Table 1 Design characteristics by year started
From: Update on the clinical trial landscape: analysis of ClinicalTrials.gov registration data, 2000–2020
A. Counts of trials started by year | ||||||||||||
Year started | Trials started | Multi-site | Allocation | Intervention model | Masked | Number of treatment groups (Study Arms) | ||||||
N | >1 facility | Randomized | Single group | Parallel | Crossover | Factorial | Sequential | Yes | 1 | 2 | 3+ | |
2000 | 1873 | 926 | 960 | 526 | 738 | 81 | 40 | 5 | 538 | 293 | 377 | 162 |
2001 | 2399 | 1149 | 1403 | 679 | 1076 | 143 | 54 | 3 | 827 | 398 | 534 | 243 |
2002 | 3492 | 1741 | 2246 | 1000 | 1746 | 323 | 64 | 10 | 1257 | 509 | 952 | 320 |
2003 | 4765 | 2272 | 3132 | 1442 | 2478 | 398 | 120 | 9 | 1877 | 770 | 1408 | 491 |
2004 | 6314 | 2941 | 4111 | 1951 | 3351 | 547 | 118 | 10 | 2504 | 1086 | 1863 | 661 |
2005 | 7728 | 3444 | 5065 | 2438 | 4153 | 709 | 165 | 17 | 3219 | 1412 | 2480 | 990 |
2006 | 9297 | 4194 | 6106 | 2951 | 5082 | 855 | 180 | 24 | 3962 | 1893 | 3528 | 1367 |
2007 | 10,412 | 4536 | 6769 | 3328 | 5799 | 926 | 165 | 28 | 4435 | 2446 | 4641 | 1911 |
2008 | 11,874 | 5000 | 7915 | 3669 | 6704 | 1136 | 195 | 31 | 5398 | 2906 | 5847 | 2434 |
2009 | 12,825 | 5139 | 8509 | 3941 | 7291 | 1269 | 180 | 31 | 5644 | 3194 | 6483 | 2544 |
2010 | 13,402 | 5273 | 8970 | 4012 | 7682 | 1359 | 230 | 40 | 5886 | 3309 | 6856 | 2792 |
2011 | 14,175 | 5417 | 9542 | 4119 | 8335 | 1410 | 207 | 43 | 6398 | 3426 | 7503 | 2882 |
2012 | 14,995 | 5629 | 10,000 | 4433 | 8784 | 1433 | 224 | 60 | 6693 | 3684 | 8104 | 3019 |
2013 | 15,829 | 5801 | 10,475 | 4712 | 9278 | 1472 | 241 | 83 | 7025 | 4053 | 8558 | 3137 |
2014 | 17,508 | 6580 | 11,587 | 5010 | 10,351 | 1729 | 251 | 117 | 7754 | 4265 | 9510 | 3663 |
2015 | 18,807 | 7416 | 12,445 | 5225 | 11,426 | 1663 | 260 | 187 | 8214 | 4558 | 10,384 | 3803 |
2016 | 20,168 | 7919 | 13,175 | 5500 | 12,376 | 1724 | 296 | 226 | 8668 | 4987 | 11,070 | 4044 |
2017 | 20,917 | 6511 | 13,663 | 5519 | 12,809 | 1703 | 265 | 619 | 9287 | 5151 | 11,523 | 4136 |
2018 | 22,285 | 6641 | 14,501 | 5826 | 13,540 | 1793 | 279 | 847 | 9848 | 5480 | 12,448 | 4247 |
2019 | 22,847 | 6701 | 14,933 | 6017 | 13,671 | 1894 | 278 | 987 | 10,163 | 5654 | 12,734 | 4346 |
2020 | 22,131 | 7245 | 14,386 | 5868 | 13,427 | 1443 | 270 | 1123 | 9672 | 5510 | 12,314 | 4173 |
Total (/274,043) | 274,043 | 102,475 | 179,893 | 78,166 | 160,097 | 24,010 | 4082 | 4500 | 119,269 | 64,984 | 139,117 | 51,365 |
B. Percent (%) of trials started by year | ||||||||||||
Year started | Facilities | Allocation | Intervention model | Masking | Number of treatment groups (Study Arms) | |||||||
Multi-site | Randomized | Single group | Parallel | Crossover | Factorial | Sequential | Yes | 1 | 2 | 3+ | ||
2000 | 49.4 | 51.3 | 28.1 | 39.4 | 4.3 | 2.1 | 0.3 | 28.7 | 15.6 | 20.1 | 8.6 | |
2001 | 47.9 | 58.5 | 28.3 | 44.9 | 6.0 | 2.3 | 0.1 | 34.5 | 16.6 | 22.3 | 10.1 | |
2002 | 49.9 | 64.3 | 28.6 | 50.0 | 9.2 | 1.8 | 0.3 | 36.0 | 14.6 | 27.3 | 9.2 | |
2003 | 47.7 | 65.7 | 30.3 | 52.0 | 8.4 | 2.5 | 0.2 | 39.4 | 16.2 | 29.5 | 10.3 | |
2004 | 46.6 | 65.1 | 30.9 | 53.1 | 8.7 | 1.9 | 0.2 | 39.7 | 17.2 | 29.5 | 10.5 | |
2005 | 44.6 | 65.5 | 31.5 | 53.7 | 9.2 | 2.1 | 0.2 | 41.7 | 18.3 | 32.1 | 12.8 | |
2006 | 45.1 | 65.7 | 31.7 | 54.7 | 9.2 | 1.9 | 0.3 | 42.6 | 20.4 | 37.9 | 14.7 | |
2007 | 43.6 | 65.0 | 32.0 | 55.7 | 8.9 | 1.6 | 0.3 | 42.6 | 23.5 | 44.6 | 18.4 | |
2008 | 42.1 | 66.7 | 30.9 | 56.5 | 9.6 | 1.6 | 0.3 | 45.5 | 24.5 | 49.2 | 20.5 | |
2009 | 40.1 | 66.3 | 30.7 | 56.8 | 9.9 | 1.4 | 0.2 | 44.0 | 24.9 | 50.5 | 19.8 | |
2010 | 39.3 | 66.9 | 29.9 | 57.3 | 10.1 | 1.7 | 0.3 | 43.9 | 24.7 | 51.2 | 20.8 | |
2011 | 38.2 | 67.3 | 29.1 | 58.8 | 9.9 | 1.5 | 0.3 | 45.1 | 24.2 | 52.9 | 20.3 | |
2012 | 37.5 | 66.7 | 29.6 | 58.6 | 9.6 | 1.5 | 0.4 | 44.6 | 24.6 | 54.0 | 20.1 | |
2013 | 36.6 | 66.2 | 29.8 | 58.6 | 9.3 | 1.5 | 0.5 | 44.4 | 25.6 | 54.1 | 19.8 | |
2014 | 37.6 | 66.2 | 28.6 | 59.1 | 9.9 | 1.4 | 0.7 | 44.3 | 24.4 | 54.3 | 20.9 | |
2015 | 39.4 | 66.2 | 27.8 | 60.8 | 8.8 | 1.4 | 1.0 | 43.7 | 24.2 | 55.2 | 20.2 | |
2016 | 39.3 | 65.3 | 27.3 | 61.4 | 8.5 | 1.5 | 1.1 | 43.0 | 24.7 | 54.9 | 20.1 | |
2017 | 31.1 | 65.3 | 26.4 | 61.2 | 8.1 | 1.3 | 3.0 | 44.4 | 24.6 | 55.1 | 19.8 | |
2018 | 29.8 | 65.1 | 26.1 | 60.8 | 8.0 | 1.3 | 3.8 | 44.2 | 24.6 | 55.9 | 19.1 | |
2019 | 29.3 | 65.4 | 26.3 | 59.8 | 8.3 | 1.2 | 4.3 | 44.5 | 24.7 | 55.7 | 19.0 | |
2020 | 32.7 | 65.0 | 26.5 | 60.7 | 6.5 | 1.2 | 5.1 | 43.7 | 24.9 | 55.6 | 18.9 | |
Average | 40.4 | 64.8 | 29.1 | 55.9 | 8.6 | 1.6 | 1.1 | 41.9 | 22.0 | 44.8 | 16.8 | |