Table 3.

Quality measure of included studies by the Newcastle–Ottawa quality assessment scale.

Study	Selection				Comparability		Outcome			TOT
	(1)	(2)	(3)	(4)	(a)	(b)	(1)	(2)	(3)
McGirt et al. [44]	*	*	*		*	*	*	*		7
Derr et al. [32]	*	*	*		*	*	*	*		7
Grommes et al. [25]	*	*	*		*	*	*	*		7
Jones et al. [36]	*	*	*		*	*	*	*		7
Soritau et al. [48]	*	*	*		*	*	*	*		7
Chambless et al. [38]	*	*	*		*	*	*	*		7
Stevens et al. [49]	*	*	*		*	*	*	*		7
Siegel et al. [47]	*	*	*		*	*	*	*		7
Welch & Grommes [51]	*	*	*		*	*	*	*		7
Mayer et al. [43]	*	*	*		*	*	*	*		7
Adeberg et al. [35]	*	*	*		*	*	*	*		7
Tieu et al. [50]	*	*	*		*	*	*	*		7
Seliger et al. [2]	*	*	*		*	*	*	*		7
Barami et al. [37]	*	*	*		*	*	*	*		7
Chen et al. [39]	*	*	*		*	*	*	*		7
Hagan et al. [42]	*	*	*		*	*	*	*		7
Disney-Hogg et al. [41]	*	*	*		*	*	*	*		7
Potharaju et al. [45]	*	*	*		*	*	*	*		7
Decker et al. [40]	*	*	*		*	*	*	*		7
Seliger et al. [46]	*	*	*		*	*	*	*		7

* present.