Table 3. Sample Sizes for the 135 144 Completed Trials by Lead Sponsor and Phase Over Time.
| Start year, lead sponsor | Sample size, median (IQR) | |||
|---|---|---|---|---|
| Phase 1-2a | Phase 3-4b | Phase NAc | All trials | |
| 2000-2004 | ||||
| NIH/US government | 48 (29-85) | 223 (80-727) | 150 (50-400) | 60 (32-157) |
| Industry | 51 (30-120) | 300 (122-600) | 109 (36-341) | 140 (48-400) |
| Other | 42 (24-78) | 120 (50-338) | 99 (40-243) | 68 (32-195) |
| Total | 47 (27-92) | 210 (80-500) | 100 (40-277) | 86 (38-266) |
| 2005-2009 | ||||
| NIH/US government | 44 (24-83) | 150 (49-400) | 98 (30-257) | 55 (26-139) |
| Industry | 48 (26-108) | 258 (106-538) | 72 (35-173) | 91 (36-273) |
| Other | 38 (20-67) | 85 (40-206) | 70 (32-172) | 60 (29-140) |
| Total | 42 (24-87) | 150 (60-400) | 70 (32-178) | 66 (30-190) |
| 2010-2014 | ||||
| NIH/US government | 36 (20-69) | 149 (64-480) | 70 (33-206) | 48 (25-124) |
| Industry | 42 (24-90) | 251 (101-513) | 60 (30-140) | 66 (30-204) |
| Other | 33 (18-64) | 74 (40-162) | 62 (30-153) | 59 (28-130) |
| Total | 39 (20-77) | 120 (50-325) | 62 (30-152) | 60 (29-150) |
| 2015-2019 | ||||
| NIH/US government | 37 (20-72) | 111 (61-357) | 53 (28-123) | 47 (25-100) |
| Industry | 39 (22-74) | 247 (105-515) | 46 (23-100) | 53 (25-140) |
| Other | 30 (15-60) | 70 (36-134) | 52 (27-109) | 50 (25-104) |
| Total | 36 (19-70) | 110 (50-291) | 51 (26-108) | 51 (25-114) |
| 2000-2019d | ||||
| NIH/US government | 42 (24-80) | 180 (64-506) | 89 (34-253) | 55 (28-140) |
| Industry | 45 (24-95) | 261 (108-540) | 57 (28-131) | 75 (32-236) |
| Other | 36 (20-66) | 80 (40-198) | 60 (30-145) | 58 (28-128) |
| Total | 40 (22-80) | 140 (56-379) | 60 (30-146) | 60 (30-160) |
Abbreviations: IQR, interquartile range; NA, not applicable; NIH, National Institutes of Health.
a
Includes early phase 1, phase 1, phase 1 to 2, and phase 2 trials.
b
Includes phase 2 to 3, phase 3, phase 3 to 4, and phase 4 trials.
c
Phase NA is defined as trials without a US Food and Drug Administration–defined phase, including trials of devices or behavioral interventions.
d
Totals exclude missing data. Enrollment data are missing for 1514 records.