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 + Embase (changes in 9 of 31 meta-analyses) | |||||||||||
1a, b | MD | 35 | −24.76 | −33.61 | −15.91 | 30 | −22.22 | −31.85 | −12.6 | 86 | 10.3 |
2a, b | RR | 5 | 0.41 | 0.11 | 1.64 | 3 | NE | - | - | 60 | - |
3 | RR | 4 | 0.48 | 0.35 | 0.65 | 3 | 0.57 | 0.29 | 1.09 | 75 | 15.8 |
4a, b | RR | 21 | 0.53 | 0.49 | 0.57 | 16 | 0.51 | 0.46 | 0.56 | 76 | 3.8 |
5a, b | MH OR | 11 | 0.59 | 0.45 | 0.79 | 7 | 0.61 | 0.41 | 0.89 | 64 | 3.3 |
6a | RR | 3 | 0.62 | 0.19 | 2.04 | 2 | 0.56 | 0.14 | 2.14 | 67 | 9.7 |
7a, b | MH OR | 10 | 0.68 | 0.49 | 0.95 | 8 | 0.59 | 0.41 | 0.86 | 80 | 13.2 |
8a | RR | 8 | 0.71 | 0.62 | 0.80 | 6 | 0.72 | 0.64 | 0.82 | 75 | 1.4 |
9a | RR | 13 | 0.99 | 0.90 | 1.09 | 11 | 0.95 | 0.86 | 1.05 | 85 | 4.0 |
Medline + BIOSIS (changes in 8 of 31 meta-analyses; data below show cases where results were different from Medline + Embase results aboveb) | |||||||||||
1 | MD | 35 | −24.76 | −33.61 | −15.91 | 29 | −23.18 | −32.94 | −13.42 | 83 | 6.4 |
2 | RR | 5 | 0.41 | 0.11 | 1.64 | 3 | NE | - | - | 60 | - |
4 | RR | 21 | 0.53 | 0.49 | 0.57 | 17 | 0.49 | 0.44 | 0.54 | 81 | 7.5 |
5 | MH OR | 11 | 0.59 | 0.45 | 0.79 | 8 | 0.64 | 0.48 | 0.87 | 73 | 7.8 |
7 | MH OR | 10 | 0.68 | 0.49 | 0.95 | 8 | 0.54 | 0.34 | 0.86 | 80 | 20.6 |