Table 6

Study sample size, overall and broken down by outcome type, intervention comparison type and medical area

Studies

25%

50%

75%

Max


All

Total

112600

44

91

210

1242071


Data type

Dichotomous

77237

50

102

243

1242071

Continuous

29902

33

62

142

18851

Mixed

5461

21

86

251

36511


Medical specialty

Cancer

6441

72

154

326

266064

Cardiovascular

10686

44

102

289

67800

Central nervous system/musculoskeletal

8299

43

80

149

9440

Digestive/endocr., nutritional and metabolic

15345

42

79

160

18819

Gynaecology, pregnancy and birth

20098

60

118

293

23697

Infectious diseases

4502

59

130

371

419748

Mental health and behavioural conditions

15218

36

63

165

9020

Pathological conditions, symptoms and signs

4448

40

61

115

2463

Respiratory diseases

13153

36

87

227

82892

Urogenital

5914

39

71

153

4912

Other

8496

44

90

198

1242071


Interventions

Pharm. vs. Control/Placebo

44156

41

90

222

58050

Pharm. vs. Pharm.

28018

48

99

222

25180

Pharm. vs. Non-Pharm.

2018

50

74

135

7711

Non-Pharm. vs. Control/Placebo

20892

41

92

229

1242071

Non-Pharm. vs. Non-Pharm.

17516

45

85

169

82892


Outcomes

Signs/symptoms reflecting continuation/end of condition

17621

42

83

197

359600

Adverse events

11898

49

100

242

82892

Infection/onset of new acute/chronic disease

11284

56

110

258

1242071

Biological markers

10578

35

64

147

266064

General physical health

8959

30

66

177

131271

Obstetric outcomes

7376

60

117

293

18453

All-cause mortality

8302

52

110

281

259627

Resource use/hospital stay/process

5454

50

98

200

419748

Cause-specific mortality/major morbidity event/composite (mortality or morbidity)

5413

69

165

449

266064

Other outcomes (semi-objective)1

10886

44

81

177

131271

Other outcomes (subjective)2

14490

38

71

162

359600


1Other outcomes (semi-objective): External structure, Internal structure, Surgical/device related success/failure, Withdrawals/drop-outs

2Other outcomes (subjective): Pain, Mental health outcomes, Quality of life/functioning, Consumption, Satisfaction with care, Composite (at least 1 non-mortality/morbidity)

Davey et al. BMC Medical Research Methodology 2011 11:160   doi:10.1186/1471-2288-11-160

Open Data