Effectiveness of different databases in identifying studies for systematic reviews: experience from the WHO systematic review of maternal morbidity and mortality

Table 1 Results of the various types of searches

Source	Number identified	Number included	Number unique included*	Sensitivity (%)	Precision (%)
MEDLINE	38986	1590	400	61.6	4.1
Popline	3255	297	91	11.5	9.1
EMBASE	23133	1135	154	43.9	4.9
CINAHL	9090	263	9	10.2	2.9
CAB Abstracts	4317	190	19	7.4	4.4
Econlit	188	4	1	0.2	2.1
SocioFile	1618	32	8	1.2	2.0
LILACS	1456	137	117	5.3	9.4
BIOSIS	3313	436	21	16.9	13.2
PAIS International	705	21	3	0.8	3.0
IMEMR	109	11	5	0.4	10.1
All Electronic databases**	64098	2093	NA	81.1	3.3
Other ^§	487	487	487	18.9	NA
*TOTAL* ^±	*64585*	*2580*	*2580*	NA	*4.0*

* Refers to the number of citations that were exclusively identified by each database.
** Refers to all citations identified through the electronic databases above after duplicate entries are removed.
^§ Includes hand searching, contacting experts, conference proceedings, reference lists, library collections of journals, and databases in developing countries.
^± Refers to all citations identified through all methods after duplicate entries are removed. NA: Non-applicable

ISSN: 1471-2288