Pain assessment in context: a state of the science review of the McGill pain questionnaire 40 years on

Discovery and validation of biomarkers to aid the development of safe and effective pain therapeutics: challenges and opportunities

Pain medication plays an important role in the treatment of acute and chronic pain conditions, but some drugs, opioids in particular, have been overprescribed or prescribed without adequate safeguards, leading to an alarming rise in medication-related overdose deaths. The NIH Helping to End Addiction Long-term (HEAL) Initiative is a trans-agency effort to provide scientific solutions to stem the opioid crisis. One component of the initiative is to support biomarker discovery and rigorous validation in collaboration with industry leaders to accelerate high-quality clinical research into neurotherapeutics and pain. The use of objective biomarkers and clinical trial end points throughout the drug discovery and development process is crucial to help define pathophysiological subsets of pain, evaluate target engagement of new drugs and predict the analgesic efficacy of new drugs. In 2018, the NIH-led Discovery and Validation of Biomarkers to Develop Non-Addictive Therapeutics for Pain workshop convened scientific leaders from academia, industry, government and patient advocacy groups to discuss progress, challenges, gaps and ideas to facilitate the development of biomarkers and end points for pain. The outcomes of this workshop are outlined in this Consensus Statement.

The Multimodal Assessment Model of Pain: A Novel Framework for Further Integrating the Subjective Pain Experience Within Research and Practice

OBJECTIVES

Pain assessment is enigmatic. Although clinicians and researchers must rely upon observations to evaluate pain, the personal experience of pain is fundamentally unobservable. This raises the question of how the inherent subjectivity of pain can and should be integrated within assessment. Current models fail to tackle key facets of this problem, such as what essential aspects of pain are overlooked when we only rely on numeric forms of assessment, and what types of assessment need to be prioritized to ensure alignment with our conceptualization of pain as a subjective experience. We present the multimodal assessment model of pain (MAP) as offering practical frameworks for navigating these challenges.

METHODS

This is a narrative review.

RESULTS

MAP delineates qualitative (words, behaviors) and quantitative (self-reported measures, non-self-reported measures) assessment and regards the qualitative pain narrative as the best available root proxy for inferring pain in others. MAP offers frameworks to better address pain subjectivity by: (1) delineating separate criteria for identifying versus assessing pain. Pain is identified through narrative reports, while comprehensive assessment is used to infer why pain is reported; (2) integrating compassion-based and mechanism-based management by both validating pain reports and assessing underlying processes; (3) conceptualizing comprehensive pain assessment as both multidimensional and multimodal (listening/observing and measuring); and (4) describing how qualitative data help validate and contextualize quantitative pain measures.

DISCUSSION

MAP is expected to help clinicians validate pain reports as important and legitimate, regardless of other findings, and help our field develop more comprehensive, valid, and compassionate approaches to assessing pain.

A QST-based Pain Phenotype in Adults With Sickle Cell Disease: Sensitivity and Specificity of Quality Descriptors

BACKGROUND

We sought to refine a screening measure for discriminating a sensitized or normal sensation pain phenotype among African American adults with sickle cell disease (SCD).

OBJECTIVE

To develop scoring schemes based on sensory pain quality descriptors; evaluate their performance on classifying patients with SCD who had sensitization or normal sensation, and compare with scores on the Self-report Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) and the Neuropathic Pain Symptom Inventory (NPSI).

METHODS

Participants completed PAINReportIt, quantitative sensory testing (QST), S-LANSS, and NPSI. Conventional binary logistic regression and least absolute shrinkage and selection operator (lasso) regression were used to obtain 2 sets of weights resulting in 2 scores: the PR-Logistic (PAINReportIt score weighted by conventional binary logistic regression coefficients) and PR-Lasso (PAINReportIt score weighted by lasso regression coefficients). Performance of the proposed scores and the existing scores were evaluated.

RESULTS

Lasso regression resulted in a parsimonious model with non-zero weights assigned to 2 neuropathic descriptors, cold and spreading. We found positive correlations between the PR-Lasso and other scores: S-LANSS (r = 0.22, P < 0.01), NPSI (r = 0.22, P < 0.01), and PR-Logistic (r = 0.35, P < 0.01). The NPSI and PR-Lasso performed similarly at different levels of required specificity and outperformed the S-LANSS and PR-Logistic at the various specificity points.

CONCLUSION

The PR-Lasso offers a way to discriminate a SCD pain phenotype.

Multidimensional investigation of chronic pain experience and physical functioning following hip fracture surgery: clinical implications

Introduction

Older adults experience significant chronic pain after hip fracture, resulting in decreased physical functioning. However, pain investigation in this population is mostly limited to self-reported pain intensity. Detailed pain assessment may identify intervention targets other than pain relief. The aim of this study is to investigate multiple dimensions of pain experience (intensity, sensory, affective, evaluative and miscellaneous dimensions) and to correlate them to lower limb functionality and limitations in daily living activities.

Methods

We conducted a cross-sectional study of 50 older adults (77.1 ± 8.1 years old) who underwent hip fracture surgery in the past 4 months. We used the Numeric Rating Scale (NRS), the McGill Pain Questionnaire (MPQ) and an algometer to assess pain intensity, pain quality and pressure pain threshold, respectively. Lower limb functionality and limitation in basic (activities of daily living (ADL)) and instrumental activities of daily living (IADL) were assessed using the Short Physical Performance Battery (SPPB) and the Brazilian OARS Multidimensional Functional Assessment Questionnaire.

Results

Participants described pain as brief, momentary and transient, especially during weight-bearing activities. Although the pain intensity measured by the NRS was reported as moderate to severe (7.5 ± 1.6 points), it was not correlated with physical functioning. However, we observed a moderate negative correlation between pressure pain threshold, ADL and IADL disability (r = -0.41, p < 0.01). Among pain qualities, the sensory category was moderately negatively correlated to SPPB (r = -0.41, p < 0.01), and the evaluative category was moderately correlated to ADL and IADL disability (r = 0.43, p < 0.01).

Conclusion

Pain can be present 4 months after hip fracture surgery, particularly during weight-bearing activities, and it is associated with poor lower limb functionality, as well as ADL and IADL disability. Older adults may benefit from pain assessments that go beyond pain intensity measurements after hip fracture, as this helps clinicians optimise pain management and overall functional recovery.

Cross-cultural Adaptation and Validation of the Norwegian Short-form McGill Pain Questionnaire-2 in Low Back-related Leg Pain

STUDY DESIGN

A prospective observational study with translation and psychometric analyses of a questionnaire.

OBJECTIVE

Cross-cultural adaptation of the Short-Form McGill Pain Questionnaire-2 into Norwegian.

SUMMARY OF BACKGROUND DATA

The different versions of the McGill Pain Questionnaire (MPQ) have been important and influential tools for pain assessment. To more reliably assess qualities of both neuropathic and non-neuropathic pain, the Short-Form MPQ was revised in 2009 (SF-MPQ-2), including seven additional descriptors. No Norwegian adaptation of the SF-MPQ-2 has been performed.

METHODS

A translation of the SF-MPQ-2 was performed based on established guidelines. Forward-translations were compared and discussed in an expert workgroup. A synthesis was achieved by consensus. A backward translation was reviewed and consolidated with the forward translations to confirm linguistic equivalence. A prefinal version was tested in eight patients, who were interviewed to evaluate acceptability and comprehension of the questionnaire. Minor changes were implemented. The questionnaire was externally proofread. The final Norwegian version (NSF-MPQ-2) was tested for content and construct validity and internal consistency reliability in a population with low back-related leg pain.

RESULTS

The backward translation was in good accordance with the original version. The prefinal version showed excellent acceptability and comprehension in initial patient-testing. The NSF-MPQ-2 showed satisfactory content and construct validity, including responsiveness to change, and acceptable internal consistency reliability as measured by Cronbach's alpha. A confirmatory factor analysis showed poor fit for the established four-factor structure, especially regarding the neuropathic subscale.

CONCLUSION

The NSF-MPQ-2 showed excellent acceptability and comprehension, satisfactory content and construct validity, including responsiveness to change, and internal consistency reliability as measured by Cronbach's alpha. However, a confirmatory factor analysis raised concerns regarding the factor-structure in the present population. Until more evidence emerges for the four-factor solution we suggest the NSF-MPQ-2 should be used as a single measure.

LEVEL OF EVIDENCE

3.

Vaginal bromocriptine improves pain, menstrual bleeding and quality of life in women with adenomyosis: A pilot study

INTRODUCTION

Adenomyosis is a benign uterine disease where endometrial glands and stroma are found within the myometrium surrounded by an area of hypertrophic myometrium. Symptomatology includes heavy menstrual bleeding and pelvic pain. The pathogenesis of adenomyosis is not known; however, animal models have shown increased uterine concentration of prolactin as a risk factor. Prolactin acts as a smooth muscle cell mitogen. If prolactin is central to adenomyosis pathogenesis, reducing uterine prolactin could be a possible medical treatment option. In this pilot study, we aim to evaluate the effect of bromocriptine, a prolactin inhibitor, on menstrual bleeding and pain in women with adenomyosis.

MATERIAL AND METHODS

23 women with diffuse adenomyosis were enrolled from a university hospital in Sweden and a tertiary care center in the USA. Nineteen patients completed 6 months of treatment with vaginal bromocriptine at a dose of 5 mg daily. Participants completed validated measures at baseline, 3 and 6 months of treatment, and at 9 months (3 months after cessation of bromocriptine). Validated measures utilized included Pictorial Blood Loss Assessment Chart (PBLAC), Aberdeen Menorrhagia Clinical Outcomes Questionnaire (AMCOQ), Visual Analog Scale for pain (VAS), McGill Pain Questionnaire (MPQ), Endometriosis Health Profile (EHP-30), Female Sexual Function Index (FSFI) and the Fibroid Symptom Quality of Life (UFS-QOL) symptom severity and health-related quality of life (HRQL) subscores. Scores were compared between baseline and 9 months using the Wilcoxon signed rank test.

RESULTS

Mean age of participants was 44.8 years. About 77.8% reported PBLAC scores >250 and 68.4% reported moderate to severe pain at baseline. Compared with baseline, women had lower 9-month scores (median [interquartile range] for all) on PBLAC (baseline 349 [292-645] vs 9-month 233 [149-515], P = 0.003), VAS (5.0 [4-8.3] vs 2.5 [0-4.5], P < 0.001), EHP Core Pain (15.9 [9.1-50.0] vs 3.4 [2.3-34.1], P = 0.029), EHP Core Self-image (41.7 [16.7-58.3] vs 25 [0-5], P = 0.048) and Symptom Severity Score (60 [44-72] vs 44 [25-56], P < 0.001) and higher HRQL scores (57 [37-63] vs 72 [51-85], P < 0.001) following bromocriptine treatment. Other EHP core parameters and FSFI were not significantly different.

CONCLUSIONS

Significant improvement in menstrual bleeding, pain and quality of life after vaginal bromocriptine treatment suggests a novel therapeutic agent for adenomyosis.

The language of chronic pain

OBJECTIVE

Pain is a universal phenomenon, but is also inherently private and subjective - there's no objective test for its existence. Sufferers rely on language to describe their pain experience. The McGill Pain Questionnaire paved the way for incorporating language into pain assessment and recent research has explored aspects of pain language such as metaphors and grammatical patterns. This study investigated how chronic pain sufferers use language to describe their pain experience.

DESIGN

Three focus groups were conducted (N = 16, age 22-74 years, M = 46.6 years) with participants attending an outpatient chronic pain management program in Sydney, Australia. Participants were asked to describe aspects of their pain experience.

MAIN OUTCOME MEASURE

The language which participants utilized to talk about their pain experience.

RESULTS

Thematic analysis identified five superordinate themes: Isolation, Physical Sensations of Pain, Pain Personified, Pain as Overwhelming, and Coping with Pain. Across themes, participants relied on metaphorical language, which reflects the complex, multidimensional aspects of pain as well as the desire to effectively communicate it to others.

CONCLUSIONS

This study underscores research indicating the complexity of pain experience and hence pain language, and suggests that single word adjectival measures are inadequate to completely capture its complexity. IMPLICATIONS FOR REHABILITATION Chronic pain is now considered a disease in and of itself, with patient's pain language being an important study area due to the lack of objective tests for pain. In both assessment and rehabilitation, patients rely on metaphorical pain language in order to facilitate understanding and garner support from others. Pain metaphors may provide a useful target for interventions such as Acceptance and Commitment Therapy and Cognitive Behavioural Therapy, particularly when addressing catastrophic thinking patterns.

Both ipsilateral and contralateral localized vibratory stimulations modulated pain-related sensory thresholds on the foot in mice and humans

Purpose

This study was aimed to investigate the effect of localized vibration on sensory thresholds in mice and humans using a novel quantitative method.

Participants and methods

The sensory thresholds of 7-week-old male C57BL/6J mice were measured with four sine-wave electrostimulation frequencies (5, 50, 250, and 2,000 Hz) before and after applying 2-minute vibration to the plantar side of the foot in mice. In human participants (16 males and 16 females; mean age, 21.0±0.8 years), the sensory threshold was measured at 50 Hz before and after applying 2-minute and 5-minute vibrations to the dorsal side of the foot.

Results

Application of a 2-minute vibration at either the ipsilateral or contralateral side modulated the sensory thresholds elicited by a 5- or 50-Hz right electrostimulation in mice. In human participants, application of a 5-minute vibration at either the ipsilateral or contralateral side modulated the sensory threshold elicited by 50-Hz right electrostimulation, but had no effect on local skin temperature. These results suggest that the right side of pain-related Aδ fibers (50 Hz) or C fibers (5 Hz) was modulated by the localized ipsilateral or contralateral side of vibratory stimuli, respectively, in mice and humans.

Conclusion

The ability of contralateral vibration to modify the right sensory thresholds suggests possible involvement of the central nervous system in vibratory modulation.

The psycholinguistic and affective structure of words conveying pain

Despite the flourishing research on the relationships between affect and language, the characteristics of pain-related words, a specific type of negative words, have never been systematically investigated from a psycholinguistic and emotional perspective, despite their psychological relevance. This study offers psycholinguistic, affective, and pain-related norms for words expressing physical and social pain. This may provide a useful tool for the selection of stimulus materials in future studies on negative emotions and/or pain. We explored the relationships between psycholinguistic, affective, and pain-related properties of 512 Italian words (nouns, adjectives, and verbs) conveying physical and social pain by asking 1020 Italian participants to provide ratings of Familiarity, Age of Acquisition, Imageability, Concreteness, Context Availability, Valence, Arousal, Pain-Relatedness, Intensity, and Unpleasantness. We also collected data concerning Length, Written Frequency (Subtlex-IT), N-Size, Orthographic Levenshtein Distance 20, Neighbor Mean Frequency, and Neighbor Maximum Frequency of each word. Interestingly, the words expressing social pain were rated as more negative, arousing, pain-related, and conveying more intense and unpleasant experiences than the words conveying physical pain.

Mood Spectrum Disorders and Perception of Pain

Evaluation of pain perception in chronic pain patients with a concomitant mood-spectrum disorder.

DESIGN

The observational retrospective study is based on patient data collected in psychosomatic consultations held at the Gift Institute for Integrative Medicine in Pisa, Italy, from 2002 to 2014. Evoked pain stimulus threshold and tolerance were evaluated using the cold pressor test. Clinical pain intensity and Sensorial, Affective, and Evaluative dimensions were assessed using the Italian Pain Questionnaire, and Anxiety and Depressive symptoms using the Hospital Anxiety Depression Scale. Mood-spectrum disorders were diagnosed via the Mini-International Neuropsychiatric Interview, and affective temperament in accordance with Akiskal and Pinto's criteria (1999). Of a total of 627 chronic pain clinic patients, 381 were diagnosed with a concomitant mood-spectrum (MS) disorder, unipolar (US) in 61.41%. Pain threshold (t = 2.28; p < 0.05) was lower, and all clinical pain dimensions (t = 2.28; p < 0.05) increased, in MS patients compared to those without psychiatric disorders. Pain intensity (F = 3.5, p < 0.05) and cognitive pain component scores (F = 7.84; p < 0.0001) were higher in US and, to a lesser extent Bipolar Spectrum, than in subjects with other (n.112) or no psychiatric disorders (n. 134). Suicide ideation was highest in US (F = 37.20; p < 0.0001), although in BS major depressive episodes had more melancholic features (F = 46.73; P < 0.0001), and a longer history of psychiatric disorders before the pain onset than US (F = 20.31; p < 0.0001). Pain management should take into account pre-existing psychiatric disorders.