Table 5.

Consent types stratified by studies from high, upper-middle, lower-middle and low-income countries (n=968)*.

Types of consent	High-income countries		Upper-middle-income countries		Lower-middle-income countries		Low-income countries		Total
	n	%	n	%	n	%	n	%	n	%
Informed consent	76	15.3	109	25.2	20	52.6	0	0.0	205	21.2
Deferred consent	1	0.2	1	0.2	0	0.0	0	0.0	2	0.2
Verbal consent	20	4.0	14	3.2	1	2.6	0	0.0	35	3.6
Waiver of consent	199	40.1	207	47.8	7	18.4	0	0.0	413	42.7
Opt-out	5	1.0	2	0.5	0	0.0	1	100.0	8	0.8
Other types of consent	1	0.2	0	0.0	0	0.0	0	0.0	1	0.1
No consent reported	194	39.1	100	23.1	10	26.3	0	0.0	304	31.4
Total	496	100.0	433	100.0	38	100.0	1	100.0	968	100.0

Data are numbers (n) and percentages (%).

*In four studies, it was unclear in which countries they were conducted; therefore, these four studies were not considered for this analysis.