Table 1

Characteristics of included articles by registration status (n = 137)

Characteristic

Prior registration

N = 54

No Prior Registration

N = 83


Publication characteristics


Peer reviewed

53 (98%)

76 (92%)


Year of publication

1996-2002

0 (0%)

29 (35%)

2003-2004

12 (22%)

28 (34%)

2005-2006

14 (26%)

19 (23%)

2007-2008

28 (52%)

7 (8%)


Impact factor, median (interquartile range)*

15.5 (10.9-34.8)

5.8 (4.0-10.5)


First or main report

45 (83%)

70 (84%)


Study design characteristics


Comparison group


Placebo

40 (74%)

32 (39%)


Active treatment only

14 (26%)

51 (62%)


Non-inferiority trial - Yes

2 (4%)

9 (11%)


Primary efficacy outcome = survival

21 (39%)

9 (11%)


Stringent blinding (2/3 points)

16 (30%)

20 (24%)


Sample size, median (interquartile range)

696 (150-923)

283 (99-565)


Statistical significance of primary outcome


Favorable to test drug

36 (67%)

44 (53%)


Inconclusive

18 (33%)

37 (45%)


Unfavorable

0 (%)

2 (2%)


Conclusion


Favorable to test drug

43 (80%)

55 (66%)


About equal

10 (18%)

22 (27%)


Unfavorable

1 (2%)

6 (7%)


Sponsored by test drug maker

47 (87%)

62 (75%)


*Only 127 articles were published in journals with a corresponding impact factor.

Rasmussen et al. Trials 2009 10:116   doi:10.1186/1745-6215-10-116

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