Table 2.

Methodological assessment according to the Newcastle–Ottawa scale

Study	Selection				Comparability	Outcome			Total scorea
	Representativeness	Selection	Ascertainment	Outcome of interest		Assessment	FU	Adequacy of FU
Abe et al. [29]	*	*	*	*	**	–	*	–	7
Arbuthnot et al. [30]	*	*	*	*	*	–	*	*	7
Atkinson et al. [42]	*	*	*	*	*	–	*	*	7
Berger et al. [43]	*	*	*	*	–	*	–	*	6
Bohm [44]	*	*	*	*	**	–	*	*	8
Chatterji et al. [31]	*	*	*	*	**	–	*	–	7
Clyde et al. [45]	–	*	*	*	**	–	*	–	6
Danielsson [46]	*	*	*	*	*	–	*	*	7
Del Piccolo et al. [40]	*	*	*	*	*	*	*	–	7
Dubs et al. [28]	–	*	*	*	–	–	*	*	5
Hara et al. [32]	*	*	*	*	**	–	*	–	7
Huch et al. [33]	*	*	*	*	**	–	*	*	8
Innmann et al. [34]	*	*	*	*	*	–	*	*	7
Johnsson and Persson [47]	*	*	*	*	**	*	*	*	9
Karampinas et al. [35]	–	*	*	*	*	–	*	–	5
Kleim et al. [12]	*	*	*	*	**	–	–	–	6
Kirschak et al. [48]	*	*	*	*	**	*	*	*	9
Lefevre et al. [36]	–	*	–	*	*	–	*	–	4
Leichtenberg et al. [13]	*	*	*	*	**	–	*	*	8
Mikkelsen et al. [49]	–	*	*	*	*	–	–	*	5
Mobasheri et al. [50]	*	*	*	*	**	–	*	*	8
Mont et al. [39]	–	*	–	*	*	–	*	–	4
Nevitt et al. [62]	*	*	*	*	**	–	*	*	8
Pagnano et al. [51]	–	*	*	*	*	–	–	*	5
Peak et al. [52]	*	*	*	*	–	*	–	–	5
Poehling-Monaghan et al. [53]	*	–	*	–	–	–	–	–	2
Pons [54]	*	*	*	*	–	*	*	–	6
Pop et al. [61]	–	*	*	*	*	–	*	–	5
Raguet et al. [41]	–	*	*	*	*	–	*	*	6
Sankar et al. [55]	*	*	*	*	**	–	*	*	8
Schmidutz et al. [37]	*	*	*	*	**	–	*	*	8
Suarez et al. [56]	*	*	*	*	**	*	–	–	7
Suckel et al. [38]	–	*	–	*	–	–	*	–	3
Tilbury et al. [57]	*	*	*	*	**	–	*	*	8
Truszczynska et al. [58]	*	*	*	*	*	*	*	–	7
Visuri et al. [59]	*	*	*	*	**	*	*	*	9
White [60]	–	*	*	*	*	*	*	*	7

FU follow-up

– indicates no stars

^aWe considered a study to be of high quality when the total score was eight or nine stars, moderate quality when the total score was six or seven stars, and low quality when the total score was five stars or fewer