Table 2

Reporting of randomized controlled trials with multiple arms by trial design
All trials, n = 298 Trial design
Parallel group, n = 221 Parallel group with factorial, n = 37 Crossover (n = 40)
Reporting item
Study hypothesis defined 238 (79.9) 173 (78.3) 33 (89.1) 32 (80.0)
Baseline characteristics available per group 253 (84.9) 196 (88.7) 28 (75.7) 29 (72.5)
Results on outcomes available per group 250 (83.9) 190 (85.0) 27 (73.0) 33 (82.5)
Global test comparison
 Planned 171 (57.4) 127 (57.5) 23 (62.2) 21 (52.5)
 Reported 116 (38.9) 84 (38.0) 18 (48.7) 14 (35.0)
Pairwise test comparisons
 Planned 180 (60.4) 144 (65.2) 11 (29.7) 25 (62.5)
 Reported 204 (68.5) 162 (73.3) 15 (40.5) 27 (67.5)
Sample-size calculation
 Reported 210 (70.5) 159 (72.0) 30 (81.1) 21 (52.5)
 Taken into account in the multi-arm design 41/210 (19.5) 35/159 (22.0) 5/30 (16.7) 1/21 (4.8)
Adjustment method used to control type I error due to multiple-arm designa 118 (39.6) 89 (40.3) 10 (27.0) 19 (47.50)
Title identified the study as a multiple-arm trial 130 (43.6) 101 (45.7) 19 (51.4) 10 (25.0)

a For sample-size calculation or for statistical analysis.

Baron et al.

Baron et al. BMC Medicine 2013 11:84   doi:10.1186/1741-7015-11-84

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