Background: currently, there is a lack of agreement regarding the construction of control interventions for randomised clinical trials in psychiatric research. Control interventions provide a frame of reference for the experimental interventions they are compared to and enable estimations of the benefits and harms of a given treatment. However, information about control interventions are often under-reported in psychiatric trial reports and subject to substantial methodological heterogeneity. This systematic review investigates the effects and adverse events of the most commonly used control interventions in psychiatric research. These include psychological, pharmacological and physical placebos, usual care, wait-list and no-treatment controls.
Objectives: we will address three research questions: what are the beneficial effects and adverse events of
1) different placebo interventions versus no-treatment or wait-list;
2) usual care versus no-treatment or wait-list; and
3) wait-list versus no-treatment?
Methods: the project is a Cochrane Systematic Review investigating control interventions in randomised trials for all mental health disorders. Participants were required to have a formal diagnosis of a mental health disorder according to Diagnostic and Statistical Manual of Mental Disorders (DSM) or the International Classification of Diseases and Related Health Problems (ICD). We included studies that compared the different kinds of placebo, usual care to a pooled intervention of wait-list and no treatment. When comparing wait-list to no treatment we separated them.
Results: we screened a total number of 52,429 reports from 11 different databases and six trials registries. The screening process is still ongoing, but we will include approximately 100 trials with different control interventions. Preliminary results from the review are expected to be done in the summer of 2019, and will be presented at the Cochrane Colloquium.
Conclusions: we are currently extracting data from the included studies and the final results will be presented at the Colloquium.
Patient or healthcare consumer involvement: most placebo research has been done on healthy participants, limiting conclusions to be drawn on the clinical population. This systematic review is therefore of great importance to establish the placebo effect and usual care effect in relation to nothing with patients with a mental health disorder. By identifying novel solutions on how to develop and properly construct these interventions, patients and consumers receiving the best available treatments for mental health issues will benefit.