netmeta (version 3.6-0)

metabias.netmeta: Test of funnel plot asymmetry in network meta-analysis

Description

Test of funnel plot asymmetry in network meta-analysis

Usage

# S3 method for netmeta
metabias(
  x,
  order,
  pooled = ifelse(x$random, "random", "common"),
  method.bias = "Egger",
  lump.comparator = gs("lump.comparator"),
  ...
)

Value

A list with class metabias containing the following components if a test for funnel plot asymmetry is conducted:

statistic

Test statistic.

df

The degrees of freedom of the test statistic in the case that it follows a t distribution.

pval

The p-value for the test.

estimate

Estimates used to calculate test statisic.

method

A character string indicating what type of test was used.

title

Title of Cochrane review.

complab

Comparison label.

outclab

Outcome label.

var.model

A character string indicating whether none, multiplicative, or additive residual heterogeneity variance was assumed.

method.bias

As defined above.

x

Network meta-analysis object.

version

Version of R package meta used to create object.

version.netmeta

Version of R package netmeta used to create object.

Or a list with the following elements if test is not conducted due to the number of studies:

k

Number of comparisons.

k.min

Minimum number of comparisons to perform test for funnel plot asymmetry.

version

Version of R package meta used to create object.

version.netmeta

Version of R package netmeta used to create object.

Arguments

x

An object of class netmeta.

order

A mandatory character or numerical vector specifying the order of treatments or list of comparators (see Details).

pooled

A character string indicating whether results for the common ("common") or random effects model ("random") should be used in test of funnel plot asymmetry. Can be abbreviated.

method.bias

A character vector indicating which test(s) for funnel plot asymmatrx to use. Admissible values are "Begg", "Egger", and "Thompson", can be abbreviated. See function metabias.meta.

lump.comparator

A logical indicating whether comparators should be lumped, e.g., to specify inactive treatments. information on direct comparisons should be added to the plot.

...

Additional arguments (passed on to metabias.meta).

Author

Guido Schwarzer

Details

Test of funnel plot asymmetry in network meta-analysis

Argument order is mandatory to determine the order of treatments (Chaimani et al., 2013):

“[...] investigators should order the treatments in a meaningful way and make assumptions about how small studies differ from large ones. For example, if they anticipate that newer treatments are favored in small trials, then they could name the treatments from oldest to newest so that all comparisons refer to ‘old versus new intervention’. Other possibilities include defining the comparisons so that all refer to an active treatment versus placebo or sponsored versus non-sponsored intervention.”

Alternatively, it is possible to only provide a single or few treatment name(s) in argument order to define the comparator(s). In this case only comparisons with this / these treatment(s) will be considered. If argument lump.comparator is TRUE, all comparators will be lumped into a single group.

References

Chaimani A & Salanti G (2012): Using network meta-analysis to evaluate the existence of small-study effects in a network of interventions. Research Synthesis Methods, 3, 161--76

Chaimani A, Higgins JP, Mavridis D, Spyridonos P, Salanti G (2013): Graphical tools for network meta-analysis in STATA. PLOS ONE, 8, e76654

See Also

netmeta, funnel.netmeta, metabias

Examples

# \donttest{
# Transform data from long arm-based to contrast-based format
#
pw <- pairwise(studlab = study, treat = treatment,
  n = n, mean = mean, sd = sd, data = Senn2013,
  varnames = c("MD", "seMD"))

# Conduct network meta-analysis
#
nma <- netmeta(pw)

# Test for asymmetry in 'comparison-adjusted' funnel plot not
# conducted as argument 'order' is missing
#
try(metabias(nma))

# Test for funnel plot asymmetry comparing active treatments with
# placebo
metabias(nma, order = "pl")

# Rank test
#
metabias(nma, order = "pl", method.bias = "Begg")


# Test for funnel plot asymmetry based on (non-sensical) alphabetic
# order of treatments with placebo as last treatment
#
ord <- c("a", "b", "me", "mi", "pi", "r", "si", "su", "v", "pl")
metabias(nma, order = ord)
# }