Table 1.

Glossary of terms and explanation of fundamental concepts.

Term	Definition
Bias	A systematic distortion, due to a design problem, an interfering factor, or a judgement, that can affect the conception, design, or conduct of a study, or the collection, analysis, interpretation, presentation, or discussion of outcome data, causing erroneous overestimation or underestimation of the probable size of an effect or association
Allocation concealment	Allocation to the treatment or control groups done in a way that prevents preferential allocation of patients to a particular group
Blinding of patients	Concealment from patients of the treatment (active or control) to which they have been allocated. Blinding minimises many types of bias, including confounding, reporting bias, assessment bias, and bias caused by interactions with carers or clinical staff; it minimises dissatisfaction with the treatment allocation and the subsequent tendency to seek cotreatment; and it minimises drop-outs
Blinding of assessors	Concealment of the treatment allocation from those assessing and analysing the results. Assessor blinding may not be required if the outcomes are objective (eg, mortality, survival time, or laboratory tests) rather than subjective (eg, functional measures, quality-of-life scores, or other self-reported measures, including pain)
Blinding of providers	Concealment of the group allocation from those administering the treatment. In drug trials, this is typically done by overencapsulating or repackaging the medicines, but it is often challenging in nonpharmacological trials
Blinding—others	Blinding of other people involved in the trial. This prevents unintentional unblinding by revealing treatment allocation
Harm(s)	Adverse effects or adverse reactions, including nocebo effects; also delays to the introduction of effective treatment, propagation of harmful/unhelpful interventions/recommendations; generation of vested interests of providers into ineffective therapies; time and resources wasted on ineffective therapies
Nonpharmacological therapies	Nonpharmacological interventions are procedures that do not involve the use of a pharmacological agent; they include psychological and cognitive-behavioural approaches, exercise and rehabilitation, manual therapies, acupuncture, mind–body techniques such as yoga, devices such as ultrasound and light therapy, electrical therapies, education, and surgery; nutritional interventions are typically not included
Placebo control	A treatment or procedure ie, indistinguishable from the tested treatment, resembling it in all aspects but omitting the therapeutic components of the test treatment that are to be studied in the trial. In the case of surgery placebo control procedure may include anaesthesia/analgesia, standard care, and cointerventions
Randomisation	Random allocation to test and control group, which controls for small baseline differences between the groups and natural fluctuation of the studied condition
Test treatment	The intervention, or therapy the trial sets out to investigate
Treatment effect	The effect produced by the therapeutically active component of an intervention
Treatment provider	A person providing test and/or control treatment as part of a trial