Quality assessment of studies
Two authors (A.S. and E.C.) assessed study quality and risk of bias
independently using a standardised Excel form. Randomised trials were
analysed using the Cochrane Collaboration’s tool14 for
assessing risk of bias. Case-control and cohort studies were analysed
using the Newcastle-Ottawa scale15 for assessing the
quality of non-randomised studies. An adaptation of the Murad
tool16 was used for case series.