Elevated pain sensitivity in chronic pain patients at risk for opioid misuse

Painful After-Sensations in Fibromyalgia are Linked to Catastrophizing and Differences in Brain Response in the Medial Temporal Lobe

Fibromyalgia (FM) is a complex syndrome characterized by chronic widespread pain, hyperalgesia, and other disabling symptoms. Although the brain response to experimental pain in FM patients has been the object of intense investigation, the biological underpinnings of painful after-sensations (PAS), and their relation to negative affect have received little attention. In this cross-sectional cohort study, subjects with FM (n = 53) and healthy controls (n = 17) were assessed for PAS using exposure to a sustained, moderately painful cuff stimulus to the leg, individually calibrated to a target pain intensity of 40 of 100. Despite requiring lower cuff pressures to achieve the target pain level, FM patients reported more pronounced PAS 15 seconds after the end of cuff stimulation, which correlated positively with clinical pain scores. Functional magnetic resonance imaging revealed reduced deactivation of the medial temporal lobe (MTL; amygdala, hippocampus, parahippocampal gyrus) in FM patients, during pain stimulation, as well as in the ensuing poststimulation period, when PAS are experienced. Moreover, the functional magnetic resonance imaging signal measured during the poststimulation period in the MTL, as well as in the insular and anterior middle cingulate and medial prefrontal cortices, correlated with the severity of reported PAS by FM patients. These results suggest that the MTL plays a role in PAS in FM patients.

PERSPECTIVE

PAS are more common and severe in FM, and are associated with clinical pain and catastrophizing. PAS severity is also associated with less MTL deactivation, suggesting that the MTL, a core node of the default mode network, may be important in the prolongation of pain sensation in FM.

Pain sensitivity and analgesic use among 10,486 adults: the Tromsø study

Background

Increased pain sensitivity is a putative risk factor for chronic pain and consequently for analgesic use. Conversely, analgesic use may be a cause of increased pain sensitivity, e.g., through opioid-induced hyperalgesia. We aimed to study the association between pain sensitivity and analgesic use in a general population, and to test the hypothesis that increased baseline pain sensitivity is a risk factor for future persistent analgesic use.

Methods

The Tromsø Study (2007–08), a population-based health study, was linked with eight years of prescription data from the Norwegian Prescription Database. The cold pressor test was completed in 10,486 participants aged 30+ years, and we used cold pressor endurance time as a proxy measure of pain sensitivity. Cross-sectional associations with different measures of analgesic use were assessed. Furthermore, a cohort of 9,657 persons was followed for 4.5 years.

Results

In the cross-sectional analysis, increased pain sensitivity was associated with analgesic use; regular users of opioids alone were more pain sensitive than regular users of non-opioid analgesics. Increased baseline pain sensitivity was a risk factor for persistent analgesic use, i.e., using non-steroidal anti-inflammatory drugs, paracetamol, or opioids for ≥ 90 days and proportion-of-days-covered ≥ 40% (HR = 1.22, 95% CI 1.06-1.40), although not statistical significant after confounder adjustment.

Conclusions

Increased pain sensitivity was associated with analgesic use in general, and reduced pain tolerance was found for both opioid and non-opioid analgesic users. The data suggest that hyperalgesia is an effect of analgesics, whereas pain tolerance has little impact on future analgesic use.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0149-2) contains supplementary material, which is available to authorized users.

Temporal preference in individuals reporting chronic pain: discounting of delayed pain-related and monetary outcomes

Opioid therapy for pain is associated with an increased risk for substance use disorders. This study's purpose was to determine the association between opioid misuse propensity (Screener and Opioid Assessment for Patients in Pain-Revised) and delay discounting (DD), a behavioral process linked to substance use disorders, which quantifies the extent to which outcomes are devalued because of their delay. Participants reporting chronic pain (N = 249) answered pain and opioid use questions and then completed 4 DD tasks. Each of these tasks assessed either money or pain consequences, framed as either rewards or punishments. Each task involved hypothetical choices between immediate smaller vs delayed larger consequences. The extant Monetary Choice Questionnaire assessed DD of money rewards, and a modified version assessed discounting of money losses (immediate smaller loss vs larger delayed loss). Based on the Monetary Choice Questionnaire, the novel Pain Relief Choice Questionnaire assessed choices between an immediate short duration of pain relief vs a longer duration of pain relief. Similarly, the novel Additional Pain Choice Questionnaire assessed choices between an immediate short duration of additional pain vs a longer duration of additional pain. Discounting of both additional pain and money losses were significantly associated with high Screener and Opioid Assessment for Patients in Pain-Revised scores-indicating participants at greatest risk for opioid misuse discount future punishments rather than future rewards compared with those at low risk. Measures of DD may have promise in more accurately identifying individuals at highest risk for opioid misuse during chronic opioid therapy.

Influence of opioid-related side effects on disability, mood, and opioid misuse risk among patients with chronic pain in primary care

Patients who reported significant medication-related side effects reported greater activity interference, negative affect, catastrophizing, and opioid misuse risk compared with those with fewer side effects.

Background:

There is increasing concern among primary care practitioners about the use of opioids for chronic pain, including their adverse effects, but little attention has been given to how reports of side effects from prescription medication can contribute to outcomes among patients with chronic pain. The aim of this study was to investigate the impact of frequently reported side effects on mood, disability, and opioid misuse in patients with chronic pain prescribed opioids within primary care.

Methods:

Two hundred (N = 200) patients with chronic pain taking opioids for pain were recruited into the study. All patients completed baseline measures and a monthly side effects checklist once a month for 6 months. Patients were divided evenly based on a median split of the number of endorsed side effects over 6 months. The subjects repeated the baseline measures at the end of the study period.

Results:

Over time, reports of medication side effects tended to decrease, but differences in frequency of reported side effects from baseline to follow-up (6-month time) were not significant, and the order of the frequency of the reported side effects remained similar. Patients who reported significant medication-related adverse effects reported significantly greater activity interference, negative affect, and catastrophizing compared with those with fewer side effects (P < 0.01). In addition, those patients with pain who reported more side effects showed significantly higher scores on opioid misuse risk (P < 0.001).

Discussion:

This study demonstrates the important role of monitoring medication-related side effects among patients with chronic pain who are prescribed opioid medication for pain within primary care.

Evaluation of How Depression and Anxiety Mediate the Relationship Between Pain Catastrophizing and Prescription Opioid Misuse in a Chronic Pain Population

OBJECTIVE

We investigated the extent to which anxiety and depression mediate the relationship between pain catastrophizing and the risk of prescription opioid misuse in chronic pain patients.

METHODS

215 patients with chronic occupational musculoskeletal disorders completed self-report measures upon admission to a functional restorational program. A bootstrap multivariate regression analysis was conducted to assess how depression and anxiety mediated the relationship between pain catastrophizing and prescription opioid misuse.

RESULTS

Catastrophizing, anxiety, and depression predicted higher risk for prescription opioid misuse. Furthermore, anxiety and depression acted as mediators while controlling for the effects of gender and age. Finally, it was found that the effects of catastrophizing on risk for prescription opioid misuse were completely eliminated by those of depression.

CONCLUSION

Due to the partially independent relationship of anxiety and catastrophizing, it is recommended that treatments for chronic pain patients employ techniques addressing both behaviors. The relationship between depression and catastrophizing requires more research since it was observed that their effects were confounded.

The Role of Psychosocial Processes in the Development and Maintenance of Chronic Pain

The recently proposed Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION)-American Pain Society (APS) Pain Taxonomy (AAPT) provides an evidence-based, multidimensional, chronic pain classification system. Psychosocial factors play a crucial role within several dimensions of the taxonomy. In this article, we discuss the evaluation of psychosocial factors that influence the diagnosis and trajectory of chronic pain disorders. We review studies in individuals with a variety of persistent pain conditions, and describe evidence that psychosocial variables play key roles in conferring risk for the development of pain, in shaping long-term pain-related adjustment, and in modulating pain treatment outcomes. We consider "general" psychosocial variables such as negative affect, childhood trauma, and social support, as well as "pain-specific" psychosocial variables that include pain-related catastrophizing, self-efficacy for managing pain, and pain-related coping. Collectively, the complexity and profound variability in chronic pain highlights the need to better understand the multidimensional array of interacting forces that determine the trajectory of chronic pain conditions.

PERSPECTIVE

The AAPT is an evidence-based chronic pain classification system in which psychosocial concepts and processes are essential in understanding the development of chronic pain and its effects. In this article we review psychosocial processes that influence the onset, exacerbation, and maintenance of chronic pain disorders.

Suicidal ideation is associated with individual differences in prescription opioid craving and cue-reactivity among chronic pain patients

Given that chronic pain patients experience significant rates of suicidal ideation and suicide attempts, access to prescription opioids compounds the risk of death by suicide. These patients may experience heightened opioid craving and exhibit increased cue-reactivity to stimuli associated with past opioid use when suicidal ideation produces negative affective states. Because both opioids and suicidal behavior are used to alleviate emotional and physical pain through a process of negative reinforcement, elucidating factors that mediate this association may yield insight into suicide risk among chronic pain patients. This study examined the relationship between suicidal ideation and opioid craving and cue-reactivity, and tested opioid self-medication as a mediator of associations between those factors after controlling for the impact of pain severity. A sample of 115 chronic pain patients provided demographic and clinical information on the Obsessive Compulsive Drug Use Scale, the Current Opioid Misuse Measure, and the Brief Pain Inventory before completing an opioid dot probe task in which heart rate variability was recorded. As hypothesized, suicidal ideation was positively correlated with subjective opioid craving and physiological cue-reactivity. Self-medication significantly mediated the association between suicidal ideation, craving, and cue-reactivity. As opioids relieve the emotional pain linked with suicidal thoughts, chronic pain patients with higher levels of suicidal ideation may experience more intense opioid craving and exhibit heightened physiological cue-reactivity when compared to patients with low levels of suicidal ideation.

Distress Intolerance and Prescription Opioid Misuse Among Patients With Chronic Pain

The risk for misuse of opioid medications is a significant challenge in the management of chronic pain. The identification of those who may be at greater risk for misusing opioids is needed to facilitate closer monitoring of high-risk subgroups, and may help to identify therapeutic targets for mitigating this risk. The aim of this study was to examine whether distress intolerance-the perceived or actual inability to manage negative emotional and somatic states-was associated with opioid misuse in those with chronic pain. A sample of 51 participants prescribed opioid analgesics for chronic back or neck pain were recruited for a 1-time laboratory study. Participants completed measures of distress intolerance and opioid misuse, and a quantitative sensory testing battery. Results suggested that distress intolerance was associated with opioid misuse, even controlling for pain severity and negative affect. Distress intolerance was not associated with pain severity, threshold, or tolerance, but was associated with self-reported anxiety and stress after noxious stimuli. This study found robust differences in distress intolerance between adults with chronic pain with and without opioid medication misuse. Distress intolerance may be a relevant marker of risk for opioid misuse among those with chronic pain.

PERSPECTIVE

This study demonstrated that distress intolerance was associated with opioid misuse in adults with chronic pain who were prescribed opioids. Distress intolerance can be modified with treatment, and thus may be relevant not only for identification of risk for opioid misuse, but also for mitigation of this risk.

Changes in Pain Sensitivity and Pain Modulation During Oral Opioid Treatment: The Impact of Negative Affect

OBJECTIVE

Opioids are frequently prescribed for chronic low back pain (CLBP), but there are broad individual differences in the benefits and risks of opioid therapy, including the development opioid-induced hyperalgesia. This study examined quantitative sensory testing (QST) data among a group of CLBP patients undergoing sustained oral opioid treatment. We investigated whether individual differences in psychological characteristics were related to opioid-induced changes in pain perception and pain modulation.

DESIGN

The six-month, open-label trial evaluated patients with low to high levels of negative affect (e.g., symptoms of distress, depression and anxiety); participants underwent QST at baseline (prior to initiating treatment) and during oral opioid treatment.

SETTING

A chronic pain management center.

PATIENTS

The 31 study participants had chronic discogenic back pain, with a pain intensity rating >3/10. Participants were divided into groups with high vs. low levels of Negative Affect (NA).

RESULTS

In the previously-published manuscript describing the clinical outcomes of the trial, high NA patients achieved only about half of the analgesic effect observed in the low NA group (Wasan AD, Michna E, Edwards RR, et al. Psychiatric comorbidity is associated prospectively with diminished opioid analgesia and increased opioid misuse in patients with chronic low back pain. Anesthesiology 2015;123:861-72). The QST findings reported here suggested that tolerance to experimental (cold pressor) pain and conditioned pain modulation tended to decrease in the high NA group over the course of opioid treatment, while temporal summation of mechanical pain declined in the low NA group.

CONCLUSIONS

These results reveal that while the low NA group seemed to exhibit a generally adaptive, analgesic pattern of changes during opioid management, the high NA group showed a pattern more consistent with opioid-induced hyperalgesic processes. A greater susceptibility to hyperalgesia-promoting changes in pain modulation among patients with high levels of distress may contribute to a lower degree of benefit from opioid treatment in high NA patients.

Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain

The primary afferent nociceptor was used as a model system to study mechanisms of pain induced by chronic opioid administration. Repeated intradermal injection of the selective mu-opioid receptor (MOR) agonist DAMGO induced mechanical hyperalgesia and marked prolongation of prostaglandin E2 (PGE2) hyperalgesia, a key feature of hyperalgesic priming. However, in contrast to prior studies of priming induced by receptor-mediated (i.e., TNFα, NGF, or IL-6 receptor) or direct activation of protein kinase Cε (PKCε), the pronociceptive effects of PGE2 in DAMGO-treated rats demonstrated the following: (1) rapid induction (4 h compared with 3 d); (2) protein kinase A (PKA), rather than PKCε, dependence; (3) prolongation of hyperalgesia induced by an activator of PKA, 8-bromo cAMP; (4) failure to be reversed by a protein translation inhibitor; (5) priming in females as well as in males; and (6) lack of dependence on the isolectin B4-positive nociceptor. These studies demonstrate a novel form of hyperalgesic priming induced by repeated administration of an agonist at the Gi-protein-coupled MOR to the peripheral terminal of the nociceptor. Significance statement: The current study demonstrates the molecular mechanisms involved in the sensitization of nociceptors produced by repeated activation of mu-opioid receptors and contributes to our understanding of the painful condition observed in patients submitted to chronic use of opioids.

The affective dimension of pain as a risk factor for drug and alcohol addiction

Addiction, or substance use disorder (SUD), is a devastating psychiatric disease composed of multiple elemental features. As a biobehavioral disorder, escalation of drug and/or alcohol intake is both a cause and consequence of molecular neuroadaptations in central brain reinforcement circuitry. Multiple mesolimbic areas mediate a host of negative affective and motivational symptoms that appear to be central to the addiction process. Brain stress- and reinforcement-related regions such as the central amygdala (CeA), prefrontal cortex (PFC), and nucleus accumbens (NAc) also serve as central processors of ascending nociceptive input. We hypothesize that a sensitization of brain mechanisms underlying the processing of persistent and maladaptive pain contributes to a composite negative affective state to drive the enduring, relapsing nature of addiction, particularly in the case of alcohol and opioid use disorder. At the neurochemical level, pain activates central stress-related neuropeptide signaling, including the dynorphin and corticotropin-releasing factor (CRF) systems, and by this process may facilitate negative affect and escalated drug and alcohol use over time. Importantly, the widespread prevalence of unresolved pain and associated affective dysregulation in clinical populations highlights the need for more effective analgesic medications with reduced potential for tolerance and dependence. The burgeoning epidemic of prescription opioid abuse also demands a closer investigation into the neurobiological mechanisms of how pain treatment could potentially represent a significant risk factor for addiction in vulnerable populations. Finally, the continuing convergence of sensory and affective neuroscience fields is expected to generate insight into the critical balance between pain relief and addiction liability, as well as provide more effective therapeutic strategies for chronic pain and addiction.

Thought suppression as a mediator of the association between depressed mood and prescription opioid craving among chronic pain patients

Emerging research suggests that prescription opioid craving is associated with negative mood and depression, but less is known about cognitive factors linking depressive symptoms to opioid craving among adults with chronic pain. The present cross-sectional study examined thought suppression as a mediator of the relation between depression and prescription opioid craving in a sample of chronic pain patients receiving long-term opioid pharmacotherapy. Data were obtained from 115 chronic pain patients recruited from primary care, pain, and neurology clinics who had taken prescription opioids daily or nearly every day for ≥90 days prior to assessment. In this sample, 60 % of participants met DSM-IV criteria for current major depressive disorder. Depressed mood (r = .36, p < .001) and thought suppression (r = .33, p < .001) were significantly correlated with opioid craving. Multivariate path analyses with bootstrapping indicated the presence of a significant indirect effect of thought suppression on the association between depressed mood and opioid craving (indirect effect = .09, 95 % CI .01, .20). Sensitivity analyses showed a similar indirect effect of suppression linking major depressive disorder diagnosis and opioid craving. Attempts to suppress distressing and intrusive thoughts may result in increased craving to use opioids among chronic pain patients with depressive symptoms. Results highlight the need for interventions that mitigate thought suppression among adults with pain and mood disorders.

Hepatitis C virus infection and pain sensitivity in patients on methadone or buprenorphine maintenance therapy for opioid use disorders

BACKGROUND

Patients with opioid use disorders on opioid agonist therapy (OAT) have lower pain tolerance compared to controls. While chronic viral infections such as HCV and HIV have been associated with chronic pain in this population, no studies have examined their impact on pain sensitivity.

METHODS

We recruited 106 adults (41 uninfected controls; 40 HCV mono-infected; and 25 HCV/HIV co-infected) on buprenorphine or methadone to assess whether HCV infection (with or without HIV) was associated with increased experimental pain sensitivity and self-reported pain. The primary outcome was cold pain tolerance assessed by cold-pressor test. Secondary outcomes were cold pain thresholds, wind-up ratios to repetitive mechanical stimulation (i.e., temporal summation) and acute and chronic pain. Multivariable regression models evaluated associations between viral infection status and outcomes, adjusting for other factors.

RESULTS

No significant differences were detected across groups for primary or secondary outcomes. Adjusted mean cold pain tolerance was 25.7 (uninfected controls) vs. 26.8 (HCV mono-infection) vs. 25.3 (HCV/HIV co-infection) seconds (global p-value=0.93). Current pain appeared more prevalent among HCV mono-infected (93%) compared to HCV/HIV co-infected participants (76%) and uninfected controls (80%), as did chronic pain (77% vs. 64% vs. 61%, respectively). However, differences were not statistically significant in multivariable models.

CONCLUSION

This study did not detect an association between HCV infection and increased sensitivity to pain among adults with and without HIV who were treated with buprenorphine or methadone for opioid use disorders. Results reinforce that pain and hyperalgesia are common problems in this population.

The Contribution of Differential Opioid Responsiveness to Identification of Opioid Risk in Chronic Pain Patients

The Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R) predicts increased risk of opioid misuse in chronic pain patients. We evaluated whether higher SOAPP-R scores are associated with greater opioid reinforcing properties, potentially contributing to their predictive utility. Across 2 counterbalanced laboratory sessions, 55 chronic low back pain sufferers completed the SOAPP-R at baseline and measures of back pain intensity, evoked pain responsiveness (thermal, ischemic), and subjective opioid effects after receiving intravenous morphine (.08 mg/kg) or saline placebo. Morphine effect measures were derived for all outcomes, reflecting the difference between morphine and placebo condition values. Higher SOAPP-R scores were significantly associated with greater desire to take morphine again, less feeling down and feeling bad, and greater reductions in sensory low back pain intensity following morphine administration. This latter effect was due primarily to SOAPP-R content assessing medication-specific attitudes and behavior. Individuals exceeding the clinical cutoff (18 or higher) on the SOAPP-R exhibited significantly greater morphine liking, desire to take morphine again, and feeling sedated; less feeling bad; and greater reductions in sensory low back pain following morphine. The SOAPP-R may predict elevated opioid risk in part by tapping into individual differences in opioid reinforcing effects.

PERSPECTIVE

Based on placebo-controlled morphine responses, associations were observed between higher scores on a common opioid risk screener (SOAPP-R) and greater desire to take morphine again, fewer negative subjective morphine effects, and greater analgesia. Opioids may provide the best analgesia in those patients at greatest risk of opioid misuse.

Review of the Performance of Quantitative Sensory Testing Methods to Detect Hyperalgesia in Chronic Pain Patients on Long-term Opioids

Background:

Opioid-induced hyperalgesia is a clinical syndrome whereby patients on long-term opioids become more sensitive to pain while taking opioids. Opioid-induced hyperalgesia is characterized by increased pain intensity over time, spreading of pain to other locations, and increased pain sensation to external stimuli. To characterize opioid-induced hyperalgesia, laboratory methods to measure hyperalgesia have been developed. To determine the performance of these methods, the authors conducted a systematic review of clinical studies that incorporate measures of hyperalgesia in chronic pain patients on long-term opioids.

Methods:

PubMed and Cochrane databases were searched (terms: opioid induced hyperalgesia, study or trial, and long-term or chronic). Studies published in English were selected if they were conducted in chronic pain patients on long-term opioids and incorporated measures of hyperalgesia; acute/single-dose studies and/or conducted in healthy volunteers were excluded.

Results:

Fourteen articles made the final selection (11 were selected from the search and 3 others were found from additional sources); there was one randomized controlled trial, one prospective controlled study, three prospective uncontrolled studies, and nine cross-sectional observation studies. Hyperalgesia measurement paradigms used included cold pain, heat pain, pressure pain, electrical pain, ischemic pain, and injection pain. Although none of the stimuli were capable of detecting patients’ hyperalgesia, heat pain sensitivity showed some promising results.

Conclusions:

None of the measures reviewed herein met the criteria of a definitive standard for the measurement of hyperalgesia. Additional studies that use improved study design should be conducted.

Effects of testosterone replacement in men with opioid-induced androgen deficiency: a randomized controlled trial

Symptomatic androgen deficiency is common in patients taking opioid analgesics, as these drugs potently suppress the hypothalamic-pituitary-gonadal axis. However, the efficacy of testosterone replacement in this setting remains unclear. The objective of this trial was to evaluate the efficacy of testosterone replacement on pain perception and other androgen-dependent outcomes in men with opioid-induced androgen deficiency. We conducted a randomized, double-blind, parallel placebo-controlled trial at an outpatient academic research center. Participants were men aged 18 to 64 years on opioid analgesics for chronic noncancer pain, and total testosterone levels were <350 ng/dL. Participants were randomly assigned to 14 weeks of daily transdermal gel that contained 5 g of testosterone or placebo. Primary outcomes were changes in self-reported clinical pain and objectively assessed pain sensitivity. Sexual function, quality of life, and body composition were also assessed. The mean age was 49 years. The median total and free testosterone levels at baseline were 243 ng/dL and 47 pg/mL and 251 ng/dL and 43 pg/mL in the testosterone and placebo arm, respectively. Of the 84 randomized participants, 65 had follow-up data on efficacy outcomes. Compared with men assigned to the placebo arm, those assigned to testosterone replacement experienced greater improvements in pressure and mechanical hyperalgesia, sexual desire, and role limitation due to emotional problems. Testosterone administration was also associated with an improvement in body composition. There were no between-group differences in changes in self-reported pain. In conclusion, in men with opioid-induced androgen deficiency, testosterone administration improved pain sensitivity, sexual desire, body composition, and aspects of quality of life.

Prescription drug abuse: from epidemiology to public policy

Prescription drug abuse has reached an epidemic level in the United States. The prevalence of prescription drug abuse escalated rapidly beginning in the late 1990s, requiring a significant increase in research to better understand the nature and treatment of this problem. Since this time, a research literature has begun to develop and has provided important information about how prescription drug abuse is similar to, and different from the abuse of other substances. This introduction to a special issue of the Journal of Substance Abuse Treatment on prescription drug abuse provides an overview of the current status of the research literature in this area. The papers in this special issue include a sampling of the latest research on the epidemiology, clinical correlates, treatment, and public policy considerations of prescription drug abuse. Although much has been learned about prescription drug abuse in recent years, this research remains in early stages, particularly with respect to understanding effective treatments for this population. Future research priorities include studies on the interaction of prescription drugs with other licit and illicit substances, the impact of prescription drug abuse across the lifespan, the optimal treatment for prescription drug abuse and co-occurring conditions, and effective public policy initiatives for reducing prescription drug abuse.

Distraction Analgesia in Chronic Pain Patients

Background:

Diverting attention away from noxious stimulation (i.e., distraction) is a common pain-coping strategy. Its effects are variable across individuals, however, and the authors hypothesized that chronic pain patients who reported higher levels of pain catastrophizing would derive less pain-reducing benefit from distraction.

Methods:

Chronic pain patients (n = 149) underwent psychometric and quantitative sensory testing, including assessment of the temporal summation of pain in the presence and absence of a distracting motor task.

Results:

A simple distraction task decreased temporal summation of pain overall, but, surprisingly, a greater distraction analgesia was observed in high catastrophizers. This enhanced distraction analgesia in high catastrophizers was not altered when controlling for current pain scores, depression, anxiety, or opioid use (analysis of covariance [ANCOVA]: F = 8.7, P &lt; 0.005). Interestingly, the magnitude of distraction analgesia was inversely correlated with conditioned pain modulation (Pearson R = −0.23, P = 0.005).

Conclusion:

Distraction produced greater analgesia among chronic pain patients with higher catastrophizing, suggesting that catastrophizing’s pain-amplifying effects may be due in part to greater attention to pain, and these patients may benefit from distraction-based pain management approaches. Furthermore, these data suggest that distraction analgesia and conditioned pain modulation may involve separate underlying mechanisms.

Increased pain sensitivity in chronic pain subjects on opioid therapy: a cross-sectional study using quantitative sensory testing

OBJECTIVE

The aim of this study was to compare the sensitivity to experimental pain of chronic pain patients on opioid therapy vs chronic pain patients on non-opioid therapy and healthy subjects by quantitative sensory testing (QST).

SETTING

There is a growing body of evidence demonstrating that chronic use of opioid drugs may alter pain sensitivity. Identifying the characteristic changes in thermal pain sensitivity in chronic opioid users will be helpful in diagnosing pain sensitivity alterations associated with chronic opioid use.

METHODS

Utilizing an office-based QST technique, we examined thermal pain threshold, tolerance, and temporal summation in 172 chronic pain subjects receiving opioid therapy, 121 chronic pain subjects receiving non-opioid therapy, and 129 healthy subjects.

RESULTS

In chronic pain subjects receiving opioid therapy, there were detectable differences in QST characteristics compared with both chronic pain subjects receiving non-opioid therapy and healthy subjects. Specifically, in chronic pain subjects receiving opioid therapy, 1) sensitivity to heat pain was increased; threshold to heat pain was significantly lower; 2) tolerance to supra-threshold heat pain was significantly decreased; and 3) temporal pain summation was exacerbated, as compared with chronic pain subjects receiving non-opioid therapy. In a subgroup of chronic pain subjects receiving opioid therapy with increased heat pain sensitivity, their average opioid medication dosage was significantly higher than those who had an above-average heat pain threshold. Moreover, a subset of chronic pain subjects on opioid therapy exhibited a significant decrease in diffuse noxious inhibitory control (DNIC) compared with chronic pain subjects on non-opioid therapy.

CONCLUSION

These findings suggest that a subset of QST parameters can reflect opioid-associated thermal pain sensitivity alteration, including decreased heat pain threshold, decreased cold and heat pain tolerance, diminished DNIC, and/or exacerbated temporal summation.

Characteristics of chronic pain patients who take opioids and persistently report high pain intensity

BACKGROUND AND OBJECTIVES

The use of self-report questionnaires to detect characteristics of altered central pain processing, as seen in centralized pain disorders such as fibromyalgia, allow for the epidemiological studies of pain patients. Here, we assessed the relationship between reporting high levels of pain while taking opioids and the presence of characteristics associated with centralized pain.

METHODS

We evaluated 582 patients taking opioid medications using validated measures of clinical pain, neuropathic pain symptoms, mood, and functioning. A multivariate linear regression model was used to assess the association between levels of pain while taking opioids and presenting with characteristics consistent with having centralized pain.

RESULTS

We found that 49% of patients taking opioids continued to report severe pain (≥ 7/10). In multivariate analysis, factors associated with having higher levels of pain in opioid users included higher fibromyalgia survey scores (P = 0.001), more neuropathic pain symptoms (P < 0.001), and higher levels of depression (P = 0.002). Although only 3.2% were given a primary diagnosis of fibromyalgia by their physician, 40.8% met American College of Rheumatology survey criteria for fibromyalgia.

CONCLUSIONS

Our findings suggest that patients with persistently high pain scores despite opioid therapy are more likely than those with lower levels of pain to present with characteristics associated with having centralized pain. This study cannot determine whether these characteristics were present before (fibromyalgia-like patient) or after the initiation of opioids (opioid-induced hyperalgesia). Regardless, patients with a centralized pain phenotype are thought to be less responsive to opioids and may merit alternative approaches.

The association between catastrophizing and craving in patients with chronic pain prescribed opioid therapy: a preliminary analysis

BACKGROUND

A growing number of studies have shown that opioid craving (i.e., the perceived need or desire to consume opioids) is one of the strongest determinants of prescription opioid misuse in patients with chronic pain prescribed opioid therapy. To date, however, the factors that are associated with craving in patients with pain remain largely unexplored. Based on previous research, there is reason to believe that catastrophizing might be associated with heightened opioid craving.

OBJECTIVES

To test the hypothesis that catastrophizing would be associated with heightened craving in patients with chronic pain prescribed long-term opioid therapy.

DESIGN AND SUBJECTS, AND METHODS

In this cross-sectional study, 109 patients with chronic pain were asked to provide self-reports of catastrophizing and craving. Patients also provided self-reports of pain intensity and depressive symptoms.

RESULTS

We found that higher levels of catastrophizing were associated with higher levels of craving. Importantly, results of a regression analysis revealed that the association between catastrophizing and craving remained significant even after controlling for a host of demographic (i.e., age, sex), psychological (i.e., depressive symptoms), medical (i.e., pain intensity, pain duration), and medication regimen (i.e., opioid doses) variables.

CONCLUSIONS

Our preliminary findings provide valuable new insights into the determinants of craving in patients with pain. The finding that catastrophizing was associated with craving even after controlling for a host of demographic, psychological, medical, and medication regimen variables is particularly striking, and raises questions concerning the factors that underlie the association between catastrophizing and craving in patients prescribed opioid therapy.

Prescription opioid misuse among ED patients discharged with opioids

STUDY OBJECTIVES

The purposes of this study were to determine the prevalence of prescription opioid misuse in a cohort of discharged emergency department (ED) patients who received prescription opioids and to examine factors predictive of misuse.

METHODS

This prospective observational study enrolled a sample of ED patients aged 18 to 55 years who were discharged with a prescription opioid. Participants completed surveys at baseline in the ED, then 3 and 30 days later. Follow-up surveys contained questions about opioid use and misuse, including screening questions from the National Epidemiologic Survey on Alcohol and Related Conditions. Patients were categorized as misusers if they (1) self-escalated their dose, (2) obtained additional prescription opioids without a prescription, or (3) used for a reason besides pain.

RESULTS

Of the 85 patients who completed follow-ups, 36 (42%) reported misuse at either 3 or 30 days. There was no difference in demographic variables, pain scores, analgesic treatment, or discharge diagnoses between misusers and nonmisusers. Self-escalation of dose was the most common category of misuse (33/36; 92%). Taking prescription opioids without a doctor's prescription was reported by 39% (14/36), and taking pain medications for a reason other than pain was reported by 36% (13/36). The presence of disability, chronic pain, preexisting prescription opioid use, oxycodone use, and past 12-month risk of substance abuse were associated with misuse.

CONCLUSIONS

Prescription opioid misuse was prevalent among this cohort of ED patients. A heterogeneous mixture of behaviors was captured. Future research should focus on the etiologies of misuse with directed screening and interventions to decrease misuse.

Catastrophic thinking and increased risk for prescription opioid misuse in patients with chronic pain

BACKGROUND

As a consequence of the substantial rise in the prescription of opioids for the treatment of chronic noncancer pain, greater attention has been paid to the factors that may be associated with an increased risk for prescription opioid misuse. Recently, a growing number of studies have shown that patients with high levels of catastrophizing are at increased risk for prescription opioid misuse.

OBJECTIVE

The primary objective of this study was to examine the variables that might underlie the association between catastrophizing and risk for prescription opioid misuse in patients with chronic pain.

METHODS

Patients with chronic musculoskeletal pain (n=115) were asked to complete the SOAPP-R, a validated self-report questionnaire designed to identify patients at risk for prescription opioid misuse. Patients were also asked to complete self-report measures of pain intensity, catastrophizing, anxiety, and depression.

RESULTS

Consistent with previous research, we found that catastrophizing was associated with an increased risk for prescription opioid misuse. Results also revealed that the association between catastrophizing and risk for opioid misuse was partially mediated by patients' levels of anxiety. Follow-up analyses, however, indicated that catastrophizing remained a significant 'unique' predictor of risk for opioid misuse even when controlling for patients' levels of pain severity, anxiety and depressive symptoms.

DISCUSSION

Discussion addresses the factors that might place patients with high levels of catastrophizing at increased risk for prescription opioid misuse. The implications of our findings for the management of patients considered for opioid therapy are also discussed.

The downward spiral of chronic pain, prescription opioid misuse, and addiction: cognitive, affective, and neuropsychopharmacologic pathways

Prescription opioid misuse and addiction among chronic pain patients are emerging public health concerns of considerable significance. Estimates suggest that more than 10% of chronic pain patients misuse opioid analgesics, and the number of fatalities related to nonmedical or inappropriate use of prescription opioids is climbing. Because the prevalence and adverse consequences of this threat are increasing, there is a pressing need for research that identifies the biobehavioral risk chain linking chronic pain, opioid analgesia, and addictive behaviors. To that end, the current manuscript draws upon current neuropsychopharmacologic research to provide a conceptual framework of the downward spiral leading to prescription opioid misuse and addiction among chronic pain patients receiving opioid analgesic pharmacotherapy. Addictive use of opioids is described as the outcome of a cycle initiated by chronic pain and negative affect and reinforced by opioidergic-dopamingeric interactions, leading to attentional hypervigilance for pain and drug cues, dysfunctional connectivity between self-referential and cognitive control networks in the brain, and allostatic dysregulation of stress and reward circuitry. Implications for clinical practice are discussed; multimodal, mindfulness-oriented treatment is introduced as a potentially effective approach to disrupting the downward spiral and facilitating recovery from chronic pain and opioid addiction.

Long-term opioid treatment of chronic nonmalignant pain: unproven efficacy and neglected safety?

BACKGROUND

For the past 30 years, opioids have been used to treat chronic nonmalignant pain. This study tests the following hypotheses: (1) there is no strong evidence-based foundation for the conclusion that long-term opioid treatment of chronic nonmalignant pain is effective; and (2) the main problem associated with the safety of such treatment - assessment of the risk of addiction - has been neglected.

METHODS

Scientometric analysis of the articles representing clinical research in this area was performed to assess (1) the quality of presented evidence (type of study); and (2) the duration of the treatment phase. The sufficiency of representation of addiction was assessed by counting the number of articles that represent (1) editorials; (2) articles in the top specialty journals; and (3) articles with titles clearly indicating that the addiction-related safety is involved (topic-in-title articles).

RESULTS

Not a single randomized controlled trial with opioid treatment lasting >3 months was found. All studies with a duration of opioid treatment ≥6 months (n = 16) were conducted without a proper control group. Such studies cannot provide the consistent good-quality evidence necessary for a strong clinical recommendation. There were profound differences in the number of addiction articles related specifically to chronic nonmalignant pain patients and to opioid addiction in general. An inadequate number of chronic pain-related publications were observed with all three types of counted articles: editorials, articles in the top specialty journals, and topic-in-title articles.

CONCLUSION

There is no strong evidence-based foundation for the conclusion that long-term opioid treatment of chronic nonmalignant pain is effective. The above identified signs indicating neglect of addiction associated with the opioid treatment of chronic nonmalignant pain were present.

Alteration in pain modulation in women with persistent pain after lumpectomy: influence of catastrophizing

CONTEXT

Persistent pain is common after surgical treatment of breast cancer, but fairly little is known about the changes in sensory processing that accompany such pain syndromes.

OBJECTIVES

This study used quantitative sensory testing to compare psychophysical responses to standardized noxious stimulation in two groups of women who had previously undergone breast cancer surgery: women with (n=37) and without (n=34) persistent postoperative pain.

METHODS

Participants underwent a single testing session in which responses to a variety of noxious stimuli were assessed.

RESULTS

Findings suggested that women with chronic pain after breast cancer surgery display enhanced temporal summation of mechanical pain, deficits in endogenous pain inhibition, and more intense painful aftersensations compared with those without long-term pain. Some of these group differences were mediated by higher levels of pain catastrophizing in the group of women with persistent pain.

CONCLUSION

These findings suggest that persistent postoperative pain is associated with alterations in central nervous system pain-modulatory processes. Future treatment studies might benefit from targeting these pain-modulatory systems, and additional studies using functional neuroimaging methods might provide further valuable information about the pathophysiology of long-term postsurgical pain in women treated for breast cancer.

Endogenous opioid function mediates the association between laboratory-evoked pain sensitivity and morphine analgesic responses

Predictors of responsiveness to opioid analgesic medications are not well understood. This study tested whether individual differences in endogenous opioid (EO) function are associated with analgesic responsiveness to morphine. In randomized, counterbalanced order over 3 sessions, 45 chronic low back pain participants and 31 healthy controls received an opioid antagonist (8 mg naloxone), morphine (0.08 mg/kg), or placebo. Participants then engaged in 2 laboratory-evoked pain tasks (ischemic and thermal). Outcomes included pain threshold, pain tolerance, and pain ratings. Indexes of EO function and morphine analgesic responsiveness were derived for each measure as the difference in pain responses between the placebo condition and naloxone or morphine condition, respectively. For all 7 pain measures across the 2 laboratory pain tasks, greater EO function was associated with significantly lower morphine analgesic responsiveness (P<0.001-P=0.02). Morphine reduced pain responses of low EO individuals to levels similar to those of high EO individuals receiving placebo. Higher placebo condition-evoked pain sensitivity was associated with significantly greater morphine analgesic responsiveness for 5 of 7 pain measures (P<0.001-P=0.02). These latter associations were significantly mediated by EO function for 4 of these 5 pain outcomes (all P values<0.05). In the laboratory-evoked pain context, opioid analgesic medications may supplement inadequate EO analgesia, with little incremental benefit in those with preexisting high EO function. Implications for personalized medicine are discussed.

Persistent pain in postmastectomy patients: comparison of psychophysical, medical, surgical, and psychosocial characteristics between patients with and without pain

Persistent postmastectomy pain (PPMP) is a major individual and public health problem. Increasingly, psychosocial factors such as anxiety and catastrophizing are being revealed as crucial contributors to individual differences in pain processing and outcomes. Furthermore, differences in patients' responses to standardized quantitative sensory testing (QST) may aid in the discernment of who is at risk for acute and chronic pain after surgery. However, characterization of the variables that differentiate those with PPMP from those whose acute postoperative pain resolves is currently incomplete. The purpose of this study was to investigate important surgical, treatment-related, demographic, psychophysical, and psychosocial factors associated with PPMP by comparing PPMP cases with PPMP-free controls. Pain was assessed using the breast cancer pain questionnaire to determine the presence and extent of PPMP. Psychosocial and demographic information were gathered via phone interview, and women underwent a QST session. Consistent with most prior research, surgical and disease-related variables did not differ significantly between cases and controls. Furthermore, treatment with radiation, chemotherapy, or hormone therapy was also not more common among those with PPMP. In contrast, women with PPMP did show elevated levels of distress-related psychosocial factors such as anxiety, depression, catastrophizing, and somatization. Finally, QST in nonsurgical body areas revealed increased sensitivity to mechanical stimulation among PPMP cases, while thermal pain responses were not different between the groups. These findings suggest that an individual's psychophysical and psychosocial profile may be more strongly related to PPMP than their surgical treatment.

Subgroups based on thermal and pressure pain thresholds in women with chronic whiplash display differences in clinical presentation - an explorative study

PURPOSE

To investigate the presence of subgroups in chronic whiplash-associated disorders (WAD) based on pain thresholds for pressure (PPT), cold (CPT), and heat (HPT) and to compare these subgroups with respect to symptomatology, disability, and health aspects.

METHODS

Two groups of female subjects - patients with chronic WAD (n = 28) and healthy controls (CON; n = 29) - were investigated. Quantitative sensory testing (QST) for thermal thresholds and algometry for PPT at four sites in the body (over the trapezius and tibialis anterior bilaterally) were determined. Habitual pain intensities, psychological strain, disability, and health aspects were registered using a questionnaire.

RESULTS

A CLUSTER ANALYSIS BASED ON PPT, CPT, AND HPT IDENTIFIED TWO SUBGROUPS OF CHRONIC WAD: one sensitive subgroup (s-WAD; n = 21), and one less sensitive subgroup (ls-WAD; n = 6). S-WAD displayed widespread hyperalgesia, whereas ls-WAD had localized hyperalgesia in the neck area, with tendencies to supernormal values in remote areas of the body. Generally, s-WAD had a significantly worse situation than the CON with respect to symptomatology, disability, and health aspects. The ls-WAD group was intermediary between s-WAD and CON in these aspects.

CONCLUSION

Different explanations, eg, severity of the pain condition per se, etiological factors, and pre-trauma differences in pain sensitivity, may exist for the differences in pain thresholds between the two subgroups. Future research should investigate the role of pain thresholds in the chronic stage to determine the efficacy of treatment interventions.

Risk factor assessment for problematic use of opioids for chronic pain

Opioid analgesics provide effective treatment for noncancer pain, but many health providers have concerns about cognitive effects, tolerance, dependence, and addiction. Misuse of opioids is prominent in patients with chronic pain and early recognition of misuse risk could help providers offer adequate patient care while implementing appropriate levels of monitoring to reduce aberrant drug-related behaviors. Many persons with chronic pain also have significant medical and psychiatric comorbidities that affect treatment decisions. Neuropsychologists can play an important role in the identification of psychological and social dysfunction and in matching personal characteristics to effective interventions as part of a multidisciplinary approach to pain management. The assessment of different domains using semi-structured interviews, sensory and neuropsychological testing, and standardized self-report measures permits identification of somatosensory, emotional, cognitive, behavioral, and social issues in order to facilitate treatment planning. In this review we discuss opioid abuse and misuse issues that often arise in the treatment of patients with chronic pain, and present an overview of assessment and treatment strategies that can be effective in improving outcomes associated with the use of prescription opioids for pain. Finally we briefly discuss the effect of opiate analgesics on cognition and review some intervention strategies for chronic pain patients.

Evoked pain analgesia in chronic pelvic pain patients using respiratory-gated auricular vagal afferent nerve stimulation

OBJECTIVE

Previous vagus nerve stimulation (VNS) studies have demonstrated antinociceptive effects, and recent noninvasive approaches, termed transcutaneous-vagus nerve stimulation (t-VNS), have utilized stimulation of the auricular branch of the vagus nerve in the ear. The dorsal medullary vagal system operates in tune with respiration, and we propose that supplying vagal afferent stimulation gated to the exhalation phase of respiration can optimize t-VNS.

DESIGN

Counterbalanced, crossover study.

PATIENTS

Patients with chronic pelvic pain (CPP) due to endometriosis in a specialty pain clinic. INTERVENTIONS/OUTCOMES: We evaluated evoked pain analgesia for respiratory-gated auricular vagal afferent nerve stimulation (RAVANS) compared with nonvagal auricular stimulation (NVAS). RAVANS and NVAS were evaluated in separate sessions spaced at least 1 week apart. Outcome measures included deep-tissue pain intensity, temporal summation of pain, and anxiety ratings, which were assessed at baseline, during active stimulation, immediately following stimulation, and 15 minutes after stimulus cessation.

RESULTS

RAVANS demonstrated a trend for reduced evoked pain intensity and temporal summation of mechanical pain, and significantly reduced anxiety in N = 15 CPP patients, compared with NVAS, with moderate to large effect sizes (η(2) > 0.2).

CONCLUSION

Chronic pain disorders such as CPP are in great need of effective, nonpharmacological options for treatment. RAVANS produced promising antinociceptive effects for quantitative sensory testing (QST) outcomes reflective of the noted hyperalgesia and central sensitization in this patient population. Future studies should evaluate longer-term application of RAVANS to examine its effects on both QST outcomes and clinical pain.