Table 4. NOS scores.

Study	Selection (4 stars)	Comparability (2 stars)	Exposure (3 stars)	Total score (9 stars)
da Silva, 2014a[28]	4 stars	2 stars	3 stars	9 stars
da Silva, 2014b[29]	4 stars	2 stars	2 stars	8 stars
Vetrano, 2014[19]	3 stars	1 star	3 stars	7 stars
Sanchez-Rodriguez, 2014[20]	3 stars	0 star	2 stars	5 stars
Sánchez-Rodríguez, 2015[27]	3 stars	0 star	3 stars	6 stars
Tanimoto, 2013[33]	3 stars	2 stars	3 stars	8 stars
Arango-Lopera, 2013[30]	4 stars	2 stars	2 stars	8 stars
Landi, 2013[21]	4 stars	2 stars	2 stars	8 stars
Landi, 2012a[22]	4 stars	2 stars	2 stars	8 stars
Landi, 2012b[23]	4 stars	2 stars	3 stars	9 stars
Cerri, 2015[24]	3 stars	2 stars	2 stars	7 stars
Woo, 2015[34]	3 stars	2 stars	2 stars	7 stars
Bianchi, 2015[25]	4 stars	2 stars	2 stars	8 stars
Chalhoub, 2015[31]	4 stars	2 stars	1 star	7 stars
Saka, 2015[26]	4 stars	2 stars	3 stars	9 stars
Cawthon, 2015[32]	4 stars	2 stars	1 star	7 stars
Kim, 2014[35]	4 stars	2 stars	2 stars	8 stars