Table 2. Associations between determinants and publication, expressed as crude and adjusted odds ratios (OR), and 95% confidence intervals (CI) of the crude and adjusted ORs.

Determinants		Crude OR (95% CI)	Adjusted OR (95% CI)
Phase
	Phase 1	ref	ref
	Phase 2	2.9 (1.7–4.8)	2.6 (1.1–5.9)
	Phase 3	5.1 (3.1–8.4)	4.1 (1.7–10.0)
	Phase 4	2.4 (1.3–4.6)	2.4 (0.9–6.3)
	Other than phase 1–4	2.9 (1.7–5.1)	3.2 (1.5–6.5)
Applicant
	Contract research organization	ref	ref
	Investigator or company	1.7 (1.2–2.4)	1.7 (1.1–2.8)
Centers
	Single center	ref	ref
	Multicenter only in the Netherlands	1.4 (0.8–2.5)	1.2 (0.6–2.4)
	Multicenter in the Netherlands and the EU	2.6 (1.5–4.4)	2.2 (1.1–4.4)
	Multicenter in Netherlands and outside EU	3.1 (2.1–4.6)	2.0 (1.0–4.0)
Therapeutic effect expected
	Therapeutic effect expected	ref	ref
	No therapeutic effect expected	0.5 (0.4–0.7)	1.7 (0.9–3.3)
Type of trial
	Intervention	ref	ref
	Invasive observational	1.5 (0.5–4.7)	0.4 (0.2–0.9)
	Non-invasive observational	0.7 (0.2–2.6)	0.9 (0.3–3.2)
Participant category
	≥18 years old and able to provide consent	ref	ref
	<18 years old and/or unable to provide consent	0.8 (0.4–1.5)	0.5 (0.2–1.0)
Disease area
	Oncology	ref	ref
	Other disease areas	0.7 (0.4–1.0)	0.7 (0.4–1.1)
Prospective registration
	Prospectively registered	ref	ref
	Not (prospectively) registered	0.3 (0.2–0.5)	0.5 (0.3–0.8)
Completion
	Completed as planned	Ref	ref
	Terminated early	0.3 (0.2–0.5)	0.2 (0.1–0.3)