Table 4.
Breakdown of United States Authorship Versus International Authorship for All Studies (Preclinical, n = 257; Clinical, n = 985)
| Authorship | Preclinical | Clinical | |||||
| 1999-2019 | 1994 | 1999 | 2004 | 2009 | 2014 | 2019 | |
| Ave. authors (n ± SD) | 4.63 ± 1.8 | 3.12 ± 1.3 | 3.61 ± 2.0 | 3.52 ± 1.6 | 3.82 ± 1.9 | 4.81 ± 1.9 | 5.62 ± 2.1 |
| Only United States authors (n) | 175 | 87 | 66 | 90 | 88 | 96 | 95 |
| Any non-United States authors (n) | 82 | 26 | 48 | 75 | 114 | 109 | 91 |
| Multiple countriesa (n) | 26 | 1 | 5 | 5 | 10 | 31 | 22 |
| % Only United States authors | 68.1 | 77.0 | 57.9 | 54.5 | 43.6 | 46.8 | 51.1 |
a
Indicates articles that listed authors from ≥ 2 countries, including United States.
Percentage of only US authors calculated by the number of articles with only US authorship divided by the number of articles with at least one non-US author.