Search methods for identification of studies

We will search the following databases without language restrictions.

The Cochrane Central Register of Controlled Trials (CENTRAL) (via the Cochrane Library).

MEDLINE (via Ovid).

Embase.com.

CINAHL (via EBSCOhost).

Science Citation Index (Web of Science).

Latin America and Caribbean Health Sciences (LILACS).

Medical subject headings (MeSH) or equivalent and text word terms will be used. Where appropriate, MeSH terms will be exploded. We will apply a modified version of the Cochrane filter for the identification of RCTs, as published in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Searches will be tailored to individual databases. The search strategy for MEDLINE is in Appendix 1.

We will search the metaRegister of controlled trials (mRCT) (www.controlled‐trials.com/mrct), clinicaltrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (apps.who.int/trialsearch/) for ongoing trials. In addition, reference lists of reviews and retrieved articles will be checked for additional studies and citation searches will be performed on key articles. We will contact experts in the field for unpublished and ongoing trials. We will contact authors where necessary for additional information.