Table 2.
Sources of primary studies most frequently searched in the included systematic reviews (n = 301).
| No. | Databases | n (%) |
|---|---|---|
| 1 | PubMed | 181 (60.1) |
| 2 | Medline | 161 (53.5) |
| 3 | Embase | 159 (52.8) |
| 4 | Web of science | 126 (41.9) |
| 5 | PsycInfo | 94 (31.2) |
| 6 | CINAHL (Cumulative Index to Nursing and Allied Health Literature) | 93 (30.9) |
| 7 | Scopus | 77 (25.6) |
| 8 | Cochrane library | 64 (21.3) |
| 9 | Science direct | 22 (7.3) |
| 10 | CNKI (Chinese National Knowledge Infrastructure) | 12 (4.0) |
| 11 | SPORTDiscus | 12 (4.0) |
| 12 | ERIC (Educational Resources Information Center) | 11 (3.6) |
| 13 | LILACS (Latin American and Caribbean Health Sciences Literature) | 11 (3.6) |
| 14 | EBSCO | 10 (3.3) |
| 15 | Global health | 10 (3.3) |
| No. | Websites | n (%) |
| 1 | WHO (World Health Organization) | 5 (1.7) |
| 2 | NICE (National Institute for Health and Care Excellence) | 3 (1.0) |
| 3 | UNICEF (United Nations Children's Fund) | 3 (1.0) |
| 4 | US-CDC (United States Centers for Disease Control and Prevention) | 3 (1.0) |
| 5 | ECDC (European Center for Disease Prevention and Control) | 2 (0.7) |
| 6 | ICRC (International Committee of the Red Cross) | 2 (0.7) |
| 7 | IOM (International Organization of Migration) | 2 (0.7) |
| 8 | IRC (International Rescue Committee) | 2 (0.7) |
| 9 | MSF (Médecins Sans Frontières) | 2 (0.7) |
| 10 | ReliefWeb | 2 (0.7) |
| 11 | UNAIDS (Joint United Nations Programme on HIV/AIDS) | 2 (0.7) |
| 12 | UNHCR (United Nations High Commissioner for Refugees) | 2 (0.7) |
| No. | Registration platforms | n (%) |
| 1 | CENTRAL (Cochrane Central Register of Controlled Trials) | 28 (9.3) |
| 2 | ClinicalTrials.gov | 13 (4.3) |
| 3 | ICTRP (WHO International Clinical Trials Registry Platform) | 8 (2.6) |
| 4 | Australian New Zealand Clinical Trials Registry | 2 (0.7) |
| No. | Other sources | n (%) |
| 1 | Scanning the reference lists and other relevant review articles | 180 (60.0) |
| 2 | Google Scholar | 63 (20.9) |
| 3 | 15 (5.0) | |
| 4 | Experts' consultation | 12 (4.0) |
| 5 | Conference proceedings | 11 (3.6) |
| 6 | Contact the authors | 10 (3.3) |
| 7 | Specialist journals | 7 (2.3) |
| 8 | Other handing searching methods | 23 (7.6) |
Some researchers regard PubMed as a database rather than a search platform. And we only extracted data that were reported in each SR.