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Table 1 Characteristics of the studies included in the review

From: Correcting for multiple-testing in multi-arm trials: is it necessary and is it done?

  Exploratory trials (n = 20) Confirmatory trials (n = 39) All trials (n = 59)
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%)
  1. Abbreviation: ICD-10, International Classification of diseases, version 10.