Table 2 Characteristics of unpublished trials with and without results available in the ClinicalTrials.gov results database. Values are numbers (percentages) unless stated otherwise
| Trial characteristics | Results in ClinicalTrials.gov | |
|---|---|---|
| Available (n=38) | Not available (n=133) | |
| Mean (SD) No of participants | 1199 (1049) | 1911 (10 244) |
| Trial phase*: | ||
| I/II | 5 (13) | 36 (27) |
| III | 24 (63) | 80 (60) |
| IV | 8 (21) | 10 (8) |
| Other | 1 (3) | 7 (5) |
| Funding source†: | ||
| Industry | 38 (100) | 112 (84) |
| NIH/US government | 0 (0) | 11 (8) |
| Other | 0 (0) | 20 (15) |
| Trial completion date: | ||
| Unlisted | 0 (0) | 18 (11) |
| Prior to 2005 | 0 (0) | 3 (2) |
| 2005-06 | 3 (8) | 19 (14) |
| 2007 | 5 (13) | 50 (38) |
| 2008 | 30 (79) | 43 (32) |
NIH=National Institutes of Health.
*Trials described as “phase II/III” in their registry entry are categorized as phase III.
†Trials with multiple funding sources are listed within all relevant categories; totals therefore add to more than 100%.