Background
Introduction
Objectives
Methods/Design
Phase I: Systematic review to identify eligible papers
Trial eligibility criteria
Methodology
Adequate allocation concealment | Inadequate allocation concealment |
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Centralized randomization procedures in which the persons including a patient contact the randomization center or a person otherwise not involved in the trial who registers the patient as included in the trial and only then provides the allocation information for this patient | An open random allocation schedule, that is, where all future allocations can be read by an investigator |
Any computerized system that ensures, by password protection or other computer security procedures, conditions 1 and 2 described in the text | Envelopes, if clear details of the procedures used to avoid allocation becoming unconcealed are inadequate, or unclear |
Use of consecutively numbered, opaque sealed envelopes containing the allocation information kept by a person otherwise not involved in the study with envelopes opened only after registration of an included patient | Assignment envelopes were used without appropriate safeguards (for example if envelopes were unsealed or non-opaque or not sequentially numbered) |
Alternation, rotation, day of the week | |
Date of birth, or medical record number | |
Blocked randomization with block size known to the person including the patient | |
An unspecified method, for example, if the report states only that "patients were randomized" without giving details of the exact procedures used, and no further information is obtained from the authors. |
Patients
Interventions
Controls
Outcomes
Trial size
Language
Search strategy for identification of studies
Inclusion of studies
Quality assessment
Methodological quality
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A: Low likelihood of bias: EITHER the adequacy of blinding was checked by direct questioning of patients, for example, with a credibility questionnaire, and no important differences were found between groups OR a blinding method (e.g. the Streitberger sham device) was used that had previously been validated as able to maintain blinding.
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C: High likelihood of bias: Clear reasons to believe that blinding was broken, for example, differential responses to a credibility questionnaire or obviously non-credible sham technique
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B: Intermediate likelihood of bias: A trial that does not meet the criteria for either a grade of A or C.