Table 2.

Risk of bias of the included studies

Author, publication year	Study design	Selection				Comparability	Outcome		Score	Interpretation
		Representativeness of the sample	Sample size	Nonrespondents	Ascertainment of exposure	Based on design and analysis	Assessment of outcome	Statistical test
Costarelli et al., 2012 [14]	Cross-sectional		+		+  +	+	+		5	High risk of bias
Muros et al., 2016 [15]	Cross-sectional	+	+		+  +	+  +	+		7	Low risk of bias
Zervaki et al., 2017 [16]	Cross-sectional				+  +	+	+		4	High risk of bias
Evaristo et al., 2018 [17]	Cross-sectional	+	+	+	+  +	+  +	+	+	9	Low risk of bias
Esteban-Gonzalo et al., 2019* [18]	Cross-sectional				+  +	+	+	+	5	High risk of bias
Ferrer-Cascales et al., 2019 [19]	Cross-sectional	+	+	+	+  +	+  +	+		8	Low risk of bias
Delgado-Floody et al., 2020 [20]	Cross-sectional	+			+  +	+	+	+	6	High risk of bias
Rodriguez-Rosado et al., 2020 [21]	Cross-sectional				+  +	+	+		4	High risk of bias
Caamaño-Navarrete et al., 2021 [22]	Cross-sectional		+	+	+  +	+	+	+	7	Low risk of bias
Mitri et al., 2021 [23]	Cross-sectional	+	+		+  +	+	+		6	High risk of bias
Mozzillo et al., 2021 [24]	Cross-sectional	+			+  +	+	+	+	6	High risk of bias

^*Originally a longitudinal study, it was considered the baseline cross-sectional cohort