# Bridging the Gap in Pain Measurement with a Brain-Based Index

## TL;DR

This paper introduces Piqβ, an EEG-based index that objectively measures pain intensity, offering a more accurate and equitable alternative to self-reporting.

## Contribution

Piqβ is a novel EEG-based index that objectively identifies and quantifies pain using beta-band cortical activity.

## Key findings

- Piqβ achieved 97.8% sensitivity and 88.2% specificity with an optimal cutoff of 10%.
- Piqβ correlated with self-reported pain scores (ρ = 0.60, p < 0.0001) with acceptable agreement.
- Piqβ can track intra-individual pain fluctuations over time and classify pain into five intensity levels.

## Abstract

Public health relevance—How does this work relate to a public health issue?
Pain intensity assessment relies mainly on self-report or clinician-based reporting, which limits accuracy in several clinical contexts.Piqβ is introduced as an EEG-based index derived from beta-band cortical activity that objectively identifies and quantifies pain.

Pain intensity assessment relies mainly on self-report or clinician-based reporting, which limits accuracy in several clinical contexts.

Piqβ is introduced as an EEG-based index derived from beta-band cortical activity that objectively identifies and quantifies pain.

Public health significance—Why is this work of significance to public health?
Chronic pain is a major global burden that contributes to polypharmacy, addiction, and reduced social participation.Piqβ may help strengthen the physiological validation of pain intensity, support recognition of the patient’s pain experience, and offer an additional element for rehabilitation strategies.

Chronic pain is a major global burden that contributes to polypharmacy, addiction, and reduced social participation.

Piqβ may help strengthen the physiological validation of pain intensity, support recognition of the patient’s pain experience, and offer an additional element for rehabilitation strategies.

Public health implications—What are the key implications or messages for practi-tioners, policy makers and/or researchers in public health?
Piqβ can promote more equitable pain assessment by supporting clinical decision-making when self-report is limited, inconsistent, or unavailable.Piqβ provides a consistent, standardized method for capturing physiological correlates of pain. It does not assume uniform pain experiences but ensures methodological consistency, enabling comparison while respecting their inherent variability.

Piqβ can promote more equitable pain assessment by supporting clinical decision-making when self-report is limited, inconsistent, or unavailable.

Piqβ provides a consistent, standardized method for capturing physiological correlates of pain. It does not assume uniform pain experiences but ensures methodological consistency, enabling comparison while respecting their inherent variability.

(1) Background: Pain assessment still relies primarily on subjective self-report. To address these limitations, we developed Piq, an EEG-based index derived from beta-band brain activity (Piqβ) aimed at providing objective pain identification and quantification. (2) Methods: The study combined cross-sectional and longitudinal designs. Resting-state brain activity was recorded for five minutes, and EEG signals were preprocessed using a dedicated algorithm. Piqβ performance was assessed by identifying an optimal cutoff to discriminate pain from no pain, evaluating its association with VNRS, and estimating agreement using a modified concordance criterion (exact match or ±1 category). A graded scale was also established to classify pain into distinct categories, according to intensity. (3) Results: An optimal cutoff of 10% for Piqβ yielded 97.8% sensitivity and 88.2% specificity. Piqβ correlated with self-reported scores (ρ = 0.60, p < 0.0001) with acceptable agreement (mean bias −1.02), accounting for clinically acceptable discrepancies. Five levels of pain were proposed, and Piqβ demonstrated the ability to track intra-individual fluctuations over time, accounting for clinically acceptable discrepancies. (4) Conclusions: These findings provide strong evidence to support the Piqβ index as a valuable complement to subjective pain ratings.