Table 3.

Joanna Briggs Institute (JBI) scores for Case–control studies.

Study	Group comparable in the presence of disease in cases and absence of diseases in controls	Cases and controls matched appropriately	Same criteria used for identifying cases and controls	Exposure measured invalid and reliable way	Exposure measured in same way as cases and controls	Confounding factors identified	Strategies to deal with confounding factors stated	Outcomes measured in standard, valid and reliable way for cases and controls	Exposure period of interest long enough to be meaningful	Appropriate statistical analysis used?
Garcez etal. (64) (Brazil)	+	+	+	+	+	+	+	+	–	+
Kazakou etal. (65) (Greece)	+	+	+	+	+	+	+	+	–	+
Özçelik etal. (66) (Turkey)	+	+	+	+	+	−	−	+	–	+