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Table 2 Study classification, identification and results availability in the HPV vaccine industry study programmes and non-industry funded clinical studies

From: Index of the human papillomavirus (HPV) vaccine industry clinical study programmes and non-industry funded studies: a necessary basis to address reporting bias in a systematic review

Study classification, identification and results availability Industry HPV vaccine studies Non-industry funded HPV vaccine studies P valueh
Total: N = 145 GSK (Cervarix): N = 69 Merck (Gardasil and Gardasil 9): N = 66 Otherg: N = 10 Total: N = 61 Cervarix: N = 6 Gardasil and Gardasil 9: N = 48 Other: N = 7
Study classificationa
 ‘Definitely exists’ 127
(88%)
69
(100%)
50
(76%)
8
(80%)
33
(54%)
5
(83%)
28
(58%)
0
(0%)
< 0.0001
 ‘Probably exists’ 18 (12%) 0 (0%) 16 (24%) 2 (20%) 28 (46%) 1 (17%) 20 (42%) 7 (100%) < 0.0001
Study identification (ID)
 Uses study programme specificb ID 125 (86%) 66 (96%) 49 (74%) 10 (100%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) < 0.0001
 Uses manufacturer specificc ID 98 (68%) 68 (99%) 30 (45%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) < 0.0001
 Uses both study programme and manufacturer specific IDs 95 (66%) 65 (94%) 30 (45%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) < 0.0001
 Uses national clinical study (NCT) ID 132 (91%) 64 (93%) 58 (88%) 10 (100%) 44 (72%) 6 (100%) 33 (69%) 5 (71%) 0.0009
 Uses study programme, manufacturer specific and NCT IDs 91 (63%) 61 (88%) 30 (45%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) < 0.0001
 Uses additional or other ID(s) 42 (29%) 26 (38%) 16 (24%) 0 (0%) 51 (84%) 5 (83%) 40 (83%) 6 (86%) < 0.0001
Study results availability
 Listed in a register or databased 138 (95%) 69 (100%) 59 (89%) 10 (100%) 57 (93%) 6 (100%) 45 (94%) 6 (86%) 0.73
 Listed on ClinicalTrials.gov 132 (90%) 64 (93%) 58 (88%) 10 (100%) 44 (72%) 6 (100%) 33 (69%) 5 (71%) 0.0009
 - Results posted on ClinicalTrials.gov 65 of 132
(44%)
37 of 64
(58%)
28 of 58
(48%)
0 of 10
(0%)
6 of 44
(14%)
0 of 6 (0%) 6 of 33
(18%)
0 of 5
(0%)
0.0002
 - Results posted on ClinicalTrials.gov for completed studies 65 of 110
(58%)
37 of 57
(65%)
28 of 49
(57%)
0 of 4
(0%)
6 of 37
(16%)
0 of 3
(0%)
6 of 29
(21%)
0 of 5
(0%)
< 0.0001
 Published in a biomedical journale 76 of 110
(69%)
42 of 57
(74%)
34 of 49
(69%)
0 of 4
(0%)
16 of 39
(41%)
3 of 3
(100%)
12 of 29
(41%)
1 of 7
(14%)
0.004
 Probably not published in a biomedical journale,f 34 of 110 (31%) 15 of 57 (26%) 15 of 49 (31%) 4 of 4 (100%) 23 of 39 (59%) 0 of 3 (0%) 17 of 29 (59%) 6 of 7 (86%) 0.004
  1. aFor “definitely exists” studies we demanded cross-verification of a studies existence from two or more sources. For ‘probably exists’ studies we demanded verification of a studies existence from one source
  2. bThe HPV vaccine manufacturers usually identified their HPV vaccine study programmes with specific identifiers, for example, “HPV-xxx” for Cervarix and “V50x-xxx” Gardasil and Gardasil 9
  3. cThe HPV vaccine manufacturers usually identified their HPV vaccine studies with manufacturer specific identifiers, for example, GlaxoSmithKline used a six-digit identifier (e.g., 104,896) and Merck Sharp & Dohme used a seven-digit identifier (e.g., 2004_081)
  4. dSee Additional file 1 for a complete list of the trial registers and databases that we searched
  5. e110 of the 145 industry studies and 39 of the 61 non-industry studies were completed and assessed for publication status
  6. f”Probably not published” studies were categorized as such if they were not identified as journal publications in the searches we performed (see Methods and Additional files 1 and 3)
  7. gOther HPV vaccine manufacturers were Shanghai Zerun Biotechnology Co., Ltd. and Xiamen Innovax Biotech Co., Ltd
  8. hP values were calculated for total industry studies vs. total non-industry studies with Fisher’s exact test (http://www.langsrud.com/fisher.htm)