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Table 2 Distribution of 108 included articles by study characteristics (study design, continent of first author’s affiliation, and presence or absence of a declared financial competing interest) and registration status (prospective, retrospective and unregistered)

From: When are clinical trials registered? An analysis of prospective versus retrospective registration

  Prospectively registered studies (n = 33) Retrospectively registered studies (n = 72) Unregistered studies (n = 3)
Study design  
 - RCT 26 56 1
 - Pilot RCT 4 7 1
 - Interventional, non-randomised 3 9 1
Continent of affiliation (first author)  
 - Africa 1 1 0
 - Asia 6 17 1
 - Australia 3 8 0
 - Europe 17 33 1
 - North America 5 8 1
 - South America 1 5 0
Financial competing interests (CI) of any authors  
 - Financial CI declared 8 8 0
 - No financial CI declared 25 64 3