Table 1 Characteristics of the studies included in the review

Number of study arms

 3

8 (40%)

22 (56%)

30 (51%)

 4

3 (15%)

13 (33%)

16 (27%)

 > 4

9 (45%)

4 (10%)

13 (22%)

Trial design

 Parallel group

19 (95%)

30 (77%)

49 (83%)

  a) Different doses or regimens of same treatment

13

16

29

  b) Different treatments

3

8

11

  c) Combined treatments

3

6

9

 Parallel group with factorial

1 (5%)

9 (23%)

10 (17%)

Comparisons reported (restricted to parallel group trials)

  All pairwise

2/19 (11%)

4/30 (13%)

6/49 (12%)

  Multiple experimental versus control

11/19 (58%)

19/30 (63%)

30/49 (61%)

  Experimental versus multiple controls

1/19 (5%)

2/30 (7%)

3/49 (6%)

  Other

5/19 (26%)

5/30 (17%)

10/49 (20%)

ICD-10 Disease classification

 Certain infectious and parasitic diseases

3 (15%)

5 (13%)

8 (14%)

 Neoplasms

0 (0%)

5 (13%)

5 (8%)

 Endocrine, nutritional and metabolic diseases

4 (20%)

4 (10%)

8 (14%)

 Diseases of the nervous system

1 (5%)

4 (10%)

5 (8%)

 Diseases of the circulatory system

5 (25%)

4 (10%)

9 (15%)

 Other

7 (35%)

17 (44%)

24 (41%)

Allocation ratio

 Equal

18 (90%)

31 (79%)

49 (83%)

 Not Equal

2 (10%)

8 (21%)

10 (17%)

Adjustment procedure

 None

9 (45%)

21 (54%)

30 (51%)

 Bonferroni

2 (10%)

6 (15%)

8 (14%)

 Dunnett

0 (0%)

3 (8%)

3 (5%)

 Hochberg

1 (5%)

3 (8%)

4 (7%)

 Hierarchical (or other closed procedure)

8 (40%)

6 (15%)

14 (24%)

Sample size calculation reported

 In report

16 (80%)

30 (77%)

46 (78%)

 Referenced or in supplementary material

2 (10%)

6 (15%)

8 (14%)

 Not given

2 (10%)

3 (8%)

5 (8%)