Table 2.

Primary studies included in meta-analyses

First author (Year)	Schroeder D (1997)	Majewski M (2000)	Lim J (2001)	Gigante A (2008)	Aktas S (2009)	Valencia AJA (2009)
Khan RJ (2005)	+		+
Khan RJ (2010)	+		+	+	+
McMahon SE (2011)	+	+	+	+	+	+
Jones MP (2012)	+		+	+	+