Table 3 Factors independently associated with reporting statistically significant results (i.e., reporting a p-value <0.05 or treatment effect with 95% CI not including the null value) for the first primary outcome posted at ClinicalTrials.gov for completed superiority clinical trials

Phase of the trial

Phase 3 versus 4

1.68 (1.38–2.04)

<0.0001

Intervention

Drug versus other

1.20 (0.97–1.48)

0.10

Control group

Inactive versus active

2.19 (1.83–2.61)

<0.0001

Sponsorship

Industry (totally or partially) versus academic

1.57 (1.22–2.03)

0.0005

FDAAA

Subject versus not subject

1.15 (0.94–1.41)

0.17

Countries

Multiple countries versus single country

1.58 (1.29–1.93)

<0.0001

Not reported versus single country

1.50 (1.14–1.98)

0.004

Sample size

For an increase of 100 patients

1.002 (0.99–1.005)

0.20