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Commit de2b3c1c authored by Christian Roever's avatar Christian Roever
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added 'BucherEtAl1997' data

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......@@ -2,7 +2,7 @@ Package: bayesmeta
Type: Package
Title: Bayesian Random-Effects Meta-Analysis and Meta-Regression
Version: 2.8
Date: 2021-08-23
Date: 2021-08-31
Authors@R: c(person(given="Christian", family="Roever", role=c("aut","cre"),
email="christian.roever@med.uni-goettingen.de",
comment=c(ORCID="0000-0002-6911-698X")),
......
# Data from:
#
# H. C. Bucher et al.
# The results of direct and indirect treatment comparisons
# in meta-analysis of randomized controlled trials
# Journal of Clinical Epidemiology, 50(6):683-691, 1997.
# https://doi.org/10.1016/S0895-4356(97)00049-8
#
# Table 1
#
BucherEtAl1997 <- cbind.data.frame("study" =c("Antinori (1992)", "Mallolas (1992)", "Tocchetti (1994)",
"Bozzette (1995)", "Blum (1995)", "Podzamczer (1993)",
"Podzamczer (1995)", "Sirera (1995)",
"Slavin (1992)", "Girard (1993)", "Torres (1993)",
"Opravil (1995)", "Salmon (1995)",
"Rozenbaum (1991)", "Hardy (1992)", "Schneider (1992)",
"Smith (1992)", "Michelet (1993)", "May (1993)",
"Stellini (1994)", "Nielsen (1995)", "Rizzardi (1995)"),
"treat.A" =factor(rep(c("TMP-SMX", "AP", "TMP-SMX"), c(8,5,9)),
levels=c("TMP-SMX", "D/P", "AP")),
"treat.B" =factor(rep(c("D/P", "D/P", "AP"), c(8,5,9)),
levels=c("TMP-SMX", "D/P", "AP")),
"events.A"=c(1, 3, 0, 42, 1, 3, 0, 6,
8, 10, 15, 13, 12,
0, 14, 0, 3, 1, 2, 0, 1, 5),
"total.A" =c(66, 107, 15, 276, 39, 81, 104, 115,
46, 176, 152, 242, 102,
29, 154, 142, 27, 53, 108, 26, 47, 95),
"events.B"=c(9, 8, 1, 41, 1, 13, 6, 9,
9, 10, 15, 12, 5,
1, 36, 6, 6, 4, 5, 2, 8, 6),
"total.B" =c(63, 116, 15, 288, 47, 85, 96, 105,
50, 173, 126, 291, 92,
27, 156, 71, 26, 55, 106, 23, 48, 101),
stringsAsFactors=FALSE)
\name{BucherEtAl1997}
\docType{data}
\alias{BucherEtAl1997}
\title{Direct and indirect comparison example data}
\description{Numbers of subjects and events in the different treatment arms of 22 studies.}
\usage{data("BucherEtAl1997")}
\format{The data frame contains the following columns:
\tabular{lll}{
\bold{study} \tab \code{character} \tab publication identifier (first author and publication year) \cr
\bold{treat.A} \tab \code{factor} \tab treatment in first study arm (\dQuote{TMP-SMX} or \dQuote{AP}) \cr
\bold{treat.B} \tab \code{factor} \tab treatment in second study arm (\dQuote{D/P} or \dQuote{AP}) \cr
\bold{events.A} \tab \code{numeric} \tab number of events in first study arm \cr
\bold{events.B} \tab \code{numeric} \tab number of events in second study arm \cr
\bold{total.A} \tab \code{numeric} \tab total number of patients in first study arm \cr
\bold{total.B} \tab \code{numeric} \tab total number of patients in second study arm \cr
}
}
\details{Bucher \emph{et al.} (1997) discussed the example case of the
comparison of \emph{sulphametoxazole-trimethoprim (TMP-SMX)} versus
\emph{dapsone/pyrimethamine (D/P)} for the prophylaxis of
\emph{Pneumocystis carinii} pneumonia in HIV patients. Eight
studies had undertaken a head-to-head comparison of both medications,
but an additional 14 studies were available investigating one of the
two medications with \emph{aerosolized pentamidine (AP)} as a
comparator. Nine studies compared TMP-SMX vs. AP, and five studies
compared D/P vs. AP. Together these provide \emph{indirect} evidence
on the effect of TMP-SMX compared to D/P.
The example constitutes a simple case of a \emph{network meta-analysis
(NMA)} setup, where only two-armed studies are considered, and
analysis is based on pairwise comparisons of treatments (or
\emph{contrasts}). In this case, the joint analysis of \emph{direct}
and \emph{indirect} evidence may be implemented as a special case of a
meta-regression (Higgins \emph{et al.}, 2019; Sec. 11.4.2).
The original data in fact included some three-armed studies, in which
case one of the arms was deliberately omitted (Bucher \emph{et al.}; 1997).
}
\source{H.C. Bucher, G.H. Guyatt, L.E. Griffith, S.D. Walter.
The results of direct and indirect treatment comparisons
in meta-analysis of randomized controlled trials.
\emph{Journal of Clinical Epidemiology}, \bold{50}(6):683-691, 1997.
\doi{10.1016/S0895-4356(97)00049-8}.
}
\references{J.P.T. Higgins, J. Thomas, J. Chandler, M. Cumpston, T. Li,
M.J. Page, V.A. Welch (eds.).
\emph{Cochrane handbook for systematic reviews of interventions}.
Wiley and Sons, 2nd edition, 2019.
\doi{10.1002/9781119536604}.
\url{http://handbook.cochrane.org/}.
}
\examples{
# load data:
data("BucherEtAl1997")
# show data:
head(BucherEtAl1997)
\dontrun{
# compute effect sizes (log-ORs for pairwise comparisons)
# from the count data:
es <- escalc(measure="OR",
ai=events.A, n1i=total.A, # "exposure group"
ci=events.B, n2i=total.B, # "control group"
slab=study, data=BucherEtAl1997)
# specify regressor matrix:
X <- cbind("TMP.DP" = rep(c(1, 0, 1), c(8,5,9)),
"AP.DP" = rep(c(0, 1,-1), c(8,5,9)))
# perform Bayesian meta-regression:
bmr01 <- bmr(es, X=X)
# show default output:
print(bmr01)
# specify contrast matrix:
contrastX <- rbind("TMP-SMX vs. D/P"=c(1,0),
"AP vs. D/P" =c(0,1),
"TMP-SMX vs. AP" =c(1,-1))
# show summary including contrast estimates:
summary(bmr01, X.mean=contrastX)
# show forest plot including contrast estimates:
forestplot(bmr01, X.mean=contrastX, xlab="log-OR")
# perform frequentist meta-regression:
fmr01 <- rma(es, mods=X, intercept=FALSE)
print(fmr01)
# compare Bayesian and frequentist results;
# estimated log-OR for "TMP-SMX" vs. "D/P"
rbind("bayesmeta"=bmr01$summary[c("mean","sd"),"TMP.DP"],
"rma" =c(fmr01$beta["TMP.DP",], fmr01$se[1]))
# estimated log-OR for "AP" vs. "D/P"
rbind("bayesmeta"=bmr01$summary[c("mean","sd"),"AP.DP"],
"rma" =c(fmr01$beta["AP.DP",], fmr01$se[2]))
# estimated heterogeneity:
rbind("bayesmeta"=bmr01$summary["median","tau"],
"rma" =sqrt(fmr01$tau2))
}
}
\keyword{datasets}
......@@ -17,7 +17,7 @@
Package: \tab bayesmeta\cr
Type: \tab Package\cr
Version: \tab 2.8\cr
Date: \tab 2021-08-23\cr
Date: \tab 2021-08-31\cr
License: \tab GPL (>=2)
}
The main functionality is provided by the \code{\link{bayesmeta}()}
......
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