Funnel plots. Six funnel plots were drawn: three for response and three for remission, for each head to head direct meta-analysis. The P-value given for each funnel is the result of the rank correlation test of funnel plot asymmetry. NA, test not applicable (<10 studies in the meta-analysis).
Naudet et al. BMC Medicine 2013 11:230 doi:10.1186/1741-7015-11-230