Table 3.

Reasons for excluding retrieved articles on longitudinal studies

Study	Reasons for exclusion
Althoff CE, et al. (2009) [71]	Insufficient result presentation
Aydin SZ, et al (2011) [72]	< 20 controls
Baraliakos X, et al. (2008) [73]	No controls
Battafarano DF, et al. (1993) [74]	< 20 controls
Bennett AN, et al. (2008) [7]	No controls
Bigot J, et al. (1999) [75]	< 20 control
Brandt J, et al. (1999) [76]	No controls
Chiowchanwisawakit P, et al. (2011) [77]	No controls
Dougados M, et al. (2001) [78]	Insufficient result presentation
Hermann J, et al. (2009) [79]	Insufficient result presentation
Madsen K, et al. (2010) [80]	No controls
Macsymowych WP, et al. (2010) [81]	No controls
Marzo-Ortega H, et al. (2008) [82]	< 20 in each control group
Oostveen J, et al. (1999) [83]	No controls
Pedersen SJ, et al. (2011) [84]	No controls
Puhakka KB, et al. (2004) [85]	No controls
Remplik P, et al. (2005) [86]	< 20 cases
Shankar S, et al. (2009) [87]	Insufficient result presentation
Song IH, et al. (2011) [88]	No controls

Studies may have met exclusion criteria other than those listed in the table.