Blinding and sham control methods in trials of physical, psychological, and self-management interventions for pain (article II): a meta-analysis relating methods to trial results
File(s)
Author(s)
Hohenschurz-Schmidt, David
Draper-Rodi, Dr Jerry
Vase, Prof Lene
Scott, Dr Whitney
McGregor, Prof Alison
Type
Journal Article
Abstract
Sham interventions in randomised clinical trials (RCTs) of physical, psychological, and self-management (PPS) therapies for pain are highly variable in design and thought to contribute to poor internal validity. It has, however, not been formally tested whether the extent to which sham controls resemble the treatment under investigation consistently affects trial outcomes, such as effect sizes, differential attrition, participant expectancy, and blinding effectiveness.
Placebo or sham-controlled RCTs of PPS interventions of clinical pain populations were searched in twelve databases. The similarity of control interventions to the experimental treatment was rated across 25 features. Meta-regression analyses assessed putative links between employed control interventions, observed effect sizes in pain-related outcomes, attrition, and blinding success.
The sample included 198 unique control interventions, dominated by manual therapy and chronic musculoskeletal pain research. Meta-analyses indicated small to moderate benefit of active treatments over control interventions, across subgroups of manual therapies, exercise, and rehabilitation, and psychological intervention trials. Multiple meta-regression modelling demonstrated that similarity between sham control and tested interventions predicted variability in pain-related outcomes, attrition, and blinding effectiveness. Influential were differences relating to the extent of intervention exposure, participant experience, and treatment environments.
The results support the supposed link between blinding methods and effect sizes, based on a large and systematically sourced overview of methods. Challenges to effective blinding are, however, complex, and often difficult to discern from trial reports. Nonetheless, these insights have the potential to change trial design, conduct, and reporting and will inform guideline development.
Placebo or sham-controlled RCTs of PPS interventions of clinical pain populations were searched in twelve databases. The similarity of control interventions to the experimental treatment was rated across 25 features. Meta-regression analyses assessed putative links between employed control interventions, observed effect sizes in pain-related outcomes, attrition, and blinding success.
The sample included 198 unique control interventions, dominated by manual therapy and chronic musculoskeletal pain research. Meta-analyses indicated small to moderate benefit of active treatments over control interventions, across subgroups of manual therapies, exercise, and rehabilitation, and psychological intervention trials. Multiple meta-regression modelling demonstrated that similarity between sham control and tested interventions predicted variability in pain-related outcomes, attrition, and blinding effectiveness. Influential were differences relating to the extent of intervention exposure, participant experience, and treatment environments.
The results support the supposed link between blinding methods and effect sizes, based on a large and systematically sourced overview of methods. Challenges to effective blinding are, however, complex, and often difficult to discern from trial reports. Nonetheless, these insights have the potential to change trial design, conduct, and reporting and will inform guideline development.
Date Issued
2023-03-01
Date Acceptance
2022-07-01
Citation
Pain, 2023, 164 (3), pp.509-533
ISSN
0304-3959
Publisher
Ovid Technologies (Wolters Kluwer Health)
Start Page
509
End Page
533
Journal / Book Title
Pain
Volume
164
Issue
3
Copyright Statement
© 2022 International Association for the Study of Pain
Identifier
https://journals.lww.com/pain/Abstract/9900/Blinding_and_sham_control_methods_in_trials_of.131.aspx
Publication Status
Published
Date Publish Online
2022-07-11