| Boylan 2004 | Some concerns | No information on allocation concealment, but baseline characteristics do not show any differences between the two groups. | Low risk of bias | Though there is no information on whether the allocation was blinded to participants or treating physicians, there were no significant deviations outside the trial context. Analysis was also as randomised. | Low risk of bias | Data reasonably complete for all the included patients | Low risk of bias | Being an objective outcome, it is unlikely that assessment of the outcome would be influenced by knowledge of allocation group | Some concerns | A trial protocol is not available for assessment | High risk of bias | Some concerns in more than one domain |