Table 3 Major points in 57 methods publications addressing allocation bias directionality and mechanisms
From: Mechanisms and direction of allocation bias in randomised clinical trials
Direction of bias | Na (%) |
|---|---|
Studies explicitly commenting on direction of bias | 27 of 57 (47 %) |
Studies commenting only on exaggeration of treatment effect | 16 (28 %) |
Studies commenting on possible bias in both directions | 11 (19 %) |
Studies not explicitly commenting on direction of bias | 30 of 57 (53) |
Mechanisms of bias | |
Allocation concealment protects against allocation bias | 53 of 57 (93 %) |
Preferential allocation of patients may lead to bias. | 32 of 57 (56 %) |
Allocation bias is possible in trials with restricted randomisationb, if upcoming assignments can be guessed. | 11 of 57 (19 %) |