AAAPT Diagnostic Criteria for Acute Neuropathic Pain

OBJECTIVE

Acute neuropathic pain is a significant diagnostic challenge, and it is closely related to our understanding of both acute pain and neuropathic pain. Diagnostic criteria for acute neuropathic pain should reflect our mechanistic understanding and provide a framework for research on and treatment of these complex pain conditions.

METHODS

The Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership with the U.S. Food and Drug Administration (FDA), the American Pain Society (APS), and the American Academy of Pain Medicine (AAPM) collaborated to develop the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) for acute pain. A working group of experts in research and clinical management of neuropathic pain was convened. Group members used literature review and expert opinion to develop diagnostic criteria for acute neuropathic pain, as well as three specific examples of acute neuropathic pain conditions, using the five dimensions of the AAAPT classification of acute pain.

RESULTS

AAAPT diagnostic criteria for acute neuropathic pain are presented. Application of these criteria to three specific conditions (pain related to herpes zoster, chemotherapy, and limb amputation) illustrates the spectrum of acute neuropathic pain and highlights unique features of each condition.

CONCLUSIONS

The proposed AAAPT diagnostic criteria for acute neuropathic pain can be applied to various acute neuropathic pain conditions. Both the general and condition-specific criteria may guide future research, assessment, and management of acute neuropathic pain.

Is Buprenorphine Effective for Chronic Pain? A Systematic Review and Meta-analysis

OBJECTIVE

The objective was to perform a systematic review and meta-analysis of the literature on the effects of buprenorphine on chronic pain outcomes (i.e., patient-reported pain intensity) in patients with and without opioid use disorder (OUD).

DESIGN

Ovid/Medline, PubMed, Embase, and the Cochrane Library were searched for studies that explored the effectiveness (in reducing pain) of buprenorphine treatment for chronic pain patients with and without a history of OUD. Randomized controlled trials and observational studies were included in the review.

METHODS

Two separate searches were conducted to identify buprenorphine trials that included chronic pain patients either with or without OUD. Five studies used validated pain report measures and included a chronic pain population with OUD. Nine studies used validated report measures and included chronic pain patients without OUD. Meta-analysis was performed using the R, version 3.2.2, Metafor package, version 1.9-7.

RESULTS

The meta-analysis revealed that buprenorphine has a beneficial effect on pain intensity overall, with a small mean effect size in patients with comorbid chronic pain and OUD and a moderate- to large-sized effect in chronic pain patients without OUD.

CONCLUSIONS

Our results indicate that buprenorphine is modestly beneficial in reducing pain intensity in patients without OUD. Although informative, these findings should be carefully interpreted due to the small amount of data available and the variation in study designs.

Brief Self-Compassion Training Alters Neural Responses to Evoked Pain for Chronic Low Back Pain: A Pilot Study

OBJECTIVE

Self-compassion meditation, which involves compassion toward the self in moments of suffering, shows promise for improving pain-related functioning, but its underlying mechanisms are unknown. This longitudinal, exploratory pilot study investigated the effects of a brief (eight contact hours, two weeks of home practice) self-compassion training on pain-related brain processing in chronic low back pain (cLBP).

METHODS

We evaluated functional magnetic resonance imaging (fMRI) response to evoked pressure pain and its anticipation during a self-compassionate state and compared altered brain responses following training with changes on self-reported measures of self-compassion (Self-Compassion Scale [SCS]), interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness [MAIA]), and clinical pain intensity.

RESULTS

In a sample of participants with cLBP (N = 20 total, N = 14 with complete longitudinal data) who underwent self-compassion training, we observed reduced clinical pain intensity and disability (P < 0.01) and increased trait self-compassion and interoceptive awareness (all P < 0.05) following training. Evoked pressure pain response in the right temporo-parietal junction (TPJ) was reduced following training, and decreases were associated with reduced clinical pain intensity. Further, increased fMRI responses to pain anticipation were observed in the right dorsolateral prefrontal cortex (dlPFC) and ventral posterior cingulate cortex (vPCC), and these increases were associated with mean post-training changes in SCS scores and scores from the body listening subscale of the MAIA.

DISCUSSION

These findings, though exploratory and lacking comparison with a control condition, suggest that self-compassion training supports regulation of pain through the involvement of self-referential (vPCC), salience-processing (TPJ), and emotion regulatory (dlPFC) brain areas. The results also suggest that self-compassion could be an important target in the psychotherapeutic treatment of cLBP, although further studies using controlled experimental designs are needed to determine the specificity of these effects.

A picture is worth a thousand words: linking fibromyalgia pain widespreadness from digital pain drawings with pain catastrophizing and brain cross-network connectivity

ABSTRACT

Pain catastrophizing is prominent in chronic pain conditions such as fibromyalgia and has been proposed to contribute to the development of pain widespreadness. However, the brain mechanisms responsible for this association are unknown. We hypothesized that increased resting salience network (SLN) connectivity to nodes of the default mode network (DMN), representing previously reported pain-linked cross-network enmeshment, would be associated with increased pain catastrophizing and widespreadness across body sites. We applied functional magnetic resonance imaging (fMRI) and digital pain drawings (free-hand drawing over a body outline, analyzed using conventional software for multivoxel fMRI analysis) to investigate precisely quantified measures of pain widespreadness and the associations between pain catastrophizing (Pain Catastrophizing Scale), resting brain network connectivity (Dual-regression Independent Component Analysis, 6-minute multiband accelerated fMRI), and pain widespreadness in fibromyalgia patients (N = 79). Fibromyalgia patients reported pain in multiple body areas (most frequently the spinal region, from the lower back to the neck), with moderately high pain widespreadness (mean ± SD: 26.1 ± 24.1% of total body area), and high pain catastrophizing scale scores (27.0 ± 21.9, scale range: 0-52), which were positively correlated (r = 0.26, P = 0.02). A whole-brain regression analysis focused on SLN connectivity indicated that pain widespreadness was also positively associated with SLN connectivity to the posterior cingulate cortex, a key node of the DMN. Moreover, we found that SLN-posterior cingulate cortex connectivity statistically mediated the association between pain catastrophizing and pain widespreadness (P = 0.01). In conclusion, we identified a putative brain mechanism underpinning the association between greater pain catastrophizing and a larger spatial extent of body pain in fibromyalgia, implicating a role for brain SLN-DMN cross-network enmeshment in mediating this association.

The neuroinflammatory component of negative affect in patients with chronic pain

Negative affect (NA) is a significant cause of disability for chronic pain patients. While little is known about the mechanism underlying pain-comorbid NA, previous studies have implicated neuroinflammation in the pathophysiology of both depression and chronic pain. Here, we tested the hypothesis that NA in pain patients is linked to elevations in the brain levels of the glial marker 18 kDa translocator protein (TSPO), and changes in functional connectivity. 25 cLBP patients (42.4 ± 13 years old; 13F, 12M) with chronic low back pain (cLBP) and 27 healthy control subjects (48.9 ± 13 years old; 14F, 13M) received an integrated (i.e., simultaneous) positron emission tomography (PET)/magnetic resonance imaging (MRI) brain scan with the second-generation TSPO ligand [¹¹C]PBR28. The relationship between [¹¹C]PBR28 signal and NA was assessed first with regression analyses against Beck Depression Inventory (BDI) scores in patients, and then by comparing cLBP patients with little-to-no, or mild-to-moderate depression against healthy controls. Further, the relationship between PET signal, BDI and frontolimbic functional connectivity was evaluated in patients with mediation models. PET signal was positively associated with BDI scores in patients, and significantly elevated in patients with mild-to-moderate (but not low) depression compared with controls, in anterior middle and pregenual anterior cingulate cortices (aMCC, pgACC). In the pgACC, PET signal was also associated with this region's functional connectivity to the dorsolateral PFC (pgACC-dlPFC), and mediated of the association between pgACC-dlPFC connectivity and BDI. These observations support a role for glial activation in pain-comorbid NA, identifying in neuroinflammation a potential therapeutic target for this condition.

Modifiable Psychological Factors Affecting Functioning in Fibromyalgia

Objective: To examine the role of several interrelated, potentially modifiable psychological factors (i.e., mindfulness and catastrophizing) in influencing patient-reported functioning. Methods: In this cross-sectional study, 107 patients with fibromyalgia completed self-report assessments of pain severity, functioning and impact of symptoms, mindfulness, and pain catastrophizing. Linear regression and bootstrapping mediation analyses were performed to assess the relationships between these factors. Results: Pain intensity was significantly and positively associated with pain catastrophizing and impact of fibromyalgia on functioning. Linear regression analyses indicated that pain intensity, catastrophizing, and mindfulness affect functioning in fibromyalgia. Follow-up mediation analysis revealed a significant indirect effect of pain catastrophizing on the relationship between pain intensity and fibromyalgia functioning. Conclusion: Individuals with fibromyalgia who have higher levels of pain and catastrophizing, and lower levels of mindfulness, are more likely to experience impaired functioning. Our findings suggest that pain catastrophizing appears to be an especially important variable contributing to reduced functioning in women with fibromyalgia. Therefore, catastrophizing-reducing treatments (e.g., cognitive behavioral therapy) are likely to have direct, beneficial impacts on functioning.

Disparities in Acute Pain Treatment by Cognitive Status in Older Adults With Hip Fracture

BACKGROUND

We examined the disparities in emergency department (ED) pain treatment based on cognitive status in older adults with an acute hip fracture.

METHODS

Observational study in an academic ED in the Bronx, New York. One hundred forty-four adults aged 65 years and older with acute hip fracture were administered the Telephone Interview for Cognitive Status (TICS) while in the ED. The primary outcome was receipt of any parenteral analgesic. The risk factor of interest was cognitive impairment (TICS ≤ 25). Secondary outcomes included receipt of any opioid, receipt of any analgesic, total dose of analgesics in intravenous morphine equivalent units (MEQ), and time to receiving first analgesic.

RESULTS

Of the 87 (60%) study patients who were cognitively impaired, 60% received a parenteral analgesic compared to 79% of the 57 cognitively unimpaired patients (RR 0.76 [95% CI 0.61, 0.94]). The effect of cognitive impairment on receiving any opioids (RR: 0.81, 95% CI 0.67, 0.98) and any analgesic (RR: 0.85; 95% CI: 0.71, 1.01) was similar. The median analgesic dose in cognitively impaired patients was significantly lower than in cognitively unimpaired patients (4 MEQ vs 8 MEQ, p = .003).

CONCLUSION

Among older adults presenting to the ED with acute hip fracture, cognitive impairment was independently associated with lower likelihood of receiving analgesia and lower amount of opioid analgesia.

Cross-sectional study of psychosocial and pain-related variables among patients with chronic pain during a time of social distancing imposed by the coronavirus disease 2019 pandemic

ABSTRACT

The COVID-19 pandemic has had a tremendous impact, including on individuals with chronic pain. The social distancing policies necessary to slow the spread of SARS-CoV-2 have involved increased levels of social isolation. This cross-sectional survey study examined pain severity and interference among individuals with chronic pain during an early phase of social distancing mandates and identified characteristics of individuals who were most impacted. Approximately 4 to 8 weeks after social distancing mandates commenced in the state of Massachusetts, 150 patients with fibromyalgia, chronic spine, and postsurgical pain completed demographic, pain, social distancing, and validated psychosocial questionnaires. Patients self-reported an overall significant increase in pain severity and pain interference, compared with before social distancing, although both pain severity and interference were quite variable among individuals under conditions of social distancing. Several demographic, socioeconomic, and psychosocial factors were associated with greater pain severity and interference during social distancing. Multivariable linear regression demonstrated that female sex, nonwhite race, lower education, disability, fibromyalgia, and higher pain catastrophizing were independently associated with greater pain severity, while female sex and pain catastrophizing were independently associated greater pain interference. The findings suggest that individual differences among patients with chronic pain should be considered in the planning, development, and prioritization of interventions to improve pain care and to prevent worsening of symptoms during the continuing COVID-19 pandemic.

Brain Responses to Noxious Stimuli in Patients With Chronic Pain: A Systematic Review and Meta-analysis

IMPORTANCE

Functional neuroimaging is a valuable tool for understanding how patients with chronic pain respond to painful stimuli. However, past studies have reported heterogenous results, highlighting opportunities for a quantitative meta-analysis to integrate existing data and delineate consistent associations across studies.

OBJECTIVE

To identify differential brain responses to noxious stimuli in patients with chronic pain using functional magnetic resonance imaging (fMRI) while adhering to current best practices for neuroimaging meta-analyses.

DATA SOURCES

All fMRI experiments published from January 1, 1990, to May 28, 2019, were identified in a literature search of PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, PsycINFO, and SCOPUS.

STUDY SELECTION

Experiments comparing brain responses to noxious stimuli in fMRI between patients and controls were selected if they reported whole-brain results, included at least 10 patients and 10 healthy control participants, and used adequate statistical thresholding (voxel-height P < .001 or cluster-corrected P < .05). Two independent reviewers evaluated titles and abstracts returned by the search. In total, 3682 abstracts were screened, and 1129 full-text articles were evaluated.

DATA EXTRACTION AND SYNTHESIS

Thirty-seven experiments from 29 articles met inclusion criteria for meta-analysis. Coordinates reporting significant activation differences between patients with chronic pain and healthy controls were extracted. These data were meta-analyzed using activation likelihood estimation. Data were analyzed from December 2019 to February 2020.

MAIN OUTCOMES AND MEASURES

A whole-brain meta-analysis evaluated whether reported differences in brain activation in response to noxious stimuli between patients and healthy controls were spatially convergent. Follow-up analyses examined the directionality of any differences. Finally, an exploratory (nonpreregistered) region-of-interest analysis examined differences within the pain network.

RESULTS

The 37 experiments from 29 unique articles included a total of 511 patients and 433 controls (944 participants). Whole-brain meta-analyses did not reveal significant differences between patients and controls in brain responses to noxious stimuli at the preregistered statistical threshold. However, exploratory analyses restricted to the pain network revealed aberrant activity in patients.

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, preregistered, whole-brain analyses did not reveal aberrant fMRI activity in patients with chronic pain. Exploratory analyses suggested that subtle, spatially diffuse differences may exist within the pain network. Future work on chronic pain biomarkers may benefit from focus on this core set of pain-responsive areas.

Cost-effectiveness of duloxetine for knee OA subjects: the role of pain severity

OBJECTIVE

Establish the impact of pain severity on the cost-effectiveness of generic duloxetine for knee osteoarthritis (OA) in the United States.

DESIGN

We used a validated computer simulation of knee OA to compare usual care (UC) - intra-articular injections, opioids, and total knee replacement (TKR) - to UC preceded by duloxetine in those no longer achieving pain relief from non-steroidal anti-inflammatory drugs (NSAIDs). Outcomes included quality-adjusted life years (QALYs), lifetime medical costs, and incremental cost-effectiveness ratios (ICERs). We considered cohorts with mean ages 57-75 years and Western Ontario and McMaster Osteoarthritis Index (WOMAC) pain 25-55 (0-100, 100-worst). We derived inputs from published data. We discounted costs and benefits 3% annually. We conducted sensitivity analyses of duloxetine efficacy, duration of pain relief, toxicity, and costs.

RESULTS

Among younger subjects with severe pain (WOMAC pain = 55), duloxetine led to an additional 9.6 QALYs per 1,000 subjects (ICER = $88,500/QALY). The likelihood of duloxetine being cost-effective at willingness-to-pay (WTP) thresholds of $50,000/QALY and $100,000/QALY was 40% and 54%. Offering duloxetine to older patients with severe pain led to ICERs >$150,000/QALY. Offering duloxetine to subjects with moderate pain (pain = 25) led to ICERs <$50,000/QALY, regardless of age. Among knee OA subjects with severe pain (pain = 55) who are unwilling or unable to undergo TKR, ICERs were <$50,600/QALY, regardless of age.

CONCLUSIONS

Duloxetine is a cost-effective addition to knee OA UC for subjects with moderate pain or those with severe pain unable or unwilling to undergo TKR. Among younger subjects with severe pain, duloxetine is cost-effective at WTP thresholds >$88,500/QALY.

The Prevalence of Psychiatric and Chronic Pain Comorbidities in Fibromyalgia: an ACTTION systematic review

Fibromyalgia (FM) is a chronic widespread pain condition that overlaps with multiple comorbid health conditions and contributes to considerable patient distress. The aim of this review was to provide a systematic overview of psychiatric and chronic pain comorbidities among patients diagnosed with FM and to inform the development of recommendations for the design of clinical trials. Thirty-one, cross-sectional, clinical epidemiology studies that evaluated patients diagnosed with FM were included for review. None of the reviewed studies reported on the incidence of these comorbidities. Sample size-weighted prevalence estimates were calculated when prevalence data were reported in 2 or more studies for the same comorbid condition. The most prevalent comorbidity across all studies reviewed was depression/major depressive disorder (MDD) with over half of the patients included having this diagnosis in their lifetime (weighted prevalence up to 63%). In addition, nearly one-third of FM patients examined had current or lifetime bipolar disorder, panic disorder, or post-traumatic stress disorder. Less common psychiatric disorders reported included generalized anxiety disorder, obsessive compulsive disorder, and specific phobias (agoraphobia, social phobia). There were fewer studies that examined chronic pain comorbidities among FM patients, but when evaluated, prevalence was also high ranging from 39% to 76% (i.e., chronic tension-type or migraine headache, irritable bowel syndrome, myofascial pain syndrome, and temporomandibular disorders). The results of the review suggest that depression and chronic pain conditions involving head/jaw pain and IBS were elevated among FM patients compared to other conditions in the clinic-based studies. In contrast, anxiety-related disorders were much less common. Addressing the presence of these comorbid health conditions in clinical trials of treatments for FM would increase the generalizability and real-world applicability of FM research.

Increased Salience Network Connectivity Following Manual Therapy is Associated with Reduced Pain in Chronic Low Back Pain Patients

Chronic low back pain (cLBP) has been associated with changes in brain plasticity. Nonpharmacological therapies such as Manual Therapy (MT) have shown promise for relieving cLBP. However, translational neuroimaging research is needed to understand potential central mechanisms supporting MT. We investigated the effect of MT on resting-state salience network (SLN) connectivity, and whether this was associated with changes in clinical pain. Fifteen cLBP patients, and 16 matched healthy controls (HC) were scanned with resting functional Magnetic Resonance Imaging (fMRI), before and immediately after a MT intervention (cross-over design with two separate visits, pseudorandomized, grades V 'Manipulation' and III 'Mobilization' of the Maitland Joint Mobilization Grading Scale). Patients rated clinical pain (0-100) pre- and post-therapy. SLN connectivity was assessed using dual regression probabilistic independent component analysis. Both manipulation (Pre: 39.43 ± 16.5, Post: 28.43 ± 16.5) and mobilization (Pre: 38.83 ± 17.7, Post: 31.76 ± 19.4) reduced clinical back pain (P < .05). Manipulation (but not mobilization) significantly increased SLN connectivity to thalamus and primary motor cortex. Additionally, a voxelwise regression indicated that greater MT-induced increase in SLN connectivity to the lateral prefrontal cortex was associated with greater clinical back pain reduction immediately after intervention, for both manipulation (r = -0.8) and mobilization (r = -0.54). Our results suggest that MT is successful in reducing clinical low back pain by both spinal manipulation and spinal mobilization. Furthermore, this reduction post-manipulation occurs via modulation of SLN connectivity to sensorimotor, affective, and cognitive processing regions. PERSPECTIVE: MT both reduces clinical low back pain and modulates brain activity important for the processing of pain. This modulation was shown by increased functional brain connectivity between the salience network and brain regions involved in cognitive, affective, and sensorimotor processing of pain.

Does screening for depressive symptoms help optimize duloxetine use in knee OA patients with moderate pain? A cost-effectiveness analysis

OBJECTIVE

Duloxetine is an FDA-approved treatment for both osteoarthritis (OA) pain and depression, but uptake of duloxetine in knee OA management varies. We examined the cost-effectiveness of adding duloxetine to knee OA care with or without depression screening.

METHODS

We used the Osteoarthritis Policy Model, a validated computer microsimulation of knee OA, to examine the value of duloxetine for knee OA patients with moderate pain by comparing three strategies: 1) usual care (UC); 2) duloxetine for those who screen positive for depression on the Patient Health Questionnaire 9 (PHQ-9) + UC; and 3) universal duloxetine + UC. Outcomes included quality-adjusted life years (QALYs), lifetime direct medical costs, and incremental cost-effectiveness ratios (ICERs), discounted at 3% annually. Model inputs, drawn from published literature and national databases, included: annual cost of duloxetine, $721-$937; average pain reduction for duloxetine, 17.5 points on the WOMAC pain scale (0-100); likelihood of depression remission with duloxetine, 27.4%. We considered two willingness-to-pay (WTP) thresholds of $50,000/QALY and $100,000/QALY. We varied parameters related to the PHQ-9 and duloxetine's cost, efficacy, and toxicities to address uncertainty in model inputs.

RESULTS

The screening strategy led to an additional 17 QALYs per 1,000 subjects and increased costs by $289/subject (ICER=$17,000/QALY). Universal duloxetine led to an additional 31 QALYs per 1,000 subjects and $1,205/subject (ICER=$39,300/QALY). Under the majority of sensitivity analyses, universal duloxetine was cost-effective at the $100,000/QALY threshold.

CONCLUSION

Adding duloxetine to usual care for knee OA patients with moderate pain, regardless of depressive symptoms, is cost-effective at frequently-used WTP thresholds.

The Impact of Music on Nociceptive Processing

OBJECTIVE

Music has been shown to modulate pain, although the impact of music on specific aspects of nociceptive processing is less well understood. Using quantitative sensory testing (QST), we assessed the impact of a novel music app on specific aspects of nociceptive processing.

DESIGN

Within-subjects paired comparison of pain processing in control vs music condition.

SETTING

Human psychophysical laboratory.

SUBJECTS

Sixty healthy adult volunteers.

METHODS

Subjects were assessed for baseline anxiety, depression, and catastrophizing using validated questionnaires. QSTs measured included 1) pain threshold and tolerance to deep muscle pressure, 2) pain with mechanical pinprick, 3) temporal summation of pain (TSP) with a repeated pain stimulus, and 4) conditioned pain modulation (CPM) with a second painful stimulus. QSTs were performed in the absence and presence of music delivered through a music app.

RESULTS

We found an increase in pressure pain thresholds in both the forearm (P = 0.007) and trapezius (P = 0.002) with music, as well as a decrease in the amount of pinprick pain (P < 0.001) and TSP (P = 0.01) with music. Interestingly, CPM was also significantly diminished (P < 0.001) in the music condition. No significant difference in cold pain, anxiety, or situational catastrophizing was observed with music. Higher baseline pain catastrophizing scores were associated with less music-induced pressure pain reduction.

CONCLUSIONS

Several measures of mechanical pain sensitivity were reduced with music. TSP, a measure of central sensitization, also decreased with music, but CPM, a measure of descending modulation of pain, was not further augmented by music.

Neural activations during self-related processing in patients with chronic pain and effects of a brief self-compassion training - A pilot study

Chronic pain negatively affects psychological functioning including self-perception. Self-compassion may improve self-related functioning in patients with chronic pain but understanding of the neural mechanisms is limited. In this study, twenty patients with chronic low back pain read negative self-related situations and were instructed to be either self-reassuring or self-critical while undergoing fMRI. Patients rated their feelings of self-reassurance and self-criticism during each condition, and brain responses were contrasted with neutral instructions. Trait self-compassion measures (SCS) were also acquired. Brain activations during self-criticism and self-reassurance were localized to prefrontal, self- and emotion-processing areas, such as medial prefrontal cortex, dorsolateral prefrontal cortex (dlPFC), dorsal anterior cingulate cortex and posterior cingulate cortex. Self-reassurance resulted in more widespread and stronger activations relative to self-criticism. Patients then completed a brief self-compassion training (8 contact hours, 2 weeks home practice). Exploratory pre-post comparisons in thirteen patients found that feelings of self-criticism were significantly reduced and brain activations were greater in the anterior insula and prefrontal cortical regions such as dlPFC. Pre-post increases in dlPFC activation correlated with increased self-compassion (SCS), suggesting that early self-compassion skills might primarily target self-criticism via dlPFC upregulation. Future controlled studies on self-compassion training in chronic pain populations should extend these results.

Dynamic brain-to-brain concordance and behavioral mirroring as a mechanism of the patient-clinician interaction

The patient-clinician interaction can powerfully shape treatment outcomes such as pain but is often considered an intangible "art of medicine" and has largely eluded scientific inquiry. Although brain correlates of social processes such as empathy and theory of mind have been studied using single-subject designs, specific behavioral and neural mechanisms underpinning the patient-clinician interaction are unknown. Using a two-person interactive design, we simultaneously recorded functional magnetic resonance imaging (hyperscanning) in patient-clinician dyads, who interacted via live video, while clinicians treated evoked pain in patients with chronic pain. Our results show that patient analgesia is mediated by patient-clinician nonverbal behavioral mirroring and brain-to-brain concordance in circuitry implicated in theory of mind and social mirroring. Dyad-based analyses showed extensive dynamic coupling of these brain nodes with the partners' brain activity, yet only in dyads with pre-established clinical rapport. These findings introduce a putatively key brain-behavioral mechanism for therapeutic alliance and psychosocial analgesia.

Reliability and Validity of the Boston Bedside Quantitative Sensory Testing Battery for Neuropathic Pain

OBJECTIVE

Recent studies suggest that sensory phenotyping may provide critical information for the diagnosis and management of patients with chronic neuropathic pain (NP). However, many formal quantitative sensory testing (QST) paradigms require expensive equipment, a dedicated location, and substantial time commitments on the part of patient and examiner, highlighting the need for a convenient and portable "bedside" QST battery. We developed and tested a bedside QST battery in a sample of patients with chronic NP.

METHODS

Participants (N = 51) attended two in-person visits over approximately two weeks, during which they underwent QST using both laboratory-based equipment and simple, easily accessible bedside tools. Participants also completed questionnaires about their daily pain and NP symptoms.

RESULTS

Test-retest reliability estimates were highly statistically significant and did not differ between bedside (mean r = 0.60) and laboratory-based (mean r = 0.72) QST. Bedside QST variables and corresponding laboratory-based QST variables were highly correlated, suggesting adequate criterion validity for the bedside tests.

CONCLUSIONS

Results from the present study may have important implications for the sensory phenotyping and subsequent management of patients with chronic NP. Implementation of a protocol that uses inexpensive, portable, and convenient tools may allow for the application of QST in variety of clinical settings and advance NP research.

The relative contribution of pain and psychological factors to opioid misuse: A 6-month observational study

There is a pressing need to better understand the factors contributing to prescription opioid misuse among patients with chronic pain. Cross-sectional studies have been conducted in this area, but longitudinal studies examining the determinants of prescription opioid misuse repeatedly over the course of opioid therapy have yet to be conducted. The main objective of this study was to examine the relative contribution of pain and psychological factors to the occurrence of opioid misuse among patients with chronic pain prescribed opioids. Of particular interest was to examine whether pain intensity and psychological factors were more strongly associated with certain types of opioid misuse behaviors. Patients with chronic pain (n = 194) prescribed long-term opioid therapy enrolled in this longitudinal observational cohort study. Patients completed baseline measures and were then followed for 6 months. Opioid misuse was assessed once a month using self-report measures, and urine toxicology screens complemented patients' reports of opioid misuse. Heightened pain intensity levels were associated with a greater likelihood of opioid misuse (p = .014). However, pain intensity was no longer significantly associated with opioid misuse when controlling for psychological factors (i.e., negative affect, catastrophizing). Subsequent analyses revealed that higher levels of catastrophizing were associated with a greater likelihood of running out of opioid medication early, even after controlling for patients' levels of pain intensity and negative affect (p = .016). Our findings provide new insights into the determinants of prescription opioid misuse and have implications for the nature of interventions that may be used to reduce specific types of opioid misuse behaviors. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Pain catastrophizing and distress intolerance: prediction of pain and emotional stress reactivity

Exposure to stress is associated with poor outcomes in people with chronic pain. Dispositional variables, such as pain catastrophizing and distress intolerance, may impact reactivity to stressors. Importantly, these variables can be modified with treatment. The aim of this study was to investigate whether pain catastrophizing and distress intolerance were associated with tolerance of a pain stressor or a psychosocial stressor, and heightened negative affect following these stressors. A sample of 50 adults with chronic pain completed self-report measures and pain and psychosocial stress inductions. Results indicated that pain catastrophizing was associated with heightened anxiety during pain induction. Distress intolerance was associated with negative affect following a psychosocial stressor, and with poorer tolerance of the psychosocial stressor. Pain catastrophizing and distress intolerance are related factors, however, they exhibit distinct associations with amplification of pain and psychosocial stress reactivity. These variables may be important treatment targets in people with chronic pain.

A Mind-Body Physical Activity Program for Chronic Pain With or Without a Digital Monitoring Device: Proof-of-Concept Feasibility Randomized Controlled Trial

BACKGROUND

Chronic pain is associated with poor physical and emotional functioning. Nonpharmacological interventions can help, but improvements are small and not sustained. Previous clinical trials do not follow recommendations to comprehensively target objectively measured and performance-based physical function in addition to self-reported physical function.

OBJECTIVE

This study aimed to establish feasibility benchmarks and explore improvements in physical (self-reported, performance based, and objectively measured) and emotional function, pain outcomes, and coping through a pilot randomized controlled trial of a mind-body physical activity program (GetActive) with and without a digital monitoring device (GetActive-Fitbit), which were iteratively refined through mixed methods.

METHODS

Patients with chronic pain were randomized to the GetActive (n=41) or GetActive-Fitbit (n=41) programs, which combine relaxation, cognitive behavioral, and physical restoration skills and were delivered in person. They completed in-person assessments before and after the intervention. Performance-based function was assessed with the 6-min walk test, and step count was measured with an ActiGraph.

RESULTS

Feasibility benchmarks (eg, recruitment, acceptability, credibility, therapist adherence, adherence to practice at home, ActiGraph wear, and client satisfaction) were good to excellent and similar in both programs. Within each program, we observed improvement in the 6-min walk test (mean increase=+41 m, SD 41.15; P<.001; effect size of 0.99 SD units for the GetActive group and mean increase=+50 m, SD 58.63; P<.001; effect size of 0.85 SD units for the GetActive-Fitbit group) and self-reported physical function (P=.001; effect size of 0.62 SD units for the GetActive group and P=.02; effect size of 0.38 SD units for the GetActive-Fitbit group). The mean step count increased only among sedentary patients (mean increase=+874 steps for the GetActive group and +867 steps for the GetActive-Fitbit group). Emotional function, pain intensity, pain coping, and mindfulness also improved in both groups. Participants rated themselves as much improved at the end of the program, and those in the GetActive-Fitbit group noted that Fitbit greatly helped with increasing their activity.

CONCLUSIONS

These preliminary findings support a fully powered efficacy trial of the two programs against an education control group. We present a model for successfully using the Initiative on the Methods, Measurement, and Pain Assessment in Clinical Trials criteria for a comprehensive assessment of physical function and following evidence-based models to maximize feasibility before formal efficacy testing.

TRIAL REGISTRATION

ClinicalTrial.gov NCT03412916; https://clinicaltrials.gov/ct2/show/NCT03412916.

Acupuncture Treatment Modulates the Connectivity of Key Regions of the Descending Pain Modulation and Reward Systems in Patients with Chronic Low Back Pain

Chronic low back pain (cLBP) is a common disorder with unsatisfactory treatment options. Acupuncture has emerged as a promising method for treating cLBP. However, the mechanism underlying acupuncture remains unclear. In this study, we investigated the modulation effects of acupuncture on resting state functional connectivity (rsFC) of the periaqueductal gray (PAG) and ventral tegmental area (VTA) in patients with cLBP. Seventy-nine cLBP patients were recruited and assigned to four weeks of real or sham acupuncture. Resting state functional magnetic resonance imaging data were collected before the first and after the last treatment. Fifty patients completed the study. We found remission of pain bothersomeness in all treatment groups after four weeks, with greater pain relief after real acupuncture compared to sham acupuncture. We also found that real acupuncture can increase VTA/PAG rsFC with the amygdala, and the increased rsFC was associated with decreased pain bothersomeness scores. Baseline PAG-amygdala rsFC could predict four-week treatment response. Our results suggest that acupuncture may simultaneously modulate the rsFC of key regions in the descending pain modulation (PAG) and reward systems (VTA), and the amygdala may be a key node linking the two systems to produce antinociceptive effects. Our findings highlight the potential of acupuncture for chronic low back pain management.