Table 3.

Types of methodological approaches

Category		n	References
1	Direct comparison	6	[53, 104, 119, 121, 124, 127]
2	Indirect comparison	7	[122, 123, 126, 128, 138, 139, 149]
3	Interaction/moderation	7	[125, 130, 131, 137, 146–148]
4	Modeling/stratification	3	[140, 151, 152]
5	Combination	12	[40, 82, 120, 129, 132–134, 136, 143–145, 153]