The contribution of databases to the results of systematic reviews: a cross-sectional study

Table 6 Impact of selective searching on results of meta-analysis from developmental, psychosocial and learning problems

		Original meta-analysis				Meta-analysis based on studies identified by selective search
Case	Summary measure	Number of trials	Effect size	Lower CI	Upper CI	Number of trials	Effect size	Lower CI	Upper CI	% of trials identified	% change in effect size
Medline + PsycInfo (changes in 15 of 33 meta-analyses)
1^{a, b}	MD	5	−1.25	−4.56	2.06	3	−1.48	−5.96	3	60	15.5
2^a	SMD	10	−0.24	−0.35	−0.13	8	−0.25	−0.38	−0.11	80	4.0
3^a	MD	5	0.02	−0.09	0.12	4	0	−0.11	0.11	80	NA
4	SMD	10	0.47	0.06	0.88	9	0.49	0.04	0.93	90	4.1
5^a	SMD	2	0.5	0.22	0.79	1	0.48	0.18	0.77	50	4.0
6^a	RR	10	0.51	0.37	0.72	8	0.48	0.34	0.69	80	5.9
7^a	MH OR	4	0.61	0.27	1.39	3	0.48	0.14	1.6	75	21.3
8^a	RR	6	0.69	0.60	0.78	5	0.66	0.59	0.74	83	4.3
9^{a, b}	RR	10	0.73	0.56	0.95	7	0.65	0.47	0.9	70	11.0
10^a	RR	17	0.76	0.69	0.83	16	0.75	0.68	0.82	94	1.3
11^a	MH OR	4	0.87	0.61	1.25	3	0.78	0.52	1.17	75	10.3
12^a	Other	2	1	0.59	1.71	0	-	-	-	0	-
13^{a, b}	MH OR	2	1.05	0.90	1.23	1	1.09	0.85	1.41	50	3.7
14^a	MH OR	7	1.68	1.20	2.36	2	1.78	0.93	3.41	29	5.6
15	MD	4	14.37	12.30	16.44	3	12.33	10.14	14.51	75	14.2
Medline + PsycInfo + ERIC (changes in 13 of 33 meta-analyses; data below show cases where results were different from Medline + PsycInfo results above^b)
1	MD	5	−1.25	−4.56	2.06	4	−0.96	−5.07	3.15	0.8	23.2
9	RR	10	0.73	0.56	0.95	9	0.69	0.52	0.92	0.9	5.5
13	MH OR	2	1.05	0.90	1.23	2	1.09	0.91	1.31	1	3.7

CI confidence interval, MD mean difference, MH OR Mantel Haenszel odds ratio, NA not applicable, RR risk ratio, SMD standardized mean difference
^acases where results also changed for Medline + PsycInfo + ERIC; ^bcases where results were different between Medline + PsycInfo and Medline + PsycInfo + ERIC

ISSN: 1471-2288