Patients with fibromyalgia (N=103) and matched healthy control participants (N=34)
Conditions
Interventions
In a lab procedure, nocebo effects will be induced with the associative learning mechanism of classical conditioning combined with verbal suggestions. In the learning phase of the conditioning paradig
Sponsors
Leiden University
Eligibility
Inclusion criteria
Inclusion criteria: Participants must meet all of the following criteria: • Female • Age18-65 • Fluent in Dutch language (written and spoken) • Able to give informed consent Additionally, for patients: • Fibromyalgia diagnosis by a rheumatologist, as reported by the patient and as verified by provision of the date, location, and provider of the diagnosis.
Exclusion criteria
Exclusion criteria: Participants will be excluded for the following criteria: • Pregnancy or breastfeeding • Color blindness • Injuries/open wounds on the non-dominant hand or arm on the day of laboratory session • Carrying a pacemaker/implanted pumps • Having implanted metals on the non-dominant hand or arm • Refusal/inability to remove possible artificial nails or nail polish covering the thumbnail Specific for patients, additionally: • A medical diagnosis other than fibromyalgia explaining the chronic pain symptoms • Severe physical or mental co-morbidities that are not related to fibromyalgia symptoms (e.g., DSM-V diagnosis of psychosis, suicidal ideation, addiction) • Use of painkillers different than usual dose of treatment on the day of experimentation Specific for healthy controls, additionally: • Chronic pain complaints =3 months in the past or present or a diagnosis of fibromyalgia • Current pain • Severe physical or psychiatric co-morbidities that may interfere with the study protocol (e.g., DSM-V diagnosis) • Use of painkillers within 24 hours before the day of experimentation
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Nocebo effects will be calculated by taking the mean difference of pain scores (0-10 NRS) in the experimental and control trials of each testing phase. Nocebo effects will be calculated separately for conditioning and extinction parts. The recovery from nocebo effects, i.e., reduction of nocebo effects, will be calculated by taking the difference in nocebo effects after conditioning and after extinction. Part 1: The role of nocebo effects (primary predictor) in the changes in primary outcome measure (clinical pain levels, i.e., pain severity questions from Brief Pain Inventory) will be assessed in patients from baseline to one-year follow-up. Part 2: To get a more in-depth understanding of group differences in learning nocebo manipulations, the average pain scores in experimental and control trials from the testing phase of conditioning will be compared between groups, instead of a direct comparison of nocebo effects. Part 3: Within-group stability of nocebo effects will be assessed by comparing per group the average pain scores in experimental and control trials from the testing phases (conditioning) in baseline and one-month follow-up. | — |
Secondary
| Measure | Time frame |
|---|---|
| Part 1: The role of nocebo effects (primary predictor) in the changes in secondary outcome measures (fibromyalgia disability, i.e., Fibromyalgia Impact Questionnaire, and daily pain fluctuations, i.e., ESM) will be assessed from baseline to one-year. Also, the role of reduction in nocebo effects (secondary predictor) in the changes in primary and secondary outcome measures will be assessed from baseline to one-year follow-up. Part 2: Nocebo effects calculated after conditioning and after extinction will be compared between groups. Part 3: The stability of pain scores in experimental and control trials from the testing phase of conditioning will be compared between groups. Additionally, the stability of calculated nocebo effects after extinction will be compared within and between groups. | — |
Contacts
Public ContactAndrea Evers
Leiden University
Outcome results
None listed