Table 1 Descriptive characteristics of included studies (n = 122)
| Â | Frequency (%) |
|---|---|
Year of publication | Â |
 <= 1989 | 1 (0.8) |
 1990 to 1999 | 11 (9.0) |
 2000 to 2009 | 32 (26.2) |
 2010 to 2020 | 78 (63.9) |
Country | Â |
 USA | 53 (43.4) |
 UK | 40 (32.8) |
 Australia | 11 (9.0) |
 Canada | 6 (4.9) |
 Other | 12 (9.8) |
Trial participation decision | Â |
 Real | 78 (63.9) |
 Hypothetical | 44 (36.1) |
Clinical specialty of host trial | Â |
 Oncology | 36 (29.5) |
 Cardiology | 9 (7.4) |
 Injury prevention | 8 (6.6) |
 Endocrinology | 6 (4.9) |
 Psychiatry | 5 (4.1) |
 Smoking cessation | 5 (4.1) |
 Gynecology | 5 (4.1) |
 Infectious disease | 4 (3.3) |
 Orthopedics | 4 (3.3) |
 Pulmonology | 4 (3.3) |
 Neurology | 3 (2.5) |
 Multiple specialties | 9 (7.4) |
 Other | 24 (19.7) |
Host trial phase | Â |
 Phase II | 4 (3.3) |
 Phase III | 50 (41.0) |
 Phase IV | 3 (2.5) |
 Multiple trials/phases | 23 (18.9) |
 Other | 42 (34.4) |