| Database | Dates searched | Frequency of search |
| CENTRAL (via the Cochrane Register of Studies (CRS)) | From inception | Monthly |
| MEDLINE (Ovid SP) | 1946 onwards | Weekly |
| EMBASE (Ovid SP) | 1974 onwards | Weekly |
| PsycINFO (Ovid SP) | 1967 onwards | Monthly |
| CINAHL (EBSCO) | 1937 onwards | Monthly |
| AMED (EBSCO) | From inception | Monthly |
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