Table 3.

Use of incentives stratified by recruitment continent (n=300)*

Recruitment continent	N	Use of incentives, n (%)
		Yes	No	Not reported
Africa	26	3 (11.5)	1 (3.8)	22 (84.6)
Asia	82	1 (1.2)	2 (2.4)	79 (96.3)
Australia	18	3 (16.7)	0 (0.0)	15 (83.3)
Europe	54	2 (3.7)	3 (5.6)	49 (90.7)
North America	119	33 (27.7)	0 (0.0)	86 (72.3)
South America	9	0 (0.0)	0 (0.0)	9 (100.0)

*Some studies recruited participants from more than one continent.