Ignite Creation Date:
2024-05-06 @ 2:39 PM
Last Modification Date:
2024-10-26 @ 1:35 PM
Study NCT ID:
NCT04387851
Status:
COMPLETED
Last Update Posted:
2022-01-11
First Post:
2020-05-11
Brief Title:
Learning Mechanisms for Placebo and Nocebo Studies on Somatosensory Sensations a Systematic Review and Meta-analysis
Sponsor:
Leiden University Medical Center
Organization:
Leiden University Medical Center
Study Overview
Official Title:
Learning Mechanisms for Placebo and Nocebo Studies on Somatosensory Sensations a Systematic Review and Meta-analysis
Status:
COMPLETED
Status Verified Date:
2022-01
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
Placebo and nocebo effects are defined as the positive and negative effects occurring after the supposed administration of an inert treatment which through a given learning process is believed to have positive or negative effects The objective of this study is to summarize the available knowledge on experimental inductions of placebo and nocebo effects on somatosensory sensations specifically pain and itch The aim isto investigate the extent to which learning processes such as conditioning and verbal suggestions induce placebo and nocebo effects on pain and itch in healthy humans The researchers intent to examine expectancy induction methods for placebo and nocebo effects on somatosensory sensations describe methodological attributes of the research and propose practical and theoretical implications as well as future directions for research investigating placebo and nocebo effects on somatosensory sensations
Detailed Description:
Research questions include
1 What is the average magnitude of placebo or nocebo effects on pain and on itch across included studies
2 Across studies that tested multiple learning processes for placebo and nocebo effects on pain is the magnitude of a placebo or nocebo effect on pain different based on the learning process used to induce the effect
3 Does the magnitude of placebo or nocebo effects differ between the sensations of pain and itch
4 Are nocebo effects on pain and itch stronger than placebo effects on pain and itch as measured by their relative magnitude
Dependent upon search results the researchers intend to answer questions 1 and 2 with meta-analysis and questions 3 and 4 with systematic review
Search Strategy
PubMed PsycINFO EMBASE and the Cochrane CENTRAL Methodology Library will be searched Languages are restricted to English Dutch and German Publication period is not restricted Searches were initially conducted on March 18th 2019 The detailed key-worded search strategy will not be made publicly available until this review is complete
Condition or domain being studied
Experimental induction of placebo or nocebo effects on somatosensory sensations ie pain andor itch For the purposes of in- and exclusion studies are considered to have induced a placebo or nocebo effect if the supposed administration of an inert treatment is paired with a given learning process attempt to induce positive or negative outcome-effects
Participantspopulation
Healthy adult human volunteers Patient samples will not be included to improve homogeneity of the results
Data extraction
Titles and abstracts of articles retrieved using the search strategy and those from additional sources will be screened by two independent reviewers to identify studies that potentially meet the inclusion criteria outlined above The full text of these articles and articles about which doubts exist based on the title andor abstract will be retrieved and assessed for eligibility by two independent reviewers Full texts that are considered to be possibly eligible for inclusion or about which doubts exist will also be assessed for eligibility by a third reviewer Two independent reviewers will use a standardized form to extract data from the included studies to derive study characteristics assess study quality and for data analysis Extracted information will include details of the intervention control condition study population sensation type and how sensations were measured eg self-report type of experimental induction ie learning method used type of expectancy ie placebo or nocebo information for quality assessment and outcome data for meta-analysis eg sample size mean and standard deviation Doubts regarding data-extraction will be resolved through discussion with a second review author Missing data will be requested from the study authors
Risk of bias assessment
Risk of bias will be assessed using the method developed by Marcuzzi and colleagues in 2013 specifically for quantitative sensory testing studies This method assesses 1 whether the sample was clearly described 2 whether the sample is representative of the population 3 whether the somatosensory assessment methods are standardized validated and well described 4 adequate blinding if relevant and 5 whether potential confounders were taken into account
Strategy for data synthesis
A quantitative synthesis using aggregate data of the data is planned The standardized mean difference with a 95 confidence interval will be calculated for all included studies for which sufficient data are available Both between and within subject designs will be included sensitivity analyses will be conducted to test for a difference in design type withinbetween If significant differences are detected design type will be included in the analyses as a moderator variable Subsequently the pooled effects for each of the experimental induction will be analyzed using a random-effects model The effects of experimental inductions will also be compared between placebo and nocebo effects If sufficient data are available the effects of the experimental inductions will be compared between different somatosensory sensations see below Where statistical pooling is not possible the findings of the systematic review will be presented in narrative form Heterogeneity will be assessed with the I2 statistic by visual inspection of the forest plots and by subset analyses see below The presence of publication bias will also be assessed eg via inspection of a funnel plot
1 What is the average magnitude of placebo or nocebo effects on pain and on itch across included studies
2 Across studies that tested multiple learning processes for placebo and nocebo effects on pain is the magnitude of a placebo or nocebo effect on pain different based on the learning process used to induce the effect
3 Does the magnitude of placebo or nocebo effects differ between the sensations of pain and itch
4 Are nocebo effects on pain and itch stronger than placebo effects on pain and itch as measured by their relative magnitude
Dependent upon search results the researchers intend to answer questions 1 and 2 with meta-analysis and questions 3 and 4 with systematic review
Search Strategy
PubMed PsycINFO EMBASE and the Cochrane CENTRAL Methodology Library will be searched Languages are restricted to English Dutch and German Publication period is not restricted Searches were initially conducted on March 18th 2019 The detailed key-worded search strategy will not be made publicly available until this review is complete
Condition or domain being studied
Experimental induction of placebo or nocebo effects on somatosensory sensations ie pain andor itch For the purposes of in- and exclusion studies are considered to have induced a placebo or nocebo effect if the supposed administration of an inert treatment is paired with a given learning process attempt to induce positive or negative outcome-effects
Participantspopulation
Healthy adult human volunteers Patient samples will not be included to improve homogeneity of the results
Data extraction
Titles and abstracts of articles retrieved using the search strategy and those from additional sources will be screened by two independent reviewers to identify studies that potentially meet the inclusion criteria outlined above The full text of these articles and articles about which doubts exist based on the title andor abstract will be retrieved and assessed for eligibility by two independent reviewers Full texts that are considered to be possibly eligible for inclusion or about which doubts exist will also be assessed for eligibility by a third reviewer Two independent reviewers will use a standardized form to extract data from the included studies to derive study characteristics assess study quality and for data analysis Extracted information will include details of the intervention control condition study population sensation type and how sensations were measured eg self-report type of experimental induction ie learning method used type of expectancy ie placebo or nocebo information for quality assessment and outcome data for meta-analysis eg sample size mean and standard deviation Doubts regarding data-extraction will be resolved through discussion with a second review author Missing data will be requested from the study authors
Risk of bias assessment
Risk of bias will be assessed using the method developed by Marcuzzi and colleagues in 2013 specifically for quantitative sensory testing studies This method assesses 1 whether the sample was clearly described 2 whether the sample is representative of the population 3 whether the somatosensory assessment methods are standardized validated and well described 4 adequate blinding if relevant and 5 whether potential confounders were taken into account
Strategy for data synthesis
A quantitative synthesis using aggregate data of the data is planned The standardized mean difference with a 95 confidence interval will be calculated for all included studies for which sufficient data are available Both between and within subject designs will be included sensitivity analyses will be conducted to test for a difference in design type withinbetween If significant differences are detected design type will be included in the analyses as a moderator variable Subsequently the pooled effects for each of the experimental induction will be analyzed using a random-effects model The effects of experimental inductions will also be compared between placebo and nocebo effects If sufficient data are available the effects of the experimental inductions will be compared between different somatosensory sensations see below Where statistical pooling is not possible the findings of the systematic review will be presented in narrative form Heterogeneity will be assessed with the I2 statistic by visual inspection of the forest plots and by subset analyses see below The presence of publication bias will also be assessed eg via inspection of a funnel plot
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
False
Is a FDA Regulated Device?:
False
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None