Drawing Contour-Enhanced Funnel Plot in R Software

Objective To introduce how to draw a contour-enhanced funnel in R software and its application in meta-analysis. Methods It was illustrated on an example data to draw a contour-enhanced funnel by using funnel（） function and trimfill（） function in meta package in R software, and to perceive the missing studies in areas of statistical significance from the plot. Results The contour-enhanced funnel was asymmetry, and the studies seem to be missing in areas of non-significance, and it was explained that funnel plot asymmetry may be due to publication bias. Conclusions Contour-enhanced funnel could be used to help distinguish publication bias from other cause of funnel plot asymmetry.