3B.) JBI critical appraisal checklist for analytical cross-sectional studies
Study	Criteriaa 1 2 3 4 5 6 7 8	Total/8
Backman et al. (41)	−  +  +  +  +  +  +  +	7/8
Backman et al. (39)	+  +  +  +  +  +  +  +	8/8
Duan et al. (42)	+  +  +  +  +  +  +  +	8/8
Røen et al. (47)	+  +  +  +  +  +  +  +	8/8

^a (1) Inclusion criteria clearly defined. (2) Study subjects and setting described in detail. (3) Exposure measured in a valid and reliable way. (4) Objective, standard criteria used for measurement of the condition. (5) Confounding factors identified. (6) Strategies to deal with confounding factors stated. (7) Outcomes measured in a valid and reliable way. (8) Appropriate statistical analysis used.