Table 1.

Prevalence of Spin by Study Characteristics (N = 59)

	All studies (n = 59) N	Spin present (n = 25) N (%)	Spin absent (n = 34) N (%)	p-value
Funding source				0.89
Industry involvement	36	15 (42)	21 (58)
No industry involvement	23	10 (43)	13 (57)
Financial ties of PI present				0.08
Yes	29	9 (31)	20 (69)
No	30	16 (53)	14 (47)
Any relationship with manufacturer (funding and/or financial ties)
Yes	41	17 (42)	24 (58)	0.83
No	18	8 (44)	10 (56)
Sample size				0.01*
Q1 (24–109)	15	10 (67)	5 (33)
Q2 (110–270)	15	5 (33)	10 (67)
Q3 (271–410)	14	8 (57)	6 (43)
Q4 (411–13,229)	15	2 (13)	13 (87)
First author affiliation by continent				0.17
Europe	22	10 (45)	12 (55)
North America	27	8 (30)	19 (70)
Asia	7	5 (71)	2 (29)
Other	3	2 (67)	1 (33)
First author affiliation by country				0.35
USA	23	8 (35)	15 (65)
Other	36	17 (47)	19 (53)
Specialty				0.63
Cardiology	9	3 (33)	6 (67)
Oncology	7	4 (57)	3 (43)
Other	43	18 (42)	25 (58)
Trial registration				0.69
Yes	53	22 (42)	31(58)
No	6	3 (50)	3 (50)
RCT type				0.93
Phase 2	21	9 (43)	12 (57)
Phase 3	26	10 (38)	16 (62)
Phase 4	4	2 (50)	2 (50)
Other	8	4 (50)	4 (50)
Type of analysis				0.24
Superiority	58	24 (41)	34 (59)
Non-inferiority	1	1 (100)	0 (0)
Comparator				0.59
Placebo	49	20 (41)	29 (59)
Active	10	5 (50)	5 (50)
Outcome measure				0.20
Clinical	45	17 (38)	28 (62)
Surrogate	14	8 (57)	6 (43)
Blinding				0.40
Double-blinded	46	18 (39)	28 (61)
Open-label	12	6 (50)	6 (50)
Single-blinded	1	1 (100)	0 (0)

*Kruskal–Wallis p-value of 0.03 based on medians for studies with spin (201) vs. those without (352)

PI principal investigator