Table 2.
Study classification, identification and results availability in the HPV vaccine industry study programmes and non-industry funded clinical studies
| 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 |
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
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
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)
dSee Additional file 1 for a complete list of the trial registers and databases that we searched
e110 of the 145 industry studies and 39 of the 61 non-industry studies were completed and assessed for publication status
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)
gOther HPV vaccine manufacturers were Shanghai Zerun Biotechnology Co., Ltd. and Xiamen Innovax Biotech Co., Ltd
hP values were calculated for total industry studies vs. total non-industry studies with Fisher’s exact test (http://www.langsrud.com/fisher.htm)