Table 5.

Level of evidence and grade of recommendation (n = 17).

Study	Level of Evidence	Design	Level of Recommendation
Afzal et al. 2015 [49]	3B	Individual Case-Control Study	B
Byl et al. 2015 [47]	1B	Individual Randomized Controlled Trial	A
Crea et al. 2015 [48]	3B	Individual Case-Control Study	B
Grewal et al. 2015 [43]	1B	Individual Randomized Controlled Trial	A
Ma et al. 2015 [28]	3B	Individual Case-Control Study	B
Caudron et al. 2014 [67]	3B	Individual Case-Control Study	B
Halicka et al. 2014 [75]	3B	Individual Case-Control Study	B
Franco et al. 2013 [89]	3B	Individual Case-Control Study	B
Nanhoe-Mahabier et al. 2012 [36]	3B	Individual Case-Control Study	B
Nataraj et al. 2012 [63]	3B	Individual Case-Control Study	B
Sungkarat et al. 2011 [50]	1B	Individual Randomized Controlled Trial	A
Alahakone et al. 2010 [110]	3B	Individual Case-Control Study	B
Janssen et al. 2010 [68]	3B	Individual Case-Control Study	B
Giansanti et al. 2009 [64]	3B	Individual Case-Control Study	B
Lee et al. 2007 [51]	3B	Individual Case-Control Study	B
Chiari et al. 2005 [65]	3B	Individual Case-Control Study	B
Wall et al. 2001 [32]	3B	Individual Case-Control Study	B