CompletedNot Applicable

Session-Order Sensitivity of TS and OA in a Capsaicin Crossover Model

Canada16 participantsStarted 2024-05-01

Plain-language summary

Temporal summation (TS) and offset analgesia (OA) are widely used psychophysical endpoints in pain research that index different components of central nociceptive processing. While crossover designs are commonly used in experimental pain studies to reduce between-participant variability, the design-stability of these endpoints under repeated testing during experimental sensitisation is not well characterised. This study compared the design-stability of mechanical TS (Sumscore) and offset analgesia magnitude (OffA) in a two-period, vehicle-controlled crossover trial of capsaicin-evoked secondary hyperalgesia in healthy adults. The primary aim was methodological: to determine whether session-order effects differ between TS and OffA when these are used as outcome measures in two-period crossover designs of capsaicin-induced central sensitisation. Topical capsaicin was used as a reversible experimental intervention to create a controlled, transient state of secondary hyperalgesia rather than as a therapeutic intervention. The study informs endpoint selection in future quantitative sensory testing (QST) crossover trials.

Who can participate

Age range

18 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * Healthy adult volunteers (≥18 years of age) * Able to provide written informed consent in English Exclusion Criteria: * Current or chronic pain * Neurological disease * Skin conditions or sensitivity over the test sites to capsaicin * Contraindications to thermal stimulation of the skin * Musculoskeletal conditions that could alter somatosensory processing * Use of analgesic medications within 24 hours prior to each session * Use of caffeine within 24 hours prior to each session * Use of alcohol within 24 hours prior to each session

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Mechanical temporal summation (Sumscore)

Timeframe: Baseline and 10, 20, 30, and 40 min post-intervention (within each of two sessions, separated by a minimum 1-week washout)

Offset analgesia magnitude (OffA)

Timeframe: Baseline and 10, 20, 30, and 40 min post-intervention (within each of two sessions, separated by a minimum 1-week washout)

Trial details

NCT IDNCT07625475

SponsorUniversity of Guelph

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2025-04-30

View on ClinicalTrials.gov More Hyperalgesia trials

Plain-language summary

Who can participate

Age range

18 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

What they're measuring

Mechanical temporal summation (Sumscore)

Timeframe: Baseline and 10, 20, 30, and 40 min post-intervention (within each of two sessions, separated by a minimum 1-week washout)

Offset analgesia magnitude (OffA)

Timeframe: Baseline and 10, 20, 30, and 40 min post-intervention (within each of two sessions, separated by a minimum 1-week washout)