Background & Aims

Treatments for pain have modest effects. It is plausible that treatment outcomes could be improved if treatments are matched to the mechanisms that underlie an individual’s persistence of pain. The IASP defines three pain descriptors that are argued to involve different mechanisms – Nociceptive, Neuropathic and Nociplastic. Although treatments are available to address each mechanism, there is not yet consensus on how to differentiate between them in clinical practice. Recent work has systematically reviewed the literature to identify features and methods that might enable discrimination between mechanism [3], and then examined expert consensus on features that are likely to be unique to a mechanism or shared between two but not all three mechanisms [4]. This study aimed to identify the rank and relative weight of each item with the aim to derive data to inform the development of a multimodal tool to aid discrimination between mechanisms in clinical practice.

Methods

This study was undertaken in collaboration with the Terminology Task Force of the IASP (25 members) and a panel of experts from diverse disciplines, countries, cultures, and career stages. The list of features was presented to the Task Force and Expert Panel members using 1000minds software. The decision analytic software applies choice-based conjoint analysis to evaluate, through discrete pairwise choices, the weights for each item. For each mechanism, pairs of scenarios were presented, each with information relevant to two items. Experts anonymously nominated which scenario was most likely to indicate pain explained predominantly by that mechanism. Efficiency is gained by eliminating presentation of pairs that can be implicitly understood based on explicitly presented corollaries. Using the discrete choices, the relative importance of items is evaluated mathematically to generate weights for each item.

Results

Highly ranked features identified were: (1) Nociceptive pain – Consistently provoked by movements and postures; proportional pattern of pain provocation; Localized distribution; No generalized hypersensitivity, (2) Neuropathic pain – Diagnostic tests confirm evidence of somatosensory lesion/disease; Pain associated with sensory signs of lesion/disease (negative – numbness; positive – hyperesthesia); Pain descriptors related to lesion of somatosensory nervous system; Pain in a neuroanatomically plausible distribution, and (3) Nociplastic pain – Diffuse, widespread, multi-site non-neuroanatomical pain distribution; Generalized hypersensitivity; Multi-site pain; Multiple somatic symptoms (fatigue, sleep, mood, cognitive), Non-neuroanatomically plausible distribution of pain.

Conclusions

The highest ranked features for Neuropathic and Nociplastic pain are consistent with the published IASP Clinical Criteria [1,2]. The next step will involve development of an algorithm for a multimodal tool using the derived item weights, followed by validation and assessment of psychometric properties.

References

[1] Finnerup NB et al. Pain 2016;157(8):1599-1606.
[2] Kosek E et al. Pain 2021;162(11):2629-2634.
[3] Shraim MA et al. Pain 2021;162(4):1007-1037.
[4] Shraim MA et al. Pain 2022;163(9):1812-1828.

Presenting Author

Paul Hodges

Poster Authors

Paul Hodges

PhD

The University Of Queensland

Lead Author

E-mail

Muath Shraim

The University of Queensland

Lead Author

E-mail

Michele Sterling

RECOVER Injury Research Centre, The University of Queensland, Queensland, Australia

Lead Author

E-mail

Kathleen Sluka

PT

University of Iowa, Carver College of Medicine

Lead Author

E-mail

Topics

  • Assessment and Diagnosis