Table 2.

Quality score of included studies

Item numbera
ReferenceStudy designb1234567891011131415171819TotalPercentage
Brownson and colleagues, 1991 (28)B0071070000200444404242.4
Zahm and colleagues, 1999 (30)B4671000000040444404747.5
Cerhan and colleagues, 2005 (31)B0671070053200444405656.6
Pan and colleagues, 2005 (32)B0671074053200444406060.6
Keegan and colleagues, 2006 (33)B0671000004240444404949.5
Lim and colleagues, 2007 (29)A81071070403240744407474.7
Lu and colleagues, 2009 (39)A81071070003040744406868.7
Van Veldhoven and colleagues, 2010 (36)A81071074453202744408181.8
Kabat and colleagues, 2011 (37)A81071074053200744407575.8
Parent and colleagues, 2011 (34)B0671000404240444486161.6
Teras and colleagues, 2012 (38)A41071074053200744407171.7
Kelly and colleagues, 2012 (35)B0671070453040444406262.6
  • aThe item numbers refer to the item numbers in the original Quality Score System developed by Monninkhof and colleagues (18).

  • bA, prospective cohort study; B, case–control study.