Table 2.

Univariable associations (one-way ANOVA) with mean number of difficulties in clinical research

	All difficulties (15 items)		Scientifica difficulties (7 items)		Logisticalb difficulties (7 items)
	Mean	p-value	Mean	p-value	Mean	p-value
Study design		.45		.002		.047
Interventional	2.7		0.9		1.8
Observational	2.9		1.4		1.4
First decision of the REC		.25		.89		.022
Positive, positive with recommendations, positive with written modifications required	2.7		1.1		1.5
Positive with conditions and reassessment, negative/non-consideration	3.1		1.1		2.0
Origin of the study protocol		<.001		<.001		.12
Public (hospital, University, etc.)	3.1		1.4		1.6
Private (industry, foundation)	1.6		0.2		1.3
Sample size		.33		.092		.96
≤ median (100)	2.9		1.3		1.6
> median	2.6		1.0		1.6
Number of centers		<.001		<.001		.21
Single	3.2		1.5		1.7
Multicenter	2.1		0.6		1.5
Type of research		.79		.084		.006
Clinical (intervention, diagnosis, prognosis)	2.8		1.0		1.8
Others (health/illness, public health/health economics, methods, other)	2.7		1.3		1.3
Self-reported trainings in quantitative methods		.37		.16		.80
None	2.9		1.3		1.6
Any	2.7		1.0		1.6
Presence of a statistician on study team (N = 384)		.086		<.001		.54
No	2.9		1.3		1.6
Yes	2.4		0.6		1.7
Study published		.71		.90		.34
No	2.7		1.1		1.5
Yes	2.8		1.1		1.6

^aSum of difficulties reported on the following items: literature review, research question, design, data management, data analysis, manuscript writing, and publication in a peer-reviewed journal

^bSum of difficulties reported on the following items: approval by the Research Ethic Committee, getting funding, approval by the safety agencies, patient enrollment, data collection, collaboration with caregivers for patient enrollment, recruiting competent staff to conduct the study