Abstract
After publication of the article [1], it has been brought to our attention that the original version of this Article contained a typo in the 3rd paragraph of the section 'Review process and data extraction'. It concerns the equation published as "Var(lnRR) = Var(lnR1 + lnR0)". On the right part, the "+" within the parenthesis should be "-", as defined and derived from the left part. As a result, Var(lnRR) = Var(lnR1 + lnR0) should be revised to Var(lnRR) = Var(lnR1 - lnR0).