M. Er -4 years ago 232
R Question

# How to combine forest plots in package metafor?

Assume the code below (as given in http://www.metafor-project.org/doku.php/plots:forest_plot_with_subgroups)

``````library(metafor)

### decrease margins so the full space is used
par(mar=c(4,4,1,2))

### fit random-effects model (use slab argument to define study labels)
res <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg, measure="RR",
slab=paste(author, year, sep=", "), method="REML")

### set up forest plot (with 2x2 table counts added; rows argument is used
### to specify exactly in which rows the outcomes will be plotted)
forest(res, xlim=c(-16, 6), at=log(c(.05, .25, 1, 4)), atransf=exp,
ilab=cbind(dat.bcg\$tpos, dat.bcg\$tneg, dat.bcg\$cpos, dat.bcg\$cneg),
ilab.xpos=c(-9.5,-8,-6,-4.5), cex=.75, ylim=c(-1, 27),
order=order(dat.bcg\$alloc), rows=c(3:4,9:15,20:23),
xlab="Relative Risk", mlab="RE Model for All Studies", psize=1)

### set font expansion factor (as in forest() above) and use bold italic
### font and save original settings in object 'op'
op <- par(cex=.75, font=4)

### add text for the subgroups
text(-16, c(24,16,5), pos=4, c("Systematic Allocation",
"Random Allocation",
"Alternate Allocation"))

### switch to bold font
par(font=2)

text(c(-9.5,-8,-6,-4.5), 26, c("TB+", "TB-", "TB+", "TB-"))
text(c(-8.75,-5.25),     27, c("Vaccinated", "Control"))
text(-16,                26, "Author(s) and Year",     pos=4)
text(6,                  26, "Relative Risk [95% CI]", pos=2)

### set par back to the original settings
par(op)

### fit random-effects model in the three subgroups
res.s <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg, measure="RR",
subset=(alloc=="systematic"), method="REML")
res.r <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg, measure="RR",
subset=(alloc=="random"), method="REML")
res.a <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg, measure="RR",
subset=(alloc=="alternate"), method="REML")

### add summary polygons for the three subgroups
addpoly(res.s, row=18.5, cex=.75, atransf=exp, mlab="RE Model for Subgroup")
addpoly(res.r, row= 7.5, cex=.75, atransf=exp, mlab="RE Model for Subgroup")
addpoly(res.a, row= 1.5, cex=.75, atransf=exp, mlab="RE Model for Subgroup")
``````

This code gives the following combined forest plot:

So my question is how to remove the total relative risk and its corresponding results at the very bottom of the plot? In other words, I just want to plot some forest plots and show them at the same plot, but do not want to combine them and show the outcome results.

In the `forest(...)` part, use `addfit=FALSE`. And then you also want to adjust the `ylim` value. In this case, `ylim=c(1, 27)` should work.

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