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Table 2 Characteristics of primary reports of randomised trials (n = 258)

From: Influence of peer review on the reporting of primary outcome(s) and statistical analyses of randomised trials

Characteristic

n = 258

Journal type

 General medical

118 (46%)

 Specialty

140 (54%)

Most common specialties

 Oncology

44 (17%)

 Cardiology

42 (16%)

 Paediatrics

26 (10%)

 Anaesthesia

22 (8%)

 Public health

18 (7%)

Most common countries where trial was conducted

 USA

40 (22%)

 UK

27 (15%)

 Netherlands

16 (9%)

 Australia

4 (2%)

 Not reported

38 (20%)

Trial designa

 Parallel

225 (86.5%)

 Cluster

16 (6%)

 Factorial

11 (4%)

 Crossover

8 (3%)

 Split-body

1 (0.5%)

Intervention

 Drug

127 (49%)

 Surgery/procedure

59 (23%)

 Behavioural/education

40 (16%)

 Biological/vaccine

12 (5%)

 Device

9 (3%)

 Dietary supplement

6 (2%)

 Other

5 (2%)

Study centres

 Single

46 (18%)

 Multiple

191 (74%)

 Unclear

21 (8%)

Number of intervention groups

 2

202 (78%)

 3

35 (13.5%)

 4

20 (8%)

 > 4

1 (0.5)

Median sample size (IQR)b

325 (138 to 1010)

 10 to 90 percentile

(60 to 2485)

Primary outcome clearly defined

 Defined

238 (92%)

 Not defined

20 (8%)

Statistical significance of primary outcome (where defined)c

 Significant

116 (49%)

 Non-significant

122 (51%)

Trial registration

 Reported

235 (91%)

 Not reported

23 (9%)

Trial protocol accessible

 Reported

141 (55%)

 Not reported

117 (45%)

Source of funding

 Solely industry

52 (20%)

 Part industry

27 (10%)

 Non-industry

159 (62%)

 No funding

7 (3%)

 Not reported

13 (5%)

  1. aMore than one trial design is applicable (n = 3), bExcluding cluster randomised trials (n = 242), cPrimary outcome clearly defined (n = 238). IQR interquartile range