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.

ABSTRACT: Sham interventions in randomized clinical trials (RCTs) of physical, psychological, and self-management (PPS) therapies for pain are highly variable in design and believed to contribute to poor internal validity. However, it has 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 12 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 benefits 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 variables 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. However, challenges to effective blinding are 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.

Blinding and sham control methods in trials of physical, psychological, and self-management interventions for pain (article I): a systematic review and description of methods.

ABSTRACT: Blinding is challenging in randomised controlled trials of physical, psychological, and self-management therapies for pain, mainly because of their complex and participatory nature. To develop standards for the design, implementation, and reporting of control interventions in efficacy and mechanistic trials, a systematic overview of currently used sham interventions and other blinding methods was required. Twelve databases were searched for placebo or sham-controlled randomised clinical trials of physical, psychological, and self-management treatments in a clinical pain population. Screening and data extraction were performed in duplicate, and trial features, description of control methods, and their similarity to the active intervention under investigation were extracted (protocol registration ID: CRD42020206590). The review included 198 unique control interventions, published between 2008 and December 2021. Most trials studied people with chronic pain, and more than half were manual therapy trials. The described control interventions ranged from clearly modelled based on the active treatment to largely dissimilar control interventions. Similarity between control and active interventions was more frequent for certain aspects (eg, duration and frequency of treatments) than others (eg, physical treatment procedures and patient sensory experiences). We also provide an overview of additional, potentially useful methods to enhance blinding, as well as the reporting of processes involved in developing control interventions. A comprehensive picture of prevalent blinding methods is provided, including a detailed assessment of the resemblance between active and control interventions. These findings can inform future developments of control interventions in efficacy and mechanistic trials and best-practice recommendations.

Interoceptive Sensibility in Professional Dancers Living With or Without Pain: A Cross-Sectional Study.

BACKGROUND: There is a growing body of literature investigating the use of manual therapy to modulate pain through interoceptive pathways, but studies amongst the dancer population are lacking. OBJECTIVES: To investigate self-reported measures of interoceptive sensibility (IAs) in professional dancers living with or without pain, and to explore associations between IAs and confounding variables (e.g., psychopathologies). METHODS: 128 UK-based adult professional dancers, from any dance style, living with or without pain, completed a cross-sectional online survey. Pain status was self-reported and participants were assigned in three study groups for analyses (pain-free n=26, acute n=30, and chronic pain n=72). The Multidimensional Assessment of Interoceptive Awareness, ver. 2 (MAIA-2) was used to measure IAs. An additional questionnaire was used to collect demographic and putative confounding data (i.e., age, sex, BMI, dance style, employment status, level of experience, mindfulness experience, pain history and management such as manual therapy use, eating disorders, depression, and anxiety). RESULTS: No overall significant difference was found in IAs between groups (pain-free-control, acute, and chronic pain). A one-way ANOVA showed significantly lower scores for the MAIA-2 Non-Distracting subscale in dancers living with pain (acute or chronic) compared to the pain-free-control group. Moreover, an association between manual therapy use and some subscales of the MAIA-2 was found in the population. CONCLUSIONS: Results should be interpreted with caution, as major confounding variables (i.e., psychopathologies) could not be excluded from the analysis due to their high prevalence in the sample. Positive associations between adaptive subscales of the MAIA-2 and the use of manual therapy support a need for further research investigating potential clinical applications using interoceptive pathways in the specialised management of pain in dancers.