Table II.

Quality assessment of studies by Newcastle-Ottawa scale (NOS)

Studies	Selection of cohorts				Comparability of cohorts	Outcome			Total Score
	Representativeness of exposed cohort	Selection of non-exposed cohort	Ascertainment of exposure	Demonstration outcome of interest does not present at start of study	Comparability on the basis design or analysis	Assessment of outcome	Was follow up long enough for outcomes to occur	Adequacy of follow up of cohorts
Gupta et al. [62]	*	*		*	**	*	*		7
Masana et al. [55]	*	*		*	**	*			6
Zhang et al. [52]	*	*	*	*	**	*	*	*	9
Rossi et al. [65]	*	*	*	*	**				6
Cariou et al. [63]	*	*		*	**	*	*	*	8
Saeed et al. [50]	*	*	*	*	**	*	*	*	9
Song et al. [56]	*	*	*	*	**	*	*		8
De Spiegeleer et al. [58]	*	*	*	*	**	*			7
Rodriguez-Nava et al. [53]	*	*		*	**				5
Zenga et al. [66]	*	*		*	**	*	*		7
Nguyen et al. [67]	*	*	*	*	**	*	*		8
Wang et al. [34]	*	*		*	**		*		6
Grasselli et al. [46]	*	*	*	*	**	*	*	*	9
Yan et al. [47]	*	*		*	**	*	*		7
Ayed et al. [68]	*	*	*	*	**	*	*		8
Tan et al. [60]	*	*		*	**	*	*		7
Peymani et al. [64]	*	*	*	*	*	*			7
Nicholson et al. [69]	*	*	*	*	*	*	*	*	9
Lala et al. [70]	*	*	*	*	*	*	*	*	9
Krishnan et al. [35]	*	*		*	**	*	*		7
Argenziano et al. [57]	*	*	*	*	**	*	*	*	9
Daniels et al. [61]	*	*	*	*	**	*	*	*	9
Dreher et al. [59]	*	*	*	*	**	*	*		8
Vahedian-Azimi et al. [54]	*	*	*	*	**	*	*	*	9