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Table 1 Characteristics of randomized controlled trials with multiple arms by trial design

From: Reporting of analyses from randomized controlled trials with multiple arms: a systematic review

 

All trials, n = 298

Trial design

  

Parallel group, n = 221

Parallel group with factorial, n = 37

Crossovera, n = 40

No. of study groups

    

 3

172 (57.7)

152 (68.8)

0 (0.0)

20 (50.0)

 4

84 (28.2)

39 (17.7)

34 (91.9)

11 (27.5)

 > 4

42 (14.1)

30 (13.6)

3 (8.1)

9 (22.5)

Common specialties

    

 Anesthesia

54 (18.1)

47 (21.3)

3 (8.1)

4 (10.0

 Endocrinology

32 (10.7)

20 (9.1)

5 (13.5)

7 (17.5)

 Cardiology

31 (10.4)

25 (11.3)

6 (16.2)

0 (0.0)

 Infectious disease

22 (7.4)

20 (9.1)

1 (2.7)

1 (2.5)

 Rheumatology

19 (6.4)

18 (8.1)

1 (2.7)

0 (0.0)

Intervention

    

 Drug

192 (64.4)

148 (68.0)

22 (59.5)

22 (55.0)

 Surgery or procedure

17 (5.7)

12 (5.4)

1 (2.7)

4 (10.0)

 Counseling or lifestyle interventions

47 (15.8)

33 (14.9)

10 (27.0)

4 (10.0)

 Equipment or device

26 (8.7)

19 (8.6)

2 (5.4)

5 (12.5)

 Others

16 (6.7)

5 (1.7)

2 (0.7)

9 (3.0)

Study centers

    

 Single

80 (26.9)

54 (24.4)

8 (21.6)

18 (5.0)

 Multiple

141 (47.3)

110 (49.8)

24 (64.9)

7 (13.5)

 Not reported

77 (25.8)

57 (25.8)

5 (13.5)

15 (37.5)

No. of randomized patients per:

    

 Trial, median (10th to 90th percentile)

136 (25 to 800)

148 (45 to 650)

468 (120 to 1653)

21 (12 to 61)

 Arm, median (10th to 90th percentile)

39 (7 to 228)

43 (12 to 204)

117 (30 to 413)

5 (3 to 16)

Cluster trial

13 (4.4)

8 (3.6)

3 (8.1)

2 (5.0)

Trial type

    

 To show superiority

260 (87.3)

195 (88.8)

33 (89.2)

32 (80.0)

 To show non-inferiority or equivalence

12 (4.0)

8 (3.6)

4 (10.8)

0 (0.0)

 Pharmacokinetic/pharmacodynamic objective

26 (8.7)

18 (8.1)

0 (0.0)

8 (20.0)

Randomization design

    

 Balanced

263 (88.3)

190 (86.0)

33 (89.2)

40 (100.0)

 Unbalanced

30 (10.1)

28 (12.7)

2 (5.4)

0 (0.0)

 Unclear

5 (1.7)

3 (1.3)

2 (5.4)

0 (0.0)

Funding source

    

 Solely or partially industry

101 (33.9)

77 (34.8)

11 (29.7)

13 (32.5)

 Public

118 (39.6)

87 (39.4)

14 (37.8)

17 (42.5)

 None

8 (2.7)

6 (2.7)

1 (2.7)

1 (2.5)

 Unknown

71 (23.8)

51 (23.1)

11 (29.8)

9 (22.5.0)

Trial registration reported

144 (48.3)

109 (49.3)

27 (73.0)

8 (20.0)

  1. a There were 4 of the 40 crossover trials with a factorial design.