Table 3

Summary of study quality
Randomised controlled trials Random allocation Baseline measurement Reliability of outcome measure Blinding Adequacy of follow-up Protection against contamination
Donnelly, et al. 2009 [62] Completed Completed Not clear Completed Adequate Completed
Foster, et al. 2008 [55] Completed Completed Sufficient Not blinded Significant loss to follow-up Completed
Controlled before-after studies Second site control Baseline measurement Reliability of outcome measure Blinding Adequacy of follow-up Protection against contamination
Heelan, et al. 2009 [61] Sufficient Completed Sufficient Not clear Significant loss to follow-up Completed
Johnson, et al. 2012 [31] Sufficient Completed Sufficient Not done Adequate Completed
Jordan, et al. 2008 [64] Sufficient Not clear Not clear Not clear Significant loss to follow-up Completed
Cohort Studies Representativeness of the cohort/sample Comparability of cohorts Ascertainment of exposure Assessment of outcome Duration of exposure Adequacy of exposure
Baxter, et al. 2009 [53] Not described Not indicated Measured as part of the study Independent of exposure Sufficient No statement
Chiodera, et al. 2008 [60] Representative Did not control for socioeconomic status or ethnicity Measured as part of the study Independent of exposure Sufficient Sufficient
Chomitz, et al. 2010 [63] Somewhat representative Controlled for ethnicity, socioeconomic status and additional factors Measured as part of the study Independent of exposure Sufficient Subjects lost to follow-up unlikely to introduce bias
Datar and Sturm, 2004 [38] Representative Controlled for ethnicity, socioeconomic status and additional factors Measured as part of the study Independent of exposure Sufficient Subjects lost of follow-up may have introduced bias
Fernandes, 2010 [39] and Fernandes and Sturm, 2011 [40] Representative Controlled for ethnicity, socioeconomic status and additional factors Structured interview Independent of exposure Sufficient Subjects lost to follow-up may have introduced bias
Henry, 2006 [50] Somewhat representative Did not control for socioeconomic status or ethnicity Measured as part of the study Independent of exposure Sufficient Sufficient
Hernandez. Francis and Doyle, 2011 [41] Representative Controlled for ethnicity, socioeconomic status and additional factors Written self report Independent of exposure Sufficient Sufficient
Hinrichs, 2006 [47] Representative Controlled for ethnicity and, socioeconomic status Measured as part of the study Independent of exposure Sufficient No statement
Millimet and Tchernis, 2009 [42] Somewhat representative Controlled for ethnicity, socioeconomic status and additional factors Measured as part of the study Independent of exposure Sufficient Subjects lost to follow-up may have introduced bias
Millimet, Tchernis and Husain, 2008 [43] and 2010 [44] Representative Controlled for ethnicity, socioeconomic status and additional factors Measured as part of the study Independent of exposure Sufficient Sufficient
Ramirez-Lopez, et al. 2005 [54] Somewhat representative Controlled for some factors but not socioeconomic status or ethnicity Measured as part of the study No description Sufficient Subjects lost to follow-up may have introduced bias
Cross-sectional Studies Representativeness of the cohort/sample Comparability of cohorts Ascertainment of exposure Assessment of outcome Duration of exposure Adequacy of exposure
Fox, et al. 2009 [56] Somewhat representative Controlled for ethnicity, socioeconomic status and additional factors Measured as part of the study and structured interviews Independent of exposure Sufficient Sufficient
Jones, et al. 2003 [34] Somewhat representative Controlled for ethnicity and, socioeconomic status Measured as part of the study Independent of exposure Sufficient Sufficient
Harrison, et al. 2011 [57] Somewhat representative Controlled for socioeconomic status Measured as part of the study Independent of exposure Sufficient Subjects lost to follow-up may have introduced bias
Veugelers and Fitzgerald, 2005 [58] Somewhat representative Controlled for socioeconomic status and additional factors Measured as part of the study Independent of exposure Sufficient Sufficient
Zhu, et al. 2010 [59] At risk group Did not control for socioeconomic status or ethnicity Measured as part of the study Independent of exposure Sufficient Subjects lost of follow-up unlikely to introduce bias

Williams et al.

Williams et al. International Journal of Behavioral Nutrition and Physical Activity 2013 10:101   doi:10.1186/1479-5868-10-101

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