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Table 2 Authorship, writing, funding and manufacturer involvement characteristics by group

From: Characterisation of trials where marketing purposes have been influential in study design: a descriptive study

  All trials YES trials MAYBE trials NO trials p value (YES vs. MAYBE vs. NO) p value (YES+ MAYBE vs. NO) p value (MAYBE + NO vs. YES)
n = 194 n = 41 n = 14 n = 139
Byline author from the product manufacturer? 76 (39) 35 (85) 10 (71) 31 (22) <.001 <.001 <.001
Median (LQ, UQ) proportion of byline authors from product manufacturer 0 (0, 16) 22 (9, 38) 19 (0, 28) 0 (0, 0) <.001a <.001b <.001b
Byline author reporting a financial conflict of interest with the product manufacturer?c 126 (65) 39 (95) 14 (100) 73 (53) <.001 <.001 <.001
Median (LQ, UQ) proportion of byline authors reporting COI with product manufacturerc 24 (0, 67) 82 (59, 100) 64 (49, 85) 6 (0, 40) <.001a <.001b <.001b
Group name on the byline 111 (57) 25 (61) 9 (64) 77 (55) .701 .415 .584
Is writing or editorial assistance in preparing the manuscript acknowledged?      .001 <.001 .002
Acknowledgements or main text 75 (39) 25 (61) 9 (64) 41 (30)    
Professional writer is a byline author 2 (1) 1 (2) 0 (0) 1 (1)    
No assistance is acknowledged 117 (60) 15 (37) 5 (36) 97 (70)    
Study explicitly funded by product manufacturer? 106 (55) 41 (100) 14 (100) 51 (37) <.001 <.001 <.001
Manufacturer involved in the design of the study?      <.001 <.001 <.001
Yes 71 (37) 34 (83) 10 (71) 27 (19)    
No 96 (50) 4 (10) 2 (14) 90 (65)    
Not explicitly described 27 (14) 3 (7) 2 (14) 22 (16)    
Manufacturer involved in the data analysis?      <.001 <.001 <.001
Yes 66 (34) 35 (85) 10 (71) 21 (15)    
No 106 (55) 4 (10) 3 (21) 99 (71)    
Not explicitly described 22 (11) 2 (5) 1 (7) 19 (14)    
Manufacturer involved in the reporting of the study?      <.001 <.001 <.001
Yes 64 (33) 33 (81) 10 (71) 21 (15)    
No 98 (51) 3 (7) 1 (7) 94 (68)    
Not explicitly described 32 (17) 5 (12) 3 (21) 24 (17)    
Manufacturer control over the design of the study?      <.001 <.001 <.001
Yes 24 (12) 14 (34) 3 (21) 7 (5)    
No 108 (56) 9 (22) 3 (21) 96 (69)    
Not explicitly described 62 (32) 18 (44) 8 (57) 36 (26)    
Manufacturer had control over the data analysis?      <.001 <.001 <.001
Yes 39 (20) 23 (56) 5 (36) 11 (8)    
No 111 (57) 7 (17) 4 (29) 100 (72)    
Not explicitly described 44 (23) 11 (27) 5 (36) 28 (20)    
Manufacturer control over reporting of the study?      <.001 <.001 <.001
Yes 20 (10) 9 (22) 2 (14) 9 (7)    
No 111 (57) 11 (27) 4 (29) 96 (69)    
Not explicitly described 63 (33) 21 (51) 8 (57) 34 (25)    
  1. Figures in brackets are percents unless specified otherwise.a Kruskal Wallis Test.b Mann Whitney U Test.c n = 3 data not available as links to the COI forms do not work
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