Relationships Between Opioid Dosing, Pain Severity, and Disability in a Community-Based Chronic Pain Population: An Exploratory Retrospective Analysis

Prediction of sustained opioid use in children and adolescents using machine learning

BACKGROUND

Opioid misuse in the paediatric population is understudied. This study aimed to develop a machine learning classifier to differentiate between occasional and sustained opioid users among children and adolescents in outpatient settings.

METHODS

Data for 29,335 patients under 19 yr with recorded opioid purchases were collected from medical records. Machine learning methods were applied to predict sustained opioid use within 1, 2, or 3 yr after first opioid use, using sociodemographic information, medical history, and healthcare usage variables collected near the time of first prescription fulfilment. The models' performance was evaluated with classification and calibration metrics, and a decision curve analysis. An online tool was deployed for model self-exploration and visualisation.

RESULTS

The models demonstrated good performance, with a 1-yr follow-up model achieving a sensitivity of 0.772, a specificity of 0.703, and an ROC-AUC of 0.792 on an independent test set, with calibration intercept and slope of 0.00 and 1.02, respectively. Decision curve analysis revealed the clinical benefit of using the model relative to other strategies. SHAP analysis (SHapley Additive exPlanations) identified influential variables, including the number of diagnoses, medical images, laboratory tests, and type of opioid used.

CONCLUSIONS

Our model showed promising performance in predicting sustained opioid use among paediatric patients. The online risk prediction tool can facilitate compliance to such tools by clinicians. This study presents the potential of machine learning in identifying at-risk paediatric populations for sustained opioid use, potentially contributing to secondary prevention of opioid abuse.

Opioid trends and risk factors for sustained use among children and adolescents in Israel: a retrospective cohort study

ABSTRACT

Despite growing global concern over opioids, little is known about the epidemiology of opioid use in children and adolescents. This retrospective study investigated opioid use trends and identified risk factors associated with sustained opioid use among outpatient children and adolescents in Israel. Electronic health records of 110,955 children and adolescents were used to establish opioid purchase trends in outpatient settings between 2003 and 2021. Of these, data from 2012 to 2021, n = 32,956, were included in a Cox proportional hazards analysis to identify demographic, clinical, and pharmacological risk factors for sustained opioid use. An increase in opioid use was observed, with a notable rise among strong opioids, peripheral areas, and noncancer patients. Prevalence of sustained opioid users was approximately 2.5%. Risk factors with significant adjusted hazard ratios for sustained use included history of frequent doctor visits 1.82 (95% CI [1.50-2.22]) and drug purchases 1.30 (95% CI [1.07-1.58]), malignancy 1.50 (95% CI [1.07-2.09]), history of cardiovascular (1.44 (95% CI [1.04-1.98]) and pain-related conditions 1.34 (95% CI [1.14-1.58]), and different opioid substances (relative to codeine use): tramadol 2.38 (95% CI [1.73-3.27]), oxycodone 4.29 (95% CI [3.00-6.16]), and "other strong opioids" 6.05 (95% CI [3.59-10.2]). Awareness of observed increase in opioid purchases is crucial for doctors and public health practitioners. Additional monitoring and secondary prevention of children and adolescents possessing the identified risk factors should facilitate where appropriate reducing sustained opioid use when it is unnecessary.

Complex Persistent Opioid Dependence-an Opioid-induced Chronic Pain Syndrome

OPINION STATEMENT

Long-term opioid therapy (LTOT) for chronic cancer and non-cancer pain is commonly ineffective in providing its stated goal of improving function through good control of pain. Opioid tapering (slow dose reduction and/or discontinuation), the logical solution, also appears to be ineffective among many patients on LTOT as it often leads to even worse pain control and function, leaving the patients and providers managing LTOT in a clinical conundrum with little treatment choices. Complex persistent opioid dependence (CPOD) was recently offered as a heuristic to explain this clinical conundrum exemplified by the ineffectiveness of both LTOT and opioid tapering. This manuscript provides a detailed description of the neurobehavioral underpinnings of CPOD, explaining how long-term opioid use can lead to more pain even while experiencing relief with each opioid dose. CPOD is characterized by the allostatic opponent mechanisms of neuroadaptations related to the progression of opioid dependence and tolerance involving nociceptive/anti-nociceptive brain systems causing opioid-induced hyperalgesia and reward/anti-reward systems causing hyperkatefia or suffering that induces pain experience through the cognitive/emotional component of pain mechanisms. "Opioid Induced Chronic Pain syndrome" (OICP) is offered as an alternate clinical diagnostic term instead of CPOD that has several limitations as a diagnosis term including poor patient acceptance due to stigma towards addiction and clinical confounding with opioid use disorder, a related but separate clinical entity. OICP with LTOT is conceptualized as a recoverable iatrogenic problem that can be managed by pain providers. Broad guidance on management of OICP is also provided.

Opioid Taper is Associated with Improved Experimental Pain Tolerance in Patients with Chronic Pain: An Observational Study

Introduction

The degree to which opioid-induced hyperalgesia contributes to the pain experience of patients with chronic pain remains relatively undescribed. The objective of this pilot study was to determine if experimental pain responses improve in patients with chronic pain as they undergo a planned opioid taper.

Methods

This was a prospective observational study. Seven patients with chronic neuropathic pain on at least 120 mg morphine equivalents/day were enrolled. The participants were followed over the course of an individualized opioid taper to a lower dose. Measures of experimental pain sensitivity, including indicators of central pain modulation, were collected on a biweekly basis; in addition, measures of function and quality of life were collected monthly. The effect of opioid taper on pain responses and functional outcomes over time were examined using longitudinal mixed-effects regression modeling and general linear regression modeling with regularization as a function of baseline dose, end dose, and taper rate.

Results

In this small sample of patients undergoing highly individualized and variable opioid taper, the opioid taper was significantly associated with improved pain responses to the cold-pressor test, with the pain threshold on average increasing by 1.14 s every 6 weeks (p = 0.0084, 95% confidence interval [CI] for 6-week change 0.3039–2.0178) and pain tolerance on average increasing by 2.87 s every 6 weeks (p = 0.0026, 95% CI for 6-week change 1.02–4.7277). Taper-related changes in central pain modulation were not observed, although conditioned modulation trended toward improvement by the completion of opioid taper. Similarly, no declines in function and quality of life were observed with the opioid taper, suggesting stability despite decreased opioid dose.

Conclusions

Opioid taper was associated with improvements in experimental pain responses without a decline in function and quality of life, suggestive of diminished opioid-induced hyperalgesia in this clinical sample.

Trial Registration

ClinicalTrials.gov identifier, NCT03912298.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40122-021-00348-8.

Effects of opioid rotation to buprenorphine/naloxone on pain, pain thresholds, pain tolerance, and quality of life in patients with chronic pain and opioid use disorder

ABSTRACT

Long-term opioid use in patients with chronic noncancer pain (CNCP) can lead to opioid use disorder (OUD) and has been associated with hyperalgesia and reduced quality of life (QoL). Studies suggest antihyperalgesic properties of buprenorphine, and buprenorphine or naloxone (BuNa) has shown beneficial effects on QoL in patients with OUD without CNCP. This study investigated the added value of BuNa in patients with CNCP with OUD on self-reported pain, pain thresholds, pain tolerance, and QoL. In the current study, 43 outpatients with CNCP and OUD were included for inpatient conversion from full μ-receptor agonist opioids to BuNa. Self-reported pain, pain thresholds, pain tolerance, and QoL were determined at baseline and after 2 months of follow-up, using, respectively, a Visual Analogue Scale (VAS-pain and VAS-QoL), quantitative sensory testing, and EuroQol-5 dimensions. In total, 37 participants completed the protocol, and their data were analyzed. The mean VAS-pain score decreased from 51.3 to 37.2 (27.5%, F = 3.3; P = 0.044), whereas the pressure pain threshold and electric pain threshold or tolerance increased after substitution (F = 7.8; P = 0.005 and F = 44.5; P < 0.001, respectively), as well as QoL (EuroQol-5 dimensions questionnaire: F = 10.4; P = 0.003 and VAS-QoL: F = 4.4; P = 0.043). We found that conversion of full μ-receptor agonists to BuNa, in patients with CNCP with OUD, was accompanied with lower self-reported pain, higher pain thresholds, higher pain tolerance, and improved QoL. Despite several study limitations, these data suggest that BuNa might be of value in patients with CNCP with OUD. Future studies should investigate long-term effects of BuNa in randomized trials.

The Role of Pain Catastrophizing and Pain Acceptance in Performance-Based and Self-Reported Physical Functioning in Individuals with Fibromyalgia and Obesity

Impaired physical functioning is one of the most critical consequences associated with fibromyalgia, especially when there is comorbid obesity. Psychological factors are known to contribute to perceived (i.e., subjective) physical functioning. However, physical function is a multidimensional concept encompassing both subjective and objective functioning. The contribution of psychological factors to performance-based (i.e., objective) functioning is unclear. This study aims to investigate the contribution of pain catastrophizing and pain acceptance to both self-reported and performance-based physical functioning. In this cross-sectional study, 160 participants completed self-report measures of pain catastrophizing, pain acceptance, and pain severity. A self-report measure and a performance-based test were used to assess physical functioning. Higher pain catastrophizing and lower pain acceptance were associated with poorer physical functioning at both self-reported and performance-based levels. Our results are consistent with previous evidence on the association between pain catastrophizing and pain acceptance with self-reported physical functioning. This study contributes to the current literature by providing novel insights into the role of psychological factors in performance-based physical functioning. Multidisciplinary interventions that address pain catastrophizing and pain acceptance are recommended and might be effective to improve both perceived and performance-based functioning in women with FM and obesity.

Opioid use as a predictor of pain outcomes in Iraq and Afghanistan Veterans with chronic pain: Analysis of a randomized controlled trial

OBJECTIVE

Our objectives were to: 1) assess the relationship between self-reported opioid use and baseline demographics, clinical characteristics and pain outcomes; and 2) examine whether baseline opioid use moderated the intervention effect on outcomes at 9 months.

DESIGN

We conducted a secondary analysis of data from the Evaluation of Stepped Care for Chronic Pain (ESCAPE) trial, which found stepped-care to be effective for chronic pain in military veterans.

SETTING

A post-deployment clinic and 5 general medicine clinics at a Veteran Affairs Medical Center.

SUBJECTS

241 veterans with chronic musculoskeletal pain; 220 with complete data at 9 months.

METHODS

Examination of baseline relationships and multivariable linear regression to examine baseline opioid use as a moderator of pain-related outcomes including Roland Morris Disability Questionnaire (RMDQ), Brief Pain Inventory (BPI) Interference scale, and Graded Chronic Pain Scale (GCPS) at 9 months.

RESULTS

Veterans reporting baseline opioid use (n = 80) had significantly worse RMDQ (16.0 ± 4.9 vs. 13.4 ± 4.2, P < 0.0001), GCPS (68.7 ± 12.0 vs. 65.0 ± 14.4, p = 0.049), BPI Interference (6.2 ± 2.2 vs. 5.0 ± 2.1, P < 0.0001), and depression (PHQ-9 12.5 ± 6.2 vs. 10.6 ± 5.7, p = 0.016) compared to veterans not reporting baseline opioid use. Using multivariable modeling we found that baseline opioid use moderated the intervention effect on pain-related disability (RMDQ) at 9 months (interaction Beta = -3.88, p = 0.0064), but not pain intensity or interference.

CONCLUSIONS

In a stepped-care trial for pain, patients reporting baseline opioid use had greater improvement in pain disability at 9 months compared to patients not reporting opioid use.

Impact of opioid dose escalation on pain intensity: a retrospective cohort study

Prescribers are often confronted with the decision to escalate opioid doses to achieve adequate analgesia. Understanding the impact of dose escalation on pain intensity is warranted. Using a retrospective cohort study design, Veterans with chronic pain and chronic opioid therapy were identified. Opioid dose escalators (>20% increase in average morphine milligram equivalent daily dose) were compared with dose maintainers (±20% change in average morphine milligram equivalent daily dose) assessed over 2 consecutive 6-month windows. Pain intensity was measured by the Numeric Rating Scale. The primary analyses used linear repeated-measures models among a 1:1 matched sample of escalators and maintainers matched on propensity score and within ±180 days of the index date. Sensitivity analyses were conducted using adjusted linear repeated-measures models with and without incorporating stabilized inverse probability of treatment weighting. There were 32,420 dose maintainers and 20,767 dose escalators identified with 19,358 (93%) matched pairs. Pain scores were persistently higher among dose escalators at each 90-day period after the index date (0-90 days after index date: dose escalators: 4.68, 95% confidence interval [CI]: 4.64-4.72 dose maintainers: 4.32, 95% CI: 4.28-4.36, P < 0.0001; 91-180 days after index date: dose escalators: 4.53, 95% CI: 4.49-4.57; dose maintainers: 4.25, 95% CI: 4.22-4.29, P < 0.0001) but were not different in the 90 days before the index date (dose escalators: 4.64, 95% CI: 4.61-4.68; dose maintainers: 4.59, 95% CI: 4.55-4.63, P = 0.0551). Sensitivity analyses provided similar results as the primary analyses. Opioid dose escalation among patients with chronic pain is not associated with improvements in Numeric Rating Scale pain scores.

Benefits and Harms of Long-term Opioid Dose Reduction or Discontinuation in Patients with Chronic Pain: a Rapid Review

BACKGROUND

Many clinicians are reevaluating the use of long-term opioid therapy (LTOT) for chronic pain in response to the opioid crisis and calls from organizations including the Centers for Disease Control & Prevention to limit prescribing of high-dose opioids. However, this practice change is occurring largely in the absence of data regarding patient outcomes. A 2017 systematic review found inconclusive evidence on the impact of LTOT dose reduction and discontinuation on pain severity and function, quality of life, withdrawal symptoms, substance abuse, and adverse effects. This rapid systematic review provides an updated evidence synthesis of patient outcomes following LTOT dose reduction including serious harms such as overdose and suicide.

METHODS

We systematically searched numerous bibliographic databases from January 2017 (the end search date of the 2017 systematic review) through May 2020. One reviewer used prespecified criteria to assess articles for inclusion, evaluate study quality, abstract data, and grade strength of evidence, with a second reviewer checking.

RESULTS

We included 49 studies-1 systematic review, 34 studies included in that systematic review, and 14 new studies. We prioritized evidence synthesis of 19 studies with the most applicability to the Veteran population and outpatient settings. Among these studies, improvements in mean pain scores were common among patients tapering opioids while participating in intensive multimodal pain interventions and mostly unchanged with less intensive or nonspecific co-interventions. Our confidence in these findings is low due to methodological limitations of the studies. Observational data suggests that serious harms such as opioid overdose and suicidal ideation can occur following opioid dose reduction or discontinuation, but the incidence of these harms at the population level is unknown.

DISCUSSION

The net balance of benefits and harms of LTOT dose reduction for patients with chronic pain is unclear. Clinicians should closely monitor patients during the tapering process given the potential for harm.

Impact of opioid dose escalation on the development of substance use disorders, accidents, self-inflicted injuries, opioid overdoses and alcohol and non-opioid drug-related overdoses: a retrospective cohort study

AIM

To understand the potential harmful effects of dose escalation among patients with chronic, non-cancer pain (CNCP) on chronic opioid therapy.

DESIGN

Retrospective cohort study.

SETTING

United States Veterans Healthcare Administration.

PARTICIPANTS

Veterans with CNCP and on chronic opioid therapy were identified using data from fiscal years 2008-15. The Veteran sample was approximately 90% male and 70% white.

MEASUREMENTS

Dose escalators [increase of > 20% average morphine milligram equivalent (MME) daily dose] were compared with dose maintainers (change of ±20% average MME daily dose). A composite measure of subsequent substance use disorders (SUDs: opioid, non-opioid and alcohol use disorders) and opioid-related adverse outcomes (AOs: accidents resulting in wounds/injuries, opioid-related and alcohol and non-opioid medication-related accidents and overdoses, self-inflicted injuries) as well as the individual SUDs and AOs was examined. The primary analyses were conducted among a 1 : 1 matched sample of escalators and maintainers matched on propensity score and index date. Propensity scores were generated using demographic characteristics, medical comorbidities, medication and health-care utilization characteristics. Subgroup analyses were conducted by quartile of the propensity score. Sensitivity analyses were conducted using adjusted logistic regression, logistic regression using stabilized inverse probability of treatment weighting (SIPTW) and instrumental variable (IV) models using geographic variation in opioid dose escalation as the IV.

FINDINGS

There were 32 420 maintainers and 20 767 escalators resulting in 19 358 (93.2%) matched pairs. Composite AOs [odds ratio (OR) = 1.31, 95% confidence interval (CI) = 1.23, 1.40], composite SUDs (OR = 1.31, 95% CI = 1.22, 1.41) and individual SUD and AO subtypes were higher among dose escalators, except for opioid-related accidents and overdoses and violence-related injuries. Subgroup analyses within the propensity score quartiles found similar results. Sensitivity analyses with the adjusted and SIPTW logistic regressions found similar results to the primary analyses for all outcomes except for opioid-related accidents and overdoses, which were found to be significantly higher among escalators. Sensitivity analyses with IV models provided mixed results with SUDs and the individual types of AOs.

CONCLUSION

Escalating the opioid dose for those with chronic, non-cancer pain is associated with increased risks of substance use disorder and opioid-related adverse outcomes.