Table 2

Characteristics of Studies Reporting on Emergency Room Visits.*

Study

    Intervention Group

    Control Group

Duration (Months)

Standardized Effect Size**

N

Mean ± SD

Rate

N

Mean ± SD

Rate


Alexander

11

0.60 ± 0.90

0.05

10

2.40 ± 2.10

0.20

12

-1.09

Christiansen

27

0.30 ± 1.20

0.03

15

0.20 ± 0.43

0.02

12

0.10

Clark

159

1.72 ± 4.20

0.14

73

2.49 ± 6.26

0.21

12

-0.16

Fireman

13

0.08 ± 1.14

0.01

13

1.00 ± 1.14

0.08

12

-0.78

Hughes

44

0.45 ± 1.05

0.04

45

0.60 ± 1.05

0.05

12

-0.14

Lewis

48

2.30 ± 2.98

0.19

28

3.71 ± 2.98

0.31

12

-0.47

McNabb

7

1.90 ± 4.72

0.16

7

7.40 ± 4.72

0.62

12

-1.09

Persaud

18

0.27 ± 0.57

0.05

18

1.00 ± 1.20

0.20

5

-0.76

Ronchetti

114

0.07 ± 0.32

0.01

95

0.23 ± 0.78

0.02

12

-0.28

Shields

101

0.54 ± 1.68

0.05

104

0.38 ± 1.68

0.03

12

0.09

Talabere

25

0.44 ± 0.77

0.15

25

1.08 ± 1.32

0.36

3

-0.58

Toelle

63

1.51 ± 2.31

0.25

51

1.67 ± 2.40

0.28

6

-0.07


* N refers to the sample size, Mean ± SD refers to the mean number of events ± standard deviation, and rate refers to the total events per person-month. ** Standardized effect size was calculated for each study by subtracting control group mean from intervention group mean and dividing by the pooled SD.

Guevara et al. BMC Medical Research Methodology 2004 4:17   doi:10.1186/1471-2288-4-17

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