Table 1.

Characteristics of the published and unpublished studies included in the analysis (n = 62)

	Published		Unpublished		p(chi-square)	Total
	N	%	N	%		N	%
Studies funded and started	39	62.9	23	37.1		62	100.0
Clinical area					0.604
Oncology/hematology	11	28.2	8	34.8		19	30.6
Congenital and genetic disorders	13	33.3	4	17.4		17	27.4
Immune system disorders	4	10.3	3	13.0		7	11.3
Other	11	28.2	8	34.8		19	30.6
Prevalence of rare disease					0.381
> 1/10,000	14	35.9	7	30.4		21	33.9
1–9/100,000	12	30.8	11	47.8		23	37.1
1–9/1,000,000	13	33.3	5	21.8		18	29.0
Study characteristics
Design					0.055
Randomized clinical trials (RCT)	21	53.8	18	78.3		39	62.9
Uncontrolled clinical trials (CT)	18	46.2	5	21.7		23	37.1
Type of control group (n = 39)	21	100.0	18	100.0	0.584	39	100.0
Active control	11	52.4	11	61.1		22	56.4
Placebo control/no treatment	10	47.6	7	38.9		17	43.6
Planned sample size (tertiles)					0.901
< =46 patients	13	33.3	8	34.8		21	33.9
47-100 patients	14	35.9	7	30.4		21	33.9
> 100 patients	12	30.8	8	34.8		20	32.3
Mean	98		107			101
Median	60		80			60
Q1-Q3	30–120		29–177			30–124
Special populations					0.307
Only pediatrics	12	30.8	6	26.1		18	29.0
Also pediatrics	4	10.3	0	0.0		4	6.5
Only adults	15	38.5	9	39.1		24	38.7
Adults and elderly	8	20.5	8	34.8		16	25.8