Table 1

Characteristics of included trials

Trial characteristicsAll trials
(n=405)
Concluded
(n=313)
Potentially ongoing
(n=92)
Number of participants, median (IQR) 80 (32–225)80 (30–230)80 (40–173)
Trial phase, n (%)
  Phase 2186147 (79)39 (21)
  Phase 3 or 2/3132101 (77)31 (23)
  Phase 48765 (75)22 (25)
Funding source, n (%)*
  Industry214187 (87)27 (13)
  NIH/US government2317 (74)6 (26)
  Other233155 (67)78 (33)
Trial start date, n (%)
  Unlisted21 (50)1 (50)
  Prior to 20061514 (93)1 (7)
  2006–20093729 (78)8 (22)
  2010–2011235176 (75)59 (25)
  2012–201411693 (80)23 (20)
Registered retrospectively, n (%)†159124 (78)35 (22)
Registered prospectively, n (%)245189 (77)56 (23)
Major discrepancy in recruitment status‡12591 (73)34 (27)
  • *Trials could have more than one funding source.

  • †Registration timing relative to recruitment could not be determined for one study.

  • ‡Listed recruitment status within ClinicalTrials.gov was incorrect or there was a delay of more than 1 year between when the study concluded and when the registry recruitment status was updated to reflect that recruitment ended.

  • NIH, National Institutes of Health.