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Table 2 Characteristics of completed phase 3 or 4 randomized clinical trials with a superiority hypothesis according to whether significant results (i.e., p-value <0.05 or treatment effect with 95% CI not including the null value) were reported at ClinicalTrials.gov

From: Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials

Characteristics

Categories

Trials with significant results reported

(N = 844)

Trials with non statistically significant results or no treatment effect estimate or p-value reported

(N = 1979)

p-value

Phase of the study

Phase 3

622 (74)

1054 (53)

<0.0001

Phase 4

222 (26)

925 (47)

Intervention type

Drug

675 (80)

1427 (72)

<0.0001

Mixed interventions

97 (11)

231 (12)

Biological

29 (3)

115 (6)

Device

22 (3)

115 (6)

Other

21 (2)

91 (5)

Control group

Placebo or no treatment

543 (64)

795 (40)

<0.0001

Active treatment

301 (36)

1184 (60)

Sponsorship

Industry totally or partly

744 (88)

1473 (74)

<0.0001

Academic only

100 (12)

506 (26)

Countries

Single country

361 (43)

1267 (64)

<0.0001

Multiple countries

353 (42)

507 (26)

Not reported

130 (15)

205 (10)

Location

At least one site in the USA

493 (59)

1175 (59)

0.003

No site in the USA

221 (26)

599 (30)

Not reported

130 (15)

205 (10)

Subject to the FDAAA

Yes

588 (70)

1206 (61)

<0.0001

No

201 (24)

732 (37)

Not reported

55 (6)

41 (2)

Centers

Multicenter

581 (69)

1044 (53)

<0.0001

Single center

133 (16)

730 (37)

Not reported

130 (15)

205 (10)

Sample size

Median (Q1-Q3)

305 (139–541)

179 (62–405)

<0.0001

Time to results first received at ClinicalTrials.gov (month)

Median (Q1-Q3)

13.0 (11.6–26.3)

16.5 (12.0–30.9)

<0.0001

  1. Data are presented as n (%) unless indicated. FDAAA US Food and Drug Administration Amendments Act, Q1-Q3: Quartile 1-Quartile 3