outcomes. Model selection was performed to examine the relative importance of pain status and average pain severity to recovery outcomes.

RESULTS

A majority of the sample endorsed chronic pain (73.8 %). The multivariate regression analysis with model selection found that higher average pain severity (p < .001), but not pain status, was significantly associated with the multidimensional recovery outcomes greater total number of DSM-5 OUD symptoms, higher opioid withdrawal score, reduced physical quality of life, higher depressive symptoms, negative affect, and greater psychological distress. Pain status and average pain severity were not associated with past 7- or 30-day opioid use (p > 0.001).

CONCLUSIONS

These findings highlight pain severity, but not pain status, as a key dimension of OUD recovery. This suggests a need for integration of OUD treatment and pain management, particularly for individuals experiencing elevated pain severity regardless of pain status.

Stepped Care for Patients to Optimize Whole Recovery (SC-POWR): An Effectiveness Trial Evaluating a Stepped Care Model for Individuals With Opioid Use Disorder and Chronic Pain

Many patients who receive treatment for opioid use disorder (OUD) report experiencing chronic pain (CP), which is associated with high levels of ongoing nonmedical opioid use and low retention in OUD treatment. In pilot studies of patients with OUD receiving buprenorphine or methadone who had CP, cognitive behavioral therapy (CBT) attenuated nonmedical opioid use compared with treatment-as-usual (TAU), but patients in both treatment arms exhibited similar pain improvements. Adding exercise and stress reduction to this model may augment pain-related outcomes. With funding from National Institutes of Health, we plan to conduct a randomized clinical trial of 316 patients with OUD and CP to test the effectiveness of TAU compared with Stepped Care for Patients to Optimize Whole Recovery (SC-POWR) to reduce nonmedical opioid use and pain (primary outcomes) (Aim 1) and decrease pain intensity and interference, alcohol use, anxiety, depression and stress, and improve sleep (secondary outcomes) (Aim 2). Eligible participants will be randomized to receive TAU (buprenorphine or methadone and at least once a month individual or group counseling) or SC-POWR (ie, TAU and up to 12 CBT sessions) for 24 weeks. Based on prespecified nonresponse criteria, SC-POWR may be stepped up at week 6 to receive onsite weekly group sessions of exercise (Wii Fit, Tai Chi) and "stepped up" again at week 15 to receive weekly group sessions of stress reduction (relaxation training, auricular acupuncture). They will be followed for another 24 weeks to evaluate durability of treatment response for illicit opioid use, alcohol use, pain, anxiety, depression, stress, sleep, and retention in medications for OUD (Aim 3).

Efficacy of Integrating the Management of Pain and Addiction via Collaborative Treatment (IMPACT) in Individuals With Chronic Pain and Opioid Use Disorder: Protocol for a Randomized Clinical Trial of a Digital Cognitive Behavioral Treatment

BACKGROUND

Chronic pain is common among individuals with opioid use disorder (OUD) who are maintained on medications for OUD (MOUD; eg, buprenorphine or methadone). Chronic pain is associated with worse retention and higher levels of substance use. Treatment of individuals with chronic pain receiving MOUD can be challenging due to their increased clinical complexity. Given the acute and growing nature of the opioid crisis, MOUD is increasingly offered in a wide range of settings, where high-quality, clinician-delivered, empirically validated behavioral treatment for chronic pain may not be available. Therefore, digital treatments that support patient self-management of chronic pain and OUD have the potential for wider implementation to fill this gap.

OBJECTIVE

This study aims to evaluate the efficacy of Integrating the Management of Pain and Addiction via Collaborative Treatment (IMPACT), an interactive digital treatment program with asynchronous coach feedback, compared to treatment as usual (TAU) in individuals with chronic pain and OUD receiving MOUD.

METHODS

Adult participants (n=160) receiving MOUD and reporting bothersome or high-impact chronic pain will be recruited from outpatient opioid treatment programs in Connecticut (United States) and randomized 1:1 to either IMPACT+TAU or TAU only. Participants randomized to IMPACT+TAU will complete an interactive digital treatment that includes 9 modules promoting training in pain and addiction coping skills and a progressive walking program. The program is augmented with a weekly personalized voice message from a trained coach based on daily participant-reported pain intensity and interference, craving to use opioids, sleep quality, daily steps, pain self-efficacy, MOUD adherence, and engagement with IMPACT collected through digital surveys. Outcomes will be assessed at 3, 6, and 9 months post randomization. The primary outcome is MOUD retention at 3 months post randomization (ie, post treatment). Secondary outcomes include pain interference, physical functioning, MOUD adherence, substance use, craving, pain intensity, sleep disturbance, pain catastrophizing, and pain self-efficacy. Semistructured qualitative interviews with study participants (n=34) randomized to IMPACT (completers and noncompleters) will be conducted to evaluate the usability and quality of the program and its outcomes.

RESULTS

The study has received institutional review board approval and began recruitment at 1 site in July 2022. Recruitment at a second site started in January 2023, with a third and final site anticipated to begin recruitment in January 2024. Data collection is expected to continue through June 2025.

CONCLUSIONS

Establishing efficacy for a digital treatment for addiction and chronic pain that can be integrated into MOUD clinics will provide options for individuals with OUD, which reduce barriers to behavioral treatment. Participant feedback on the intervention will inform updates or modifications to improve engagement and efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05204576; https://clinicaltrials.gov/ct2/show/NCT05204576.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/54342.

Endogenous opioid systems alterations in pain and opioid use disorder

Decades of research advances have established a central role for endogenous opioid systems in regulating reward processing, mood, motivation, learning and memory, gastrointestinal function, and pain relief. Endogenous opioid systems are present ubiquitously throughout the central and peripheral nervous system. They are composed of four families, namely the μ (MOPR), κ (KOPR), δ (DOPR), and nociceptin/orphanin FQ (NOPR) opioid receptors systems. These receptors signal through the action of their endogenous opioid peptides β-endorphins, dynorphins, enkephalins, and nociceptins, respectfully, to maintain homeostasis under normal physiological states. Due to their prominent role in pain regulation, exogenous opioids-primarily targeting the MOPR, have been historically used in medicine as analgesics, but their ability to produce euphoric effects also present high risks for abuse. The ability of pain and opioid use to perturb endogenous opioid system function, particularly within the central nervous system, may increase the likelihood of developing opioid use disorder (OUD). Today, the opioid crisis represents a major social, economic, and public health concern. In this review, we summarize the current state of the literature on the function, expression, pharmacology, and regulation of endogenous opioid systems in pain. Additionally, we discuss the adaptations in the endogenous opioid systems upon use of exogenous opioids which contribute to the development of OUD. Finally, we describe the intricate relationship between pain, endogenous opioid systems, and the proclivity for opioid misuse, as well as potential advances in generating safer and more efficient pain therapies.

Association of chronic non-cancer pain status and buprenorphine treatment retention among individuals with opioid use disorder: Results from electronic health record data

Background

Although chronic non-cancer pain (CNCP) is common among individuals with opioid use disorder (OUD), its impact on buprenorphine treatment retention is unclear. The goal of this study was to use electronic health record (EHR) data to examine the association of CNCP status and 6-month buprenorphine retention among patients with OUD.

Methods

We analyzed EHR data of patients with OUD who received buprenorphine treatment in an academic healthcare system between 2010 and 2020 (N = 676). We used Kaplan-Meier curves and Cox proportional hazards regression to estimate risk of buprenorphine treatment discontinuation (≥90 days between subsequent prescriptions). We used Poisson regression to estimate the association of CNCP and the number of buprenorphine prescriptions over 6 months.

Results

Compared to those without CNCP, a higher proportion of patients with CNCP were of older age and had comorbid diagnoses for psychiatric and substance use disorders. There were no differences in the probability of buprenorphine treatment continuation over 6 months by CNCP status (p = 0.15). In the adjusted cox regression model, the presence of CNCP was not associated with time to buprenorphine treatment discontinuation (HR = 0.90, p = 0.28). CNCP status was associated with a higher number of prescriptions over 6 months (IRR = 1.20, p < 0.01).

Conclusions

These findings suggest that the presence of CNCP alone cannot be reliably associated with buprenorphine retention in patients with OUD. Nonetheless, providers should be aware of the association between CNCP and greater psychiatric comorbidity among patients with OUD when developing treatment plans. Research on the influence of additional characteristics of CNCP on treatment retention is needed.

Efficacy of interventions to reduce long term opioid treatment for chronic non-cancer pain: systematic review and meta-analysis

OBJECTIVE

To review interventions to reduce long term opioid treatment in people with chronic non-cancer pain, considering efficacy on dose reduction and discontinuation, pain, function, quality of life, withdrawal symptoms, substance use, and adverse events.

DESIGN

Systematic review and meta-analysis of randomised controlled trials and non-randomised studies of interventions.

DATA SOURCES

Medline, Embase, PsycINFO, CINAHL, and the Cochrane Library searched from inception to July 2021. Reference lists and previous reviews were also searched and experts were contacted.

ELIGIBILITY CRITERIA FOR STUDY SELECTION

Original research in English. Case reports and cross sectional studies were excluded.

DATA EXTRACTION AND SYNTHESIS

Two authors independently selected studies, extracted data, and used the Cochrane risk-of-bias tools for randomised and non-randomised studies (RoB 2 and ROBINS-I). Authors grouped interventions into five categories (pain self-management, complementary and alternative medicine, pharmacological and biomedical devices and interventions, opioid replacement treatment, and deprescription methods), estimated pooled effects using random effects meta-analytical models, and appraised the certainty of evidence using GRADE (grading of recommendations, assessment, development, and evaluation).

RESULTS

Of 166 studies meeting inclusion criteria, 130 (78%) were considered at critical risk of bias and were excluded from the evidence synthesis. Of the 36 included studies, few had comparable treatment arms and sample sizes were generally small. Consequently, the certainty of the evidence was low or very low for more than 90% (41/44) of GRADE outcomes, including for all non-opioid patient outcomes. Despite these limitations, evidence of moderate certainty indicated that interventions to support prescribers' adherence to guidelines increased the likelihood of patients discontinuing opioid treatment (adjusted odds ratio 1.5, 95% confidence interval 1.0 to 2.1), and that these prescriber interventions as well as pain self-management programmes reduced opioid dose more than controls (intervention v control, mean difference -6.8 mg (standard error 1.6) daily oral morphine equivalent, P<0.001; pain programme v control, -14.31 mg daily oral morphine equivalent, 95% confidence interval -21.57 to -7.05).

CONCLUSIONS

Evidence on the reduction of long term opioid treatment for chronic pain continues to be constrained by poor study methodology. Of particular concern is the lack of evidence relating to possible harms. Agreed standards for designing and reporting studies on the reduction of opioid treatment are urgently needed.

REVIEW REGISTRATION

PROSPERO CRD42020140943.

Evaluation of Buprenorphine Rotation in Patients Receiving Long-term Opioids for Chronic Pain: A Systematic Review

IMPORTANCE

Individuals with chronic pain who use long-term opioid therapy (LTOT) are at risk of opioid use disorder and other harmful outcomes. Rotation to buprenorphine may be considered, but the outcomes of such rotation in this population have not been systematically reviewed.

OBJECTIVE

To synthesize the evidence on rotation to buprenorphine from full μ-opioid receptor agonists among individuals with chronic pain who were receiving LTOT, including the outcomes of precipitated opioid withdrawal, pain intensity, pain interference, treatment success, adverse events or adverse effects, mental health condition, and health care use.

EVIDENCE REVIEW

PubMed, CINAHL, Embase, and PsycInfo were searched from inception through November 3, 2020, for peer-reviewed original English-language research that reported the prespecified outcomes of rotation from prescribed long-term opioids to buprenorphine among individuals with chronic pain. Two independent reviewers extracted data as well as assessed risk of bias and study quality according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Quality of evidence was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

FINDINGS

A total of 22 studies were analyzed, of which 5 (22.7%) were randomized clinical trials, 7 (31.8%) were case-control or cohort studies, and 10 (45.5%) were uncontrolled pre-post studies, which involved 1616 unique participants (675 female [41.8%] and 941 male [58.2%] individuals). Six of the 22 studies (27.3%) were primary or secondary analyses of a large randomized clinical trial. Participants had diverse pain and opioid use histories. Rationale for buprenorphine rotation included inadequate analgesia, intolerable adverse effects, risky opioid regimens (eg, high dose and/or sedative coprescriptions), and aberrant opioid use. Most protocols were adapted from protocols for initiating treatment in patients with opioid use disorder and used buccal or sublingual buprenorphine. Very low-quality evidence suggested that buprenorphine rotation was associated with maintained or improved analgesia, with a low risk of precipitating opioid withdrawal. Steady-dose buprenorphine was better tolerated than tapered-dose buprenorphine. Adverse effects were manageable, and severe adverse events were rare. Only 2 studies evaluated mental health outcomes, but none evaluated health care use. Limitations included a high risk of bias in most studies.

CONCLUSIONS AND RELEVANCE

In this systematic review, buprenorphine was associated with reduced chronic pain intensity without precipitating opioid withdrawal in individuals with chronic pain who were receiving LTOT. Future studies are necessary to ascertain the ideal starting dose, formulation, and administration frequency of buprenorphine as well as the best approach to buprenorphine rotation.

Opioid Tapering/Detoxification Protocols, A Compendium: Narrative Review

OBJECTIVES

The opioid epidemic has put pressure on clinicians to taper their chronic pain patients (CPPs) from opioids. This has resulted in rapid or forced tapers and opioid discontinuation. Partially responsible is lack of information on how to taper (tapering protocols).The objectives of this narrative review were then the following: compile all the published opioid tapering/detoxification protocols from the pain/drug rehabilitation/psychiatric literature whether for inpatient or outpatient use; organize these into general types; compare the types for advantages/disadvantages for use by a clinician in an outpatient setting; and answer some commonly asked questions relating to opioid tapering.

METHODS

Relevant references were identified by a search strategy utilizing the terms tapering, tapering protocols, detoxification, detoxification protocols, withdrawal, dependence, addiction, and drug rehabilitation. These were explored with the term opioids. Identified abstract were reviewed for any study relating to the objectives of this review. Those studies were then included in this review. As this is a narrative review, no quality ratings of these references were performed.

RESULTS

Of 1,922 abstracts identified by this search strategy, 301 were reviewed in detail for potential inclusion. Of these, 104 were utilized in this review. Nine types of opioid tapering protocols were identified and compared in tabular form. Twenty-two questions in reference to opioid tapering were addressed.

CONCLUSIONS

Based on this review, the protocol utilizing the opioid of current use is the simplest to use as it requires no rotation to another opioid and thereby avoids rotation errors. It also has behavior advantages.

Pain Anxiety as a Mechanism Linking Pain Severity and Opioid Misuse and Disability Among Individuals With Chronic Pain

OBJECTIVE

Chronic pain affects a significant number of individuals in the United States and is associated with several negative health-related outcomes, including possibility of opioid misuse and disability. The identification of factors associated with both opioid misuse and disability is of critical public health importance, and significant research suggests that pain severity has been shown to be associated with both. Pain-related anxiety has been uniquely associated with both opioid misuse and disability, yet little research has examined pain-related anxiety as a potential mechanism linking pain severity with opioid misuse and disability.

METHOD

Therefore, the current study examined whether pain-related anxiety explains, in part, the relationship between pain severity, opioid misuse, and disability among 396 adults with chronic pain (55.8% female, Mage 36.61, SD 11.40).

RESULTS

Cross-sectional analyses indicated that pain-related anxiety significantly mediated the relationship between pain severity, opioid misuse outcomes, and psychosocial disability, but not physical disability.

CONCLUSIONS

These results build upon the literature indicating the importance of pain-related anxiety in those with chronic pain by suggesting this construct may account, in part, for the relation of pain intensity to opioid misuse and psychosocial disability. Future research should longitudinally examine these associations.

Depression and Buprenorphine Treatment in Patients with Non-cancer Pain and Prescription Opioid Dependence without Comorbid Substance Use Disorders

BACKGROUND

Depression occurs in 40% of patients with prescription opioid dependence (POD). Existing studies of the association between depression and buprenorphine (BUP) treatment for POD are inconsistent and often include patients with comorbid substance use disorders (SUD). We estimated the association between depression and BUP use in patients with pain and POD and free of comorbid SUD.

METHODS

Optum® de-identified Electronic Health Record dataset from 2010 to 2018 was used to identify 5,529 patients with chronic pain, with and without depression, receiving prescription opioids and free of substance use disorder diagnoses for one year before POD diagnoses. Unadjusted and adjusted Cox proportional hazard models and negative binomial regression models were computed to estimate the association between depression and time to BUP start, number of BUP prescriptions in the year after BUP start and time to >30 day BUP gap.

RESULTS

Patients' mean age was 52.4 (SD±15.3) years, 62% were female and 84% were white and 4.9% (n=270) started BUP. Depression was not associated with BUP initiation.. Among BUP starters, depression vs. no depression, was significantly associated with receiving 29% fewer BUP prescriptions (RR=0.71; 95%CI: 0.51-0.98) and an increased risk for > 30 day gap (HR=1.76; 95%CI:1.01-3.09).

LIMITATIONS

Missing data prevented measuring BUP dose.

CONCLUSIONS

Depression is likely associated with earlier BUP treatment dropout. Depression related medication non-adherence or possible worsening of depression following BUP taper could explain results. Research is needed to determine if depression severity is associated with BUP dose trajectories and multi-year BUP retention..

Kappa Opioid Signaling at the Crossroads of Chronic Pain and Opioid Addiction

Pain is complex and is a unique experience for individuals in that no two people will have exactly the same physiological and emotional response to the same noxious stimulus or injury. Pain is composed of two essential processes: a sensory component that allows for discrimination of the intensity and location of a painful stimulus and an emotional component that underlies the affective, motivational, unpleasant, and aversive response to a painful stimulus. Kappa opioid receptor (KOR) activation in the periphery and throughout the neuroaxis modulates both of these components of the pain experience. In this chapter we focus on recent findings that KORs contribute to the emotional, aversive nature of chronic pain, including how expression in the limbic circuitry contributes to anhedonic states and components of opioid misuse disorder. While the primary focus is on preclinical pain models, we also highlight clinical or human research where there is strong evidence for KOR involvement in negative affective states associated with chronic pain and opioid misuse.

Characterization of Bodily Pain and Use of Both Prescription and Non-Prescription Opioids in Tenants of Precarious Housing

opioid use, which includes both prescribed and non-prescribed drugs, is relatively common amongst marginalized populations. Past research has shown that among those who use non-prescribed or diverted opioids recreationally, many were first exposed to the drug as prescribed pain medication. Objective: to better understand the relationship between pain and opioid use in tenants of precarious housing. Methods: in the present study, 440 individuals from a cohort living in homeless or precariously housed conditions in a neighborhood with high rates of poverty and drug use were interviewed for their bodily pain and opioid use. We examined the relationship between bodily pain levels, assessed using the Maudsley Addiction Profile questionnaire, and prescribed, non-prescribed and combined self-reported opioid use in the prior 28 days assessed using the Timeline Followback and Doctor-Prescribed Medication Timeline Followback questionnaires. Results: Analysis of the results indicated that sex (female), age (younger) and early exposure to opioids (≤ age 18) predicted current opioid use, but there was no association between current bodily pain levels and opioid use. Conclusions: these unexpected findings indicate the complex nature of the relationship between pain and opioid use in this population.

Greater Pain Severity is Associated with Inability to Access Addiction Treatment Among a Cohort of People Who Use Drugs

Aim

Given that co-occurring pain is prevalent among people who use drugs (PWUD), we sought to explore the effect of pain severity on accessing addiction treatment.

Methods

Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada from June 2014 to May 2016. Multivariable generalized linear mixed-effects multiple regression (GLMM) analyses were used to investigate the association between average pain severity and self-reported inability to access addiction treatment.

Results

Among 1348 PWUD, 136 (10.1%) reported being unable to access addiction treatment at least once over the study period. Individuals who reported being unable to access addiction treatment had a significantly higher median average pain severity score (median=5, IQR=0-7) compared to individuals reporting no inability to access addiction treatment (median=3, IQR=0-6, p=0.038). Greater pain severity was independently associated with higher odds of reporting inability to access addiction treatment (AOR: 1.75, 95%CI: 1.08-2.82 for mild-moderate vs no pain; AOR: 1.98, 95%CI: 1.27-3.09 for moderate-severe vs no pain).

Conclusion

PWUD with greater pain severity may be at higher risk of being unable to access addiction treatment, or vice versa. While further research is needed to confirm causal associations, these data suggest that there may be underlying pathways or mechanisms through which pain may be associated with access to addiction treatment for PWUD.

Correlates of Treatment Retention and Opioid Misuse Among Postpartum Women in Methadone Treatment

OBJECTIVES

The postpartum period is a particularly challenging time for women in methadone treatment. Unfortunately, this is also the time when women are vulnerable to treatment discontinuation and opioid misuse. The purpose of the present exploratory study was to examine demographic, treatment, and delivery factors that may be associated with postbirth retention in treatment and opioid misuse.

METHODS

A chart review was conducted among postpartum women (n = 81) receiving opioid agonist treatment during pregnancy.

RESULTS

Results revealed that treatment discharge and postbirth opioid misuse were common after delivery. Longer treatment duration before delivery was associated with a lower likelihood of opioid misuse in the month after delivery. Women who delivered via cesarean section and received a discharge opioid medication were also more likely to engage in opioid misuse (ie, providing an opioid-positive urine toxicology screen outside the window of detection for the discharge opioid prescription) in the month after delivery.

CONCLUSIONS

Increasing support to minimize the likelihood of treatment discontinuation or opioid misuse may be particularly important in this period, especially for this vulnerable group.

Chronic non-cancer pain among adults with substance use disorders: Prevalence, characteristics, and association with opioid overdose and healthcare utilization

BACKGROUND

Chronic non-cancer pain (CNCP) among patients with substance use disorder (SUD) poses a risk for worse treatment outcomes. Understanding the association of CNCP with SUD is important for informing the need and potential benefits of pain assessment/management among those with SUDs.

METHODS

We analyzed electronic health record data from 2013 to 2018 among adults aged ≥18 years (N = 951,533; mean age: 48.4 years; 57.4 % female) in a large academic healthcare system. Adjusted logistic regression models were conducted to estimate the association of CNCP conditions with opioid overdose, emergency department utilization, and inpatient hospitalization stratified by different SUD diagnoses and by gender.

RESULTS

Among the total sample, the prevalence of CNCP was 46.6 % and any SUD was 11.2 %. The majority of patients with a SUD had CNCP (opioid: 74.7 %; sedative: 72.3 %; cannabis: 64.3 %; alcohol: 58.7 %; tobacco: 59.5 %). The prevalence of CNCP was greater in females vs. males for most SUD diagnoses. The presence of CNCP was associated with more mental health disorders and chronic medical conditions among each SUD group. CNCP was associated with significantly decreased odds of overdose among those with opioid use disorder but increased odds of overdose and healthcare utilization among other SUDs. CNCP was positively associated with overdose in females, but not males, with alcohol or non-opioid drug use disorders.

CONCLUSIONS

The direction and magnitude of the association between CNCP and negative health indicators differed as a function of SUD type and gender, respectively. Greater awareness of potential unmet pain treatment need may have implications for improving SUD outcomes.

Interpretability and Class Imbalance in Prediction Models for Pain Volatility in Manage My Pain App Users: Analysis Using Feature Selection and Majority Voting Methods

Background

Pain volatility is an important factor in chronic pain experience and adaptation. Previously, we employed machine-learning methods to define and predict pain volatility levels from users of the Manage My Pain app. Reducing the number of features is important to help increase interpretability of such prediction models. Prediction results also need to be consolidated from multiple random subsamples to address the class imbalance issue.

Objective

This study aimed to: (1) increase the interpretability of previously developed pain volatility models by identifying the most important features that distinguish high from low volatility users; and (2) consolidate prediction results from models derived from multiple random subsamples while addressing the class imbalance issue.

Methods

A total of 132 features were extracted from the first month of app use to develop machine learning–based models for predicting pain volatility at the sixth month of app use. Three feature selection methods were applied to identify features that were significantly better predictors than other members of the large features set used for developing the prediction models: (1) Gini impurity criterion; (2) information gain criterion; and (3) Boruta. We then combined the three groups of important features determined by these algorithms to produce the final list of important features. Three machine learning methods were then employed to conduct prediction experiments using the selected important features: (1) logistic regression with ridge estimators; (2) logistic regression with least absolute shrinkage and selection operator; and (3) random forests. Multiple random under-sampling of the majority class was conducted to address class imbalance in the dataset. Subsequently, a majority voting approach was employed to consolidate prediction results from these multiple subsamples. The total number of users included in this study was 879, with a total number of 391,255 pain records.

Results

A threshold of 1.6 was established using clustering methods to differentiate between 2 classes: low volatility (n=694) and high volatility (n=185). The overall prediction accuracy is approximately 70% for both random forests and logistic regression models when using 132 features. Overall, 9 important features were identified using 3 feature selection methods. Of these 9 features, 2 are from the app use category and the other 7 are related to pain statistics. After consolidating models that were developed using random subsamples by majority voting, logistic regression models performed equally well using 132 or 9 features. Random forests performed better than logistic regression methods in predicting the high volatility class. The consolidated accuracy of random forests does not drop significantly (601/879; 68.4% vs 618/879; 70.3%) when only 9 important features are included in the prediction model.

Conclusions

We employed feature selection methods to identify important features in predicting future pain volatility. To address class imbalance, we consolidated models that were developed using multiple random subsamples by majority voting. Reducing the number of features did not result in a significant decrease in the consolidated prediction accuracy.

Perceived health, medical, and psychiatric conditions in individual and dual-use of marijuana and nonprescription opioids

OBJECTIVE

Marijuana and nonprescription opioids remain the two most commonly used illicit substances in the United States. They have commonalities, yet the use of both at the same time may have a greater impact on psychological and health outcomes. Research is needed to determine whether dual-use is associated with more negative outcomes than individual substance use.

METHOD

We used the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) Wave 1 (W1; N = 43,093), Wave 2 (W2; N = 34,653), and the more recent NESARC-III (N3; N = 36,171) to compare nonuse with use of marijuana, nonprescription opioids, or both. We examined perceived health, pain interference, pain-related medical conditions, psychiatric conditions, and suicidality.

RESULTS

Individual use and dual-use were more common in N3 than in W1. W1 dual-use and nonprescription opioid-only use predicted worse outcomes for most variables prospectively and cross-sectionally, including pain interference and poorer general health. Associations between marijuana-only use and outcomes were not as strong; however, marijuana was associated with depression and suicidal ideation.

CONCLUSION

Nonprescription opioid use is concerning with dual-use predicting poorer perceived health and pain interference with work 3 years later along with strong relationships to suicidality and psychiatric conditions. Marijuana and nonprescription opioid dual-use is a possible treatment target. Substance interventions may be enhanced by addressing alternative pain care; chronic conditions; and/or psychiatric comorbidity. Differences in outcomes between substance use and nonuse were smaller recently in N3, particularly for marijuana use only. This may be due to increased access decreasing differences between those using and not using these drugs. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Psycho-physiological response to pain among individuals with comorbid pain and opioid use disorder: Implications for patients with prolonged abstinence

Background: Individuals with comorbid opioid addiction and pain (COAP) relapse 3-5 times more often than patients with opioid use disorder (OUD) but without pain. However, psychophysiological responses to pain among a COAP population are unknown. Objectives: We hypothesized that those on Medications for Opioid Use Disorder (MOUD) with chronic pain, relative to opioid-naïve chronic pain individuals, would show greater psycho-physiological pain reactivity and slower recovery when exposed to acute pain. Methods: Four groups with chronic pain were recruited (N = 120; 60% Female): 1) MOUD-methadone; 2) MOUD-buprenorphine; 3) history of completed MOUD with prolonged opioid abstinence (PA; M_abstinence = 121 weeks; SD = 23.3); and 4) opioid-naïve. We assessed heart rate (HR), galvanic skin conductance (GSC), peripheral temperature, and frontalis electromyography (EMG) during a cold pain task. Results: MOUD subjects had delayed HR reactivity to pain compared to those not on MOUD (PA & opioid-naïve; F(3,119) = 2.87, p < .04). The PA group showed a normal HR reactivity pattern, but had higher HR compared to the opioid-naïve group. The GSC group x time analysis showed the PA group had greater baseline levels and pain reactivity than the other groups (F(3,119) = 3.84, p < .02). The opioid-naïve group had lower reactivity on peripheral temperature compared to other groups (F(3,119) = 9.69, p < .001). Conclusion: Greater psychophysiological reactivity to pain was experienced by co-morbid OUD/chronic pain subjects who had been opioid abstinent for an extended period, possibly due to the lack of a buffering effect of opioid agonists. These subjects may develop coping skills to tolerate pain distress, thereby avoiding relapse in response to pain triggers. Understanding how pain creates more intense psychophysiological responses among COAP patients may lead to better treatments.

Defining and Predicting Pain Volatility in Users of the Manage My Pain App: Analysis Using Data Mining and Machine Learning Methods

Background

Measuring and predicting pain volatility (fluctuation or variability in pain scores over time) can help improve pain management. Perceptions of pain and its consequent disabling effects are often heightened under the conditions of greater uncertainty and unpredictability associated with pain volatility.

Objective

This study aimed to use data mining and machine learning methods to (1) define a new measure of pain volatility and (2) predict future pain volatility levels from users of the pain management app, Manage My Pain, based on demographic, clinical, and app use features.

Methods

Pain volatility was defined as the mean of absolute changes between 2 consecutive self-reported pain severity scores within the observation periods. The k-means clustering algorithm was applied to users’ pain volatility scores at the first and sixth month of app use to establish a threshold discriminating low from high volatility classes. Subsequently, we extracted 130 demographic, clinical, and app usage features from the first month of app use to predict these 2 volatility classes at the sixth month of app use. Prediction models were developed using 4 methods: (1) logistic regression with ridge estimators; (2) logistic regression with Least Absolute Shrinkage and Selection Operator; (3) Random Forests; and (4) Support Vector Machines. Overall prediction accuracy and accuracy for both classes were calculated to compare the performance of the prediction models. Training and testing were conducted using 5-fold cross validation. A class imbalance issue was addressed using a random subsampling of the training dataset. Users with at least five pain records in both the predictor and outcome periods (N=782 users) are included in the analysis.

Results

k-means clustering algorithm was applied to pain volatility scores to establish a threshold of 1.6 to differentiate between low and high volatility classes. After validating the threshold using random subsamples, 2 classes were created: low volatility (n=611) and high volatility (n=171). In this class-imbalanced dataset, all 4 prediction models achieved 78.1% (611/782) to 79.0% (618/782) in overall accuracy. However, all models have a prediction accuracy of less than 18.7% (32/171) for the high volatility class. After addressing the class imbalance issue using random subsampling, results improved across all models for the high volatility class to greater than 59.6% (102/171). The prediction model based on Random Forests performs the best as it consistently achieves approximately 70% accuracy for both classes across 3 random subsamples.

Conclusions

We propose a novel method for measuring pain volatility. Cluster analysis was applied to divide users into subsets of low and high volatility classes. These classes were then predicted at the sixth month of app use with an acceptable degree of accuracy using machine learning methods based on the features extracted from demographic, clinical, and app use information from the first month.

Pain and Addiction: An Integrative Therapeutic Approach

The current opioid crisis highlights an urgent need for better paradigms for prevention and treatment of chronic pain and addiction. Although many approach this complex clinical condition with the question, "Is this pain or is this addiction?," it is more than the sum of its parts. Chronic pain among those with dependence and addiction often evolves into a complex disabling condition with pain at multiple sites, psychosocial dysfunctions, medical and psychiatric disorders, polypharmacy, and polysubstance use, all interacting with each other in complex ways (multimorbidity). The authors offer an integrative therapeutic approach to manage this complex clinical scenario.

Pain Therapy Guided by Purpose and Perspective in Light of the Opioid Epidemic

Prescription opioid misuse is an ongoing and escalating epidemic. Although these pharmacological agents are highly effective analgesics prescribed for different types of pain, opioids also induce euphoria, leading to increasing diversion and misuse. Opioid use and related mortalities have developed in spite of initial claims that OxyContin, one of the first opioids prescribed in the USA, was not addictive in the presence of pain. These claims allayed the fears of clinicians and contributed to an increase in the number of prescriptions, quantity of drugs manufactured, and the unforeseen diversion of these drugs for non-medical uses. Understanding the history of opioid drug development, the widespread marketing campaign for opioids, the immense financial incentive behind the treatment of pain, and vulnerable socioeconomic and physical demographics for opioid misuse give perspective on the current epidemic as an American-born problem that has expanded to global significance. In light of the current worldwide opioid epidemic, it is imperative that novel opioids are developed to treat pain without inducing the euphoria that fosters physical dependence and addiction. We describe insights from preclinical findings on the properties of opioid drugs that offer insights into improving abuse-deterrent formulations. One finding is that the ability of some agonists to activate one pathway over another, or agonist bias, can predict whether several novel opioid compounds bear promise in treating pain without causing reward among other off-target effects. In addition, we outline how the pharmacokinetic profile of each opioid contributes to their potential for misuse and discuss the emergence of mixed agonists as a promising pipeline of opioid-based analgesics. These insights from preclinical findings can be used to more effectively identify opioids that treat pain without causing physical dependence and subsequent opioid abuse.