Table 1. Characteristics of included studies.

Author Name	Year	Region	Groups	Total
Awan et al. [10]	2020	Pakistan	Reduced	589
			Preserved	625
Dalen et al. [11]	2016	Sweden	Reduced	3456
			Preserved	1216
Dalen et al. [11]	2017	Sweden	Reduced	10,069
			Preserved	27,165
Hamad et al. [5]	2010	Netherlands	Reduced	2081
			Preserved	8204
Sun et al. [12]	2018	Canada	Reduced	4816
			Preserved	2752
Sun et al. [12]	2019	Canada	Reduced	10,284
			Preserved	22,231
Thuijs et al. [13]	2020	United States	Reduced	115
			Preserved	796