We updated the existing systematic reviews only if the most
recent review on a specific intervention was conducted before
December 2011. For updating the existing reviews, we adopted
the same methodology and search strategy mentioned in the
existing review to update the search and find all the relevant
studies after the last search date of the existing review. After
retrieval of the full texts of all the articles that met the inclusion/
exclusion criteria, data from each study were abstracted
independently and in duplicate into a standardized form.
Information was extracted on study design, geographical
setting, intervention type and description, mode of delivery, and
outcomes assessed. We then updated the estimates of reported
outcomes by pooling the evidence from the new studies identified
in the updated search and reported new effect size for the
outcomes of interest with 95% CIs. We then assessed and
reported the quality of included reviews using the 11-point
assessment of the methodological quality of systematic
reviews criteria [28].