Table 1.

List of databases and search periods included in systematic search.

Databases	Search dates
EMBASE   MEDLINE (via PubMed)   CENTRAL	Until 30 September 2013
LILACS and IBECS   African Index Medicus, Index Medicus for Eastern and Mediterranean   Region, and Index Medicus for South-East Asia Region and The Western Pacific   Region Index Medicus   African Journals Online   IndMed (India)   PakMediNet (Pakistan)   Türk Tip Veri Tabani (Turkey)   Krack (Croatia)   SID and IrMedex (Iran)   KoreaMed (Korea)	Conducted between 26 and 30 September 2013
ICHUSHI-Web (Japan)	Until 22 April 2013
Wanfang, Cqvip, and CNKI (China)	Until 16 April 2013