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Table 1 Characteristics of included articles by registration status (n = 137)

From: Association of trial registration with the results and conclusions of published trials of new oncology drugs

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