Correlates of pain in an in-treatment sample of opioid-dependent people

Pain in people seeking and receiving opioid agonist treatment: A systematic review and meta-analysis of prevalence and correlates

BACKGROUND AND AIMS

People with opioid use disorder (OUD) commonly experience pain including chronic pain. Despite the high prevalence, few studies have systematically examined the prevalence and correlates of pain among people seeking or receiving opioid agonist treatment (OAT) for OUD. This review aimed to determine the prevalence of pain in this population globally, and estimate the association between chronic pain and other demographic and clinical characteristics.

METHODS

Electronic searches were conducted in three databases (Medline, Embase and PsycINFO) from the inception until October 2022. Eligible studies reported prevalence rates of current and/or chronic pain. Meta-analyses examining the main prevalence estimates were conducted by Stata SE 18.0, and comorbid clinical conditions were analysed by Review Manager 5.4.

RESULTS

Fifty-six studies (n participants = 35 267) from sixty-seven publications were included. Prevalence estimates of current and chronic pain were reported in 27 (48.2%) and 40 studies (71.4%), respectively. Most studies were conducted in North America (71.4%, n = 40) and used cross-sectional designs (64.3%, n = 36). Meta-analyses revealed a pooled prevalence of 60.0% (95% confidence interval [CI]: 52.0-68.0) for current pain and 44.0% [95% CI: 40.0-49.0] for chronic pain. Chronic pain was positively associated with older age (mean deviation of mean age: 2.39 years, 95% CI: 1.40-3.37; I2 = 43%), unemployment (odds ratio [OR] = 0.57, 95% CI: 0.42-0.76; I2 = 78%), more severe mental health symptoms (e.g. more severe depression (standardised mean difference [SMD] of mean scores: 0.45, 95% CI: 0.20-0.70; I2 = 48%) and anxiety symptoms (SMD: 0.52, 95% CI: 0.17-0.88; I2 = 67%), and hepatitis C (OR = 1.41, 95% CI: 1.03-1.94; I2 = 0%). No association was observed between chronic pain and the onset and type of OAT, geographic location, study design, survey year, participant age or use of specific pain assessment tools.

CONCLUSIONS

There appears to be a high prevalence of pain among people seeking or receiving opioid agonist treatment for opioid use disorder compared with the general population, with positive associations for older age, unemployment, hepatitis C and the severity of some mental health symptoms.

Health harms of non-medical prescription opioid use: A systematic review

ISSUES

Non-medical prescription opioid use (NMPOU) contributes substantially to the global burden of morbidity. However, no systematic assessment of the scientific literature on the associations between NMPOU and health outcomes has yet been undertaken.

APPROACH

We undertook a systematic review evaluating health outcomes related to NMPOU based on ICD-10 clinical domains. We searched 13 electronic databases for original research articles until 1 July 2021. We employed an adaptation of the Oxford Centre for Evidence-Based Medicine 'Levels of Evidence' scale to assess study quality.

KEY FINDINGS

Overall, 182 studies were included. The evidence base was largest on the association between NMPOU and mental and behavioural disorders; 71% (129) studies reported on these outcomes. Less evidence exists on the association of NMPOU with infectious disease outcomes (26; 14%), and on external causes of morbidity and mortality, with 13 (7%) studies assessing its association with intentional self-harm and 1 study assessing its association with assault (<1%).

IMPLICATIONS

A large body of evidence has identified associations between NMPOU and opioid use disorder as well as on fatal and non-fatal overdose. We found equivocal evidence on the association between NMPOU and the acquisition of HIV, hepatitis C and other infectious diseases. We identified weak evidence regarding the potential association between NMPOU and intentional self-harm, suicidal ideation and assault.

DISCUSSION AND CONCLUSIONS

Findings may inform the prevention of harms associated with NMPOU, although higher-quality research is needed to characterise the association between NMPOU and the full spectrum of physical and mental health disorders.

Prevalence and Characteristics of Chronic Pain in Buprenorphine and Methadone-Maintained Patients

Chronic pain and substance use disorders frequently co-occur. Indeed, chronic pain is highly prevalent, affecting 23-68% of patients receiving opioid agonist treatments (OAT) worldwide. The majority of available estimates come from American studies, but data are still lacking in Europe. We aim to provide European estimates of the prevalence of chronic pain in patients receiving OAT using French data, since France is the first European country in terms of number of patients with OAT. The secondary objectives were to characterize the features and management of chronic pain, as well identify associated risk factors. We conducted a multicenter, cross-sectional study, recruiting patients treated either with buprenorphine or methadone in 19 French addiction centers, from May to July 2016. All participants had to complete a semi-directed questionnaire that collected sociodemographic and medical data, pain characteristics, and licit or illicit drug consumption. In total, 509 patients were included. The prevalence of chronic pain was estimated at 33.2% (95% CI: 29.1-37.3). Compared to non-chronic pain patients, chronic pain patients were older (38.4 vs. 36.1 years, p = 0.006), were more unemployed (66 vs. 52%, p = 0.003), had more psychiatric comorbidities (50 vs. 39%, p = 0.02), and split their OAT for pain management more frequently (24 vs. 7%, p = 0.009). Pain intensity was moderate or severe in 75% of chronic pain patients. Among patients with chronic pain, 15.4% were not prescribed, and did not self-medicate with, any analgesic drugs, 52.1% were prescribed analgesics (non-opioid analgesics, 76.3%; codeine, tramadol, opium, 27.2%; and morphine, fentanyl, oxycodone, 11.8%), and 32.5% exclusively self-medicated with analgesics. Moreover, 20.1% of patients with chronic pain also used illicit drugs for pain relief. On multivariate analysis, variables that remained significantly associated with chronic pain were age [OR = 1.03 (95% CI: 1.00-1.05], p = 0.02], anxiety [OR = 1.52 (1.15-2.02), p = 0.003], and depression [OR = 1.25 (1.00-1.55), p = 0.05]. Chronic pain is a highly prevalent condition in patients receiving OAT, and its appropriate management remains uncertain, since insufficient relief and frequent additional self-medications with analgesics or illicit drugs were reported by these patients. Increased awareness among caregivers is urgently needed regarding a systematic and careful assessment, along with an adequate management of chronic pain in patients receiving OAT.

Chronic Pain Opioid-Maintained Patients Receive Less Analgesic Opioid Prescriptions

Treating pain and opioid use disorder represents a clinical challenge. While most studies that have assessed opioid analgesic use in opioid substitution treatment (OST) patients primarily address opioid analgesic misuse (1, 2), only few studies focused on OST patients assessed the prescription of analgesic opioids for chronic pain. We sought to compare the prevalence of analgesic opioid prescription (AOP) in two groups of chronic non-cancer pain (CNCP) patients: OST patients vs. the general population. This was a population-based cross-sectional study based on the French national healthcare claims database SNIIRAM (Système National d'Informations Inter-Régimes de l'Assurance Maladie) covering over 66 million people (98.8% of the French population). Overall, 67,173 participants ≥15 years old undergoing continuous OST in 2015 ("OST patients" group) were included and age- and gender-matched by means of a 1:1 ratio with 67,173 patients without OST ("control" group). In each group, patients with cancer conditions were excluded and those having received opioid and non-opioid analgesics for at least 3 months were identified (CNCP patients). Compared to control patients, CNCP OST patients received less AOP (47.8 vs. 68.0%, p < 0.0001) and more often non-opioid prescription (52.2 vs. 32.0%, p < 0.0001). In multivariate analysis, CNCP OST patients were 2.7 times less likely to be prescribed analgesic opioids (adjusted odds ratio [OR] = 2.7 [2.42-3.01], p < 0.0001) than control patients. AOP correlated in CNCP OST patients with: age ≤ 40 years old, female gender, low-income status, methadone-maintained treatment, mental health disorder, hepatitis C virus (HCV) infection, and alcohol abuse disorder. Opioid analgesics were less often prescribed in CNCP OST patients. AOP prevalence was 2.7-fold lower than in the general population. Chronic pain management in OST patients needs to be reinforced through additional physician training and a multidisciplinary approach.

Pain in methadone patients: Time to address undertreatment and suicide risk (ANRS-Methaville trial)

Background

Pain in opioid-dependent patients is common but data measuring the course of pain (and its correlates) using validated scales in patients initiating methadone treatment are sparse. We aimed to assess pain and its interference in daily life, associated correlates, and undertreatment before and during methadone treatment.

Methods

This is a secondary analysis using longitudinal data of a randomized trial comparing two methadone initiation models. We assessed the effect of methadone initiation and other correlates on pain intensity and interference (using the Brief Pain Inventory) at months 0, 6 and 12 using a mixed multinomial logistic regression model.

Results

The study group comprised 168 patients who had data for either pain intensity or interference for at least one visit. Moderate to severe pain was reported in 12.9% of patients at M0, 5.4% at M6 and 7.3% at M12. Substantial interference with daily functioning was reported in 36.0% at M0, 14.5% at M6 and 17.1% at M12. Of the 98 visits where patients reported moderate to severe pain or substantial interference, 55.1% reported no treatment for pain relief, non-opioid analgesics were reported by 34.7%, opioid analgesics by 3.1% and both opioid and non-opioid analgesics by 7.1%. Methadone was associated with decreased pain intensity at 6 months (OR = 0.29, p = 0.04) and 12 months (OR = 0.30, p = 0.05) of follow-up and tended to be associated with substantial pain interference. Suicide risk was associated with both pain intensity and pain interference.

Conclusions

Methadone in opioid-dependent patients can reduce pain. However, undertreatment of pain in methadone patients remains a major clinical concern. Patients with pain are at higher risk of suicide. Adequate screening and management of pain in this population is a priority and needs to be integrated into routine comprehensive care.

Pain Among High-Risk Patients on Methadone Maintenance Treatment

The complexity of treating concurrent pain and opioid dependence among many methadone-maintained individuals presents a major challenge in many clinical settings. Furthermore, recent expert guidelines have called for increased research on the safety of methadone in the context of chronic pain. This study explores the prevalence and correlates of pain among a prospective cohort of people who use illicit drugs in Vancouver, British Columbia, Canada, who reported enrollment in methadone maintenance treatment (MMT) between 2011 and 2014. Among the 823 participants eligible for this analysis, 338 (40.9%) reported moderate pain and 91 (11.1%) reported extreme pain at the first study visit. In multivariable, generalized, linear mixed model analyses, higher pain severity was positively and independently associated with self-managing pain (adjusted odds ratio [AOR] 2.15, 95% confidence interval [CI] 1.77-2.60), patient perception of methadone dose being too low (AOR 1.82, 95% CI 1.41-2.34), older age (AOR 1.31, 95% CI 1.13-1.51), having a physical disability (AOR 4.59, 95% CI 3.73-5.64), having ever been diagnosed with a mental illness (AOR 1.44, 95% CI 1.13-1.84), white ethnicity (AOR 1.42, 95% CI 1.10-1.83), and marijuana use (AOR 1.25, 95% CI 1.02-1.52). These findings suggest several areas for clinical intervention, particularly related to patient education and alternative analgesic approaches for MMT patients experiencing pain. Perspective: To better understand the complexity of concurrent pain and opioid dependency among individuals on methadone maintenance treatment, this article describes the prevalence and correlates of higher pain severity among methadone-maintained people who use illicit drugs. Patients on methadone with comorbid pain may benefit from education and alternative analgesic approaches.

Longitudinal analysis of pain and illicit drug use behaviors in outpatients on methadone maintenance

BACKGROUND

Little is known about the experience of chronic pain and the occurrence of illicit drug use behaviors in the population enrolled in methadone maintenance treatment (MMT) programs.

METHODS

This is a secondary analysis of longitudinal data from two MMT samples enrolled in a randomized controlled trial of hepatitis care coordination. Patients completed pain, illicit drug use, and other questionnaires at baseline and 3, 9, and 12 months later. Associations were sought over time between the presence or absence of clinically significant pain (average daily pain ≥ 4 or mean pain interference ≥ 4 during the past week) and current illicit drug use (i.e., non-therapeutic opioid, cocaine or amphetamine use identified from self-report or urine drug screening).

RESULTS

Of 404 patients providing complete data, within-patient variability in pain and illicit drug use was high across the four assessment periods. While 263 denied pain at baseline, 118 (44.9%) later experienced clinically significant pain during ≥ 1 follow-up assessments. Of 180 patients (44.6%) without evidence of illicit drug use at baseline, only 109 (27.0%) had similar negative drug use at all follow-up assessments. Across four assessment periods, there was no significant association between pain group status and current illicit drug use.

CONCLUSIONS

This one-year longitudinal analysis did not identify a significant association between pain and illicit drug use in MMT populations. This finding conflicts with some earlier investigations and underscores the need for additional studies to clarify the complex association between pain and substance use disorders in patients in MMT program settings.

Patterns of, and Factors Associated With, Illicit Pharmaceutical Opioid Analgesic Use in a Prospective Cohort of People Who Inject Drugs in Melbourne, Australia

BACKGROUND

People who inject drugs (PWID) are a key population engaging in pharmaceutical opioid analgesic (PO) use, yet little is known about patterns of illicit PO use among this group.

OBJECTIVES

The aims of this research were to measure the prevalence and frequency of lifetime and past-month illicit PO use and injection in a sample of regular PWID, to examine patterns of past-month illicit PO use within individuals over time, and to identify factors independently associated with past-month illicit PO use.

METHODS

Data were drawn from a prospective cohort study of regular PWID (N = 666) in Melbourne, Australia. Data from five waves of annual data collection (including baseline) were analyzed descriptively and using generalized estimating equations (GEE).

RESULTS

At baseline, 59% of participants reported lifetime illicit PO use and 20% reported past-month use, predominantly through injecting. Most illicit PO users at baseline transitioned to nonuse of illicit POs across the study period. In multivariable GEE analysis, factors associated with past-month illicit PO use included past-year arrest [adjusted odds ratio (AOR): 1.39], opioids other than heroin as drug of choice (AOR: 5.14), experiencing poorer physical health (AOR: 0.98) and a range of other drug use variables.

CONCLUSIONS

We found little evidence of ongoing illicit PO use among those followed up, with illicit PO use linked to polydrug use more broadly. Nonetheless, trends in illicit PO use among PWID should continue to be monitored and harm reduction interventions implemented to reduce the associated public health risks.