Table 3

Factors explaining the mean (±standard deviation) of the standardized differences in superiority and noninferiority trials and single p-value after adjustment on the type of trial.

Superiority trials

Noninferiority trials

P-value*


Standardized

difference

No.

P-value

Standardized

difference

No.

P-value


Year of publication

2004-2006

0.46 (0.23)

59

0.42

0.28 (0.13)

59

0.40

0.72

2007-2009

0.42 (0.30)

41

-

0.30 (0.12)

41

-

-


Medical context

0.38

0.001

0.006

Cardiovascular

0.36 (0.22)

14

0.18 (0.09)

19

Infectious diseases

0.51 (0.11)

3

0.33 (0.08)

23

Oncology

0.44 (0.23)

6

0.26 (0.008)

10

Other

0.47 (0.27)

77

0.31 (0.14)

48


Pharmacological trial

Yes

0.44 (0.28)

54

0.76

0.29 (0.12)

73

0.99

0.77

No (other area)

0.46 (0.24)

46

-

0.29 (0.15)

27

-

-


Patients age-group

0.43

0.46

Children < 18 yrs

0.51 (0.18)

18

0.31 (0.10)

18

0.41

Adults

0.44 (0.28)

77

0.28 (0.13)

82

-

Elderly

0.35 (0.13)

5

-

0

-


Mortality outcome

Yes

0.28 (0.17)

11

0.02

0.17 (0.09)

17

<0.001

<0.001

No

0.47 (0.26)

89

-

0.31 (0.12)

83

-

-


Statistician involved

Yes

0.44 (0.27)

46

0.83

0.28 (0.14)

54

0.64

0.69

No

0.45 (0.26)

54

-

0.29 (0.10)

46

-

-


Patients' recruitment

Multicenter

0.38 (0.21)

67

<0.001

0.28 (0.12)

88

0.02

<0.001

Single-center

0.58 (0.30)

33

-

0.36 (0.16)

12

-

-


Funding source

0.18

0.95

0.19

Industry

0.40 (0.22)

50

0.29 (0.12)

70

Institution/private

0.47 (0.32)

33

0.28 (0.14)

25

Not reported/funded

0.53 (0.23)

17

0.29 (0.09)

5


Sample size ≤200

0.67 (0.25) 0.42 (0.10)

37 27

0.38 (0.13) 0.36 (0.09)

10 23

200-400

0.28 (0.07)

14

<0.001

0.28 (0.09)

38

<0.001

**

400-800

0.18 (0.13)

20

0.20 (0.14)

28

>800


*P-value for each factor after adjustment on the type of trial. **There was a significant interaction between superiority/noninferiority type of the trial and sample size.

Gayet-Ageron et al. BMC Medical Research Methodology 2010 10:93   doi:10.1186/1471-2288-10-93

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