Table 3.

Study quality assessment using the Newcastle-Ottawa Scale.

First author, year of publication (reference)	Selection				Comparability	Outcome
	Representativeness of exposed cohort	Selection of nonexposed cohort	Ascertainment of exposure	Outcome of interest absent at start of study		Assessment of outcome	Follow-up long enough for outcomes to occur	Adequacy of follow-up	Total score
Arya [27]	*	*	*	*	* *	*	…	…	7
Avery [19]	*	*	*	*	* *	*	…	…	7
Caillard [8]	*	*	*	*	* *	*	…	…	7
Chaudhry [10]	*	*	*	*	* *	*	…	…	7
Chavarot [17]	*	*	*	*	* *	*	…	*	8
Fisher [23]	*	*	*	*	* *	*	…	…	7
Hardesty [25]	*	*	*	*	* *	*	…	*	8
Linares [26]	*	*	*	*	* *	*	…	*	8
Miarons [9]	*	*	*	*	* *	*	…	…	7
Molnar [11]	*	*	*	*	* *	*	…	…	7
Nair [24]	*	*	*	*	* *	*	…	…	7
Ozturk [20]	*	*	*	*	* *	*	…	*	8
Rinaldi [18]	*	*	*	*	* *	*	…	*	8
Ringer [22]	*	*	*	*	* *	*	…	…	7
Trapani [21]	*	*	*	*	* *	*	*	*	9