Table 2 Reasons for rating randomised trials as high ROB for sequence generation in Cochrane reviews
From: Risk of bias assessment of sequence generation: a study of 100 systematic reviews of trials
Review | Number of randomised trials rated as high ROB for sequence generation (% of total included randomised trials) | Justification for high ROB for sequence generation (as stated by the review authors) |
|---|---|---|
Lund et al. [13] | 3 (75%) | Altinli 2007: “Participants were randomised into 2 groups, according to the day the participant was first seen in the clinic (odd and even days).” Sozen 2011a: “The participants were randomised into 2 groups—drained and fibrin sealant—according to the admission protocol number. Details of this protocol number unclear.” Sozen 2011b: “The participants were randomised into two groups, drained and non-drained, according to the admission protocol number. Nature of this protocol number unclear.” |
Cheng et al. [9] | 1 (16.7%) | Randomisation may have not been executed properly as there was a large difference in the number of participants in each arm; the acupuncture arm had 25/109 (40%) more participants than the control group. A random number table was used to generate sequence. Odd numbers were allocated to treatment group, even numbers were allocated to control group. |
Chauhan et al. [14] | 1 (2.7%) | Participants were randomised to 2 groups according to their order of presentation at the outpatient clinic. |
McCaughan et al. [15] | 1 (16.7%) | The randomisation protocol was compromised by selecting patients serially as they registered. |
Menting et al. [8] | 2 (6.9%) | Czibik-stable 2008 and Czibik-unstable 2008: “Randomisation not reported” |