Table 3.

Quality assessment using Newcastle-Ottawa scale of the included studies.

Investigators	Selection	Comparability	Exposure	Total score
Duzagac et al. [17]	☆☆☆☆	☆	☆☆☆	8
Gonçalves et al. [19]	☆☆☆☆	☆☆	☆☆	8
Pradeep et al. [20]	☆☆☆	☆☆	☆☆	7
Pradeep et al. [21]	☆☆☆	☆☆	☆☆	7
Öngöz Dede et al. [22]	☆☆☆		☆☆☆	6
Patel and Raju [23]	☆☆☆☆	☆	☆	6
Fadel et al. [24]	☆☆☆	☆☆	☆	6
Zimmermann et al. [6]	☆☆☆☆	☆☆	☆	7
Pradeep et al. [25]	☆☆☆	☆☆	☆☆	7
Pradeep et al. [26]	☆☆☆	☆☆	☆☆	7
Modéer et al. [16]	☆☆☆	☆	☆☆	6