Table II.

Newcastle-Ottawa Scale quality evaluation form.

Study	Representativeness of the exposed cohort	Selection of the nonexposed cohort	Ascertainment of exposure	Outcome of interest not present at start of study	Control for important factor or additional factor	Outcome assessment	Follow-up long enough for outcomes to occur	Adequacy of follow-up of cohorts	Total quality scores
Papavasiliou et al 10	*	*	*	*		*	*		6
Desai et al 11	*	*	*	*		*	*	*	7
Cancienne et al 12	*	*	*	*	**	*	*		8
Khanuja et al 13	*	*	*	*	**	*	*	*	9
Amin et al 14	*	*	*	*		*	*		6
Bedard et al 15	*	*	*	*		*	*	*	7
Richardson et al 16	*	*	*	*		*	*		6
Turcotte et al 17	*	*	*	*		*	*	*	7

A study could be awarded a maximum of one star for each item except for the item “Control for important factor or additional factor”.