Assessment of Study Quality and Strength of Evidence
Each trial was assessed for risk for bias on the basis of
the method proposed by others (19). Domains of quality
included adequate allocation concealment, indicated by
central allocation, including telephone, Web-based and
pharmacy-controlled randomization or use of sequentially
numbered, opaque, sealed envelopes; blinding of key study
personnel (for this intervention, only outcome assessment
could be blinded); analysis by intention-to-treat; and reporting
of number of patients who withdrew or dropped
out (patients who withdrew from further participation or
follow-up or whose whereabouts were unknown), by group
assignment. We also noted whether the trial was funded by
industry.
We evaluated the overall strength of evidence for each