Table 3 Presence and Pre-specification of Adjusted Analyses in Published RCTs a
From: Ideal vs. real: a systematic review on handling covariates in randomized controlled trials
Adjusted Analyses Present (N = 298) | Pre-Specified Adjustment (N = 249) b | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
No | Yes | p-value | No | Yes | p-value | |||||
N | % | N | % | N | % | N | % | |||
Type of Study | 0.6856 | 0.3791 | ||||||||
Superiority | 40 | 16 | 215 | 84 | 19 | 9 | 196 | 91 | ||
Non-Inferiority | 5 | 22 | 18 | 78 | 1 | 6 | 17 | 94 | ||
Other | 4 | 20 | 16 | 80 | 3 | 19 | 13 | 81 | ||
Number of Arms | 0.4884 | 0.3666 | ||||||||
2 | 37 | 16 | 199 | 84 | 19 | 10 | 180 | 90 | ||
3 | 5 | 21 | 19 | 79 | 3 | 16 | 16 | 84 | ||
4 | 4 | 15 | 22 | 85 | 1 | 5 | 21 | 95 | ||
5 or more | 3 | 25 | 9 | 75 | 0 | 0 | 9 | 100 | ||
Multicenter Study | 0.0865 | 0.0458 | ||||||||
No | 7 | 29 | 17 | 71 | 4 | 24 | 13 | 76 | ||
Yes | 42 | 15 | 232 | 85 | 19 | 8 | 213 | 92 | ||
Number of Centers, median (IQR) | 8 (3,32) | 25 (7,77) | 0.1562 | 10 (2,63) | 28 (8,77) | 0.3187 | ||||
Number of Subjects, median (IQR) | 449 (124,1030) | 580 (250,1489) | 0.6507 | 700 (179,1408) | 568 (267,1502) | 0.6488 | ||||
Length of Study, Years, median (IQR) | 3 (2,4) | 3 (2,5) | 0.0996 | 3 (2,6) | 3 (2,5) | 0.6060 | ||||
Months of Subject Follow-up, median (IQR) | 6 (3,14) | 12 (5,24) | 0.1011 | 12 (3,24) | 12 (6,23) | 0.6069 | ||||
Study Initiation Year | 0.7281 | 0.0029 | ||||||||
Unable to Determine | 3 | 60 | 2 | 40 | 0 | 0 | 2 | 100 | ||
Before 2000 | 1 | 6 | 16 | 94 | 5 | 31 | 11 | 69 | ||
2000–2004 | 12 | 16 | 63 | 84 | 7 | 11 | 56 | 89 | ||
2005–2009 | 22 | 18 | 101 | 82 | 9 | 9 | 92 | 91 | ||
2010 and later | 11 | 14 | 67 | 86 | 2 | 3 | 65 | 97 | ||
Primary Outcome | 0.0526 | 0.2586 | ||||||||
Continuous | 12 | 13 | 77 | 87 | 6 | 8 | 71 | 92 | ||
Binary | 27 | 24 | 86 | 76 | 11 | 13 | 75 | 87 | ||
Time-to-Event | 8 | 10 | 76 | 90 | 4 | 5 | 72 | 95 | ||
Other | 2 | 17 | 10 | 83 | 2 | 20 | 8 | 80 | ||
Covariates Involved in Allocation | 0.0100 | 0.1980 | ||||||||
No | 16 | 28 | 41 | 72 | 6 | 15 | 35 | 85 | ||
Yes | 33 | 14 | 208 | 86 | 17 | 8 | 191 | 92 | ||
Number of Covariates | 0.0312 | 0.2949 | ||||||||
N/A | 16 | 28 | 41 | 72 | 6 | 15 | 35 | 85 | ||
1 | 19 | 20 | 76 | 80 | 6 | 8 | 70 | 92 | ||
2 | 8 | 9 | 78 | 91 | 5 | 6 | 73 | 94 | ||
3 | 6 | 15 | 34 | 85 | 2 | 6 | 32 | 94 | ||
4 | 0 | 0 | 11 | 100 | 3 | 27 | 8 | 73 | ||
5 or more | 0 | 0 | 9 | 100 | 1 | 11 | 8 | 89 | ||
Baseline Test for Significant Differences | 0.3033 | 0.7216 | ||||||||
Unable to Determine | 2 | 40 | 3 | 60 | 0 | 0 | 3 | 100 | ||
No | 30 | 18 | 137 | 82 | 12 | 9 | 125 | 91 | ||
Yes | 17 | 13 | 109 | 87 | 11 | 10 | 98 | 90 | ||