Instrument
Description
Advantages
Disadvantages
Considerations in OUD
Study Examples
Self-Report Instruments Self-Report Instruments Self-Report Instruments Self-Report Instruments Self-Report Instruments Self-Report Instruments
Visual Analogue Scale (VAS) 1921
A 10-cm line ranging from ”no pain to ”worst pain imaginable”. The patient marks a point on the line to indicate their pain level
- Allows for a wide range of responses, and can be used for non-verbal communication of pain - Sensitive to small changes209 - Relies on patients’ subjective perception - Cannot be administered verbally - Difficult conceptualization for some patients. - Unidimensional
Subjective pain reporting may be affected by tolerance and hyperalgesia
Muriel et al. (2023)104 Nielsen et al. (2017)105 Veldman et al. (2022)106
Numeric Rating Scale (NRS) 1978
Patients rate their pain on a scale from 0 (no pain) to 10 (worst possible pain)
- Simple and easy to use - Can be performed verbally in telephone interviews210 - Relies on patients’ subjective perception - May lack sensitivity due to restricted range211 - Unidimensional
Restricted range may fail to capture nuances for patients with altered pain perception
Latiff et al. (2021)114
Brief Pain Inventory (BPI) 1982
Questionnaire that measures both intensity of pain (sensory dimension) and interference of pain (reactive dimension)
- Multidimensional - Assesses functionality impairments - Short and simple format
- Longer to complete than the VAS or NRS
Useful for capturing multidimensional nature of pain in OUD patients, including functional impairment
Hall et al. (2022)120
McGill Pain Questionnaire 1999
Questionnaire that measures multiple pain domains
- Multidimensional - Assesses impairments in function, mood, social life, and sleep
- Longer to complete than the BPI
Useful for capturing details regarding the nature of pain in OUD patients, beyond functional impairments
De Aquino et al. (2023)122 Latif et al. (2019)123
Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques Clinical, Psychophysical, Neurophysiological, and Neuroimaging Techniques
Behavioral Observations
Observable pain-related behaviors such as facial expressions, body language, changes in interpersonal interactions and changes in activity level as measured by actigraphy and pedometers
- Not self-reported - Useful for patients unable to communicate - Behaviors can be ambiguous - Difficult to quantify - Prone to observer bias126
Opioid-induced hyperalgesia can complicate interpretation of behavioral reactions to pain stimuli
Teeters et al. (2021)130 Salgado García et al. (2022)132 Lambert et al. (2022)133 Bertz et al. (2019)134
Physiological Indicators
Objective measures of bodily function such as heart rate, blood pressure, and respiratory rate
- Not self-reported - Useful for patients unable to communicate - Nonspecific - Many factors can influence physiological responses - Equipment required
Opioid-induced physiological changes, and withdrawal may confound interpretation
Roberts et al. (2022)145 Levin et al. (2019)146
Quantitative Sensory Testing (QST)
Series of standardized tests that quantify sensory experiences. Can use heat, cold, mechanical, or pressure stimuli
- QST is useful for pain phenotyping, assessing threshold, tolerance, habituation, and summation - Helpful to diagnose hyperalgesia - Not yet optimized for daily clinical usual - Clinical usability data is incipient
QST is a rising tool for assessing opioid phenomena, but its use is yet limited to research settings
Prosser et al. (2018)152 Edwards et al. (2011)156 Compton et al. (2020)157
Functional MRI
Brain imaging that captures changes in blood flow as a proxy for brain activity.
- Can provide insight into which brain areas respond to certain stimuli and tasks - May serve for validation of therapy responses - Correlation of brain activation does not necessarily imply a causal relationship - Less available, higher costs
Limited clinically relevant results for the understanding and treatment of OUD in its current state. Findings may be used as biomarkers in the future.
Faraj et al. (2021)164
Electroencephalogram (EEG)
Technique using measurable electrical signals in the nervous system that originate from a controlled stimulus
- Relatively cheap and easy to employ, readily available - Can be used with other measures in a singular session (e.g., actigraphy) - Does not provide the same spatial resolution and anatomical localization as neuroimaging - Gathers superficial cortical electrical activation, not inclusive of deeper brain structures.
Emerging use as a biomarker in OUD studies, for example as a predictor of opioid analgesic response
Huhn et al. (2022)177