From: The contribution of databases to the results of systematic reviews: a cross-sectional study
 |  | 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 + BIOSIS (changes in 17 of 57 meta-analyses) | |||||||||||
1a | MD | 5 | −21.29 | −29.59 | −13 | 1 | −22.9 | −41.34 | −4.46 | 20 | 7.0 |
2a | MD | 35 | −1.24 | −1.54 | −0.94 | 26 | −1.42 | −1.77 | −1.06 | 74 | 12.7 |
3a | MD | 24 | −0.45 | −0.96 | 0.05 | 19 | −0.25 | −0.9 | 0.39 | 79 | 44.7 |
4a | RD | 2 | −0.13 | −0.21 | −0.05 | 1 | −0.16 | −0.26 | −0.05 | 50 | 18.8 |
5a | RD | 3 | −0.05 | −0.12 | 0.02 | 1 | −0.04 | −0.14 | 0.06 | 33 | 20.0 |
6 | MH OR | 6 | 0.27 | 0.15 | 0.50 | 3 | 0.19 | 0.08 | 0.46 | 50 | 29.6 |
7a, b | MH OR | 7 | 0.35 | 0.12 | 1.01 | 6 | 0.26 | 0.12 | 0.6 | 86 | 25.7 |
8a | RR | 2 | 0.48 | 0.17 | 1.34 | 0 | - | - | - | 0 | - |
9a, b | SMD | 8 | 0.49 | 0.16 | 0.81 | 6 | 0.51 | 0.1 | 0.93 | 75 | 3.9 |
10 | MD | 3 | 0.5 | 0.10 | 0.90 | 2 | 0.43 | −0.01 | 0.87 | 67 | 14.0 |
11 | RR | 6 | 0.67 | 0.50 | 0.89 | 5 | 0.75 | 0.55 | 1.04 | 83 | 10.7 |
12 | RR | 25 | 0.9 | 0.80 | 1.01 | 22 | 0.91 | 0.8 | 1.02 | 88 | 1.1 |
13a | RR | 6 | 0.95 | 0.59 | 1.51 | 3 | 0.96 | 0.82 | 1.11 | 50 | 1.0 |
14a, b | RR | 29 | 0.95 | 0.92 | 0.98 | 19 | 0.96 | 0.94 | 0.99 | 66 | 1.0 |
15a, b | RR | 15 | 1.09 | 0.64 | 1.85 | 13 | 0.9 | 0.54 | 1.49 | 87 | 17.4 |
16a | RR | 2 | 1.32 | 0.87 | 2.00 | 0 | - | - | - | 0 | - |
17 | RR | 15 | 1.82 | 0.98 | 3.38 | 14 | 1.97 | 1.06 | 3.64 | 93 | 7.6 |
Medline + Embase (changes in 12 of 57 meta-analyses; data below show cases where results were different from Medline + BIOSIS results aboveb) | |||||||||||
7 | MH OR | 7 | 0.35 | 0.12 | 1.01 | 4 | 0.14 | 0.04 | 0.53 | 57 | 60.0 |
9 | SMD | 8 | 0.49 | 0.16 | 0.81 | 6 | 0.4 | 0.07 | 0.73 | 75 | 18.4 |
14 | RR | 29 | 0.95 | 0.92 | 0.98 | 19 | 0.97 | 0.94 | 1 | 66 | 2.1 |
15 | RR | 15 | 1.09 | 0.64 | 1.85 | 14 | 0.96 | 0.58 | 1.57 | 93 | 11.9 |