\title{studies on the effectiveness of intravenous magnesium in acute myocardial infarction}
\description{results from 16 trials examining the effectiveness of intravenous magnesium in the prevention of death following acute myocardial infarction.}
\bold{id}    \tab \code{numeric}   \tab trial id number \cr
\bold{study} \tab \code{character} \tab first author or trial name \cr
\bold{year}  \tab \code{numeric}   \tab publication year \cr
\bold{ai}    \tab \code{numeric}   \tab number of deaths in the magnesium group \cr
\bold{n1i}   \tab \code{numeric}   \tab number of patients in the magnesium group \cr
\bold{ci}    \tab \code{numeric}   \tab number of deaths in the control group \cr
\bold{n2i}   \tab \code{numeric}   \tab number of patients in the control group
the dataset includes the results from 16 randomized clinical trials that examined the effectiveness of intravenous magnesium in the prevention of death following acute myocardial infarction. studies 1-7 were included in the meta-analyses by teo et al. (1991) and horner (1992) and were combined with the results from the limit-2 trial (woods et al., 1992) in yusuf et al. (1993), suggesting that magnesium is an effective treatment for reducing mortality. however, the results from the isis-4 mega trial (isis-4 collaborative group, 1995) indicated no reduction in mortality with magnesium treatment. publication bias has been suggested as one possible explanation for the conflicting findings (egger & davey smith, 1995).
the present dataset includes some additional trials and are based on table 18.2 from egger, davey smith, and altman (2001).
egger, m., davey smith, g., & altman, d. g. (eds.) (2001). \emph{systematic reviews in health care: meta-analysis in context} (2nd ed.). london: bmj books.
egger, m., & davey smith, g. (1995). misleading meta-analysis: lessons from \dquote{an effective, safe, simple} intervention that wasn't. \emph{british medical journal}, \bold{310}(6982), 752--754. \verb{https://doi.org/10.1136/bmj.310.6982.752}
horner, s. m. (1992). efficacy of intravenous magnesium in acute myocardial infarction in reducing arrhythmias and mortality: meta-analysis of magnesium in acute myocardial infarction. \emph{circulation}, \bold{86}(3), 774--779. \verb{https://doi.org/10.1161/01.cir.86.3.774}
isis-4 collaborative group (1995). isis-4: a randomised factorial trial assessing early oral captopril, oral mononitrate, and intravenous magnesium sulphate in 58,050 patients with suspected acute myocardial infarction. \emph{lancet}, \bold{345}(8951), 669--685. \verb{https://doi.org/10.1016/s0140-6736(95)90865-x}
teo, k. k., yusuf, s., collins, r., held, p. h., & peto, r. (1991). effects of intravenous magnesium in suspected acute myocardial infarction: overview of randomised trials. \emph{british medical journal}, \bold{303}(6816), 1499--1503. \verb{https://doi.org/10.1136/bmj.303.6816.1499}
woods, k. l., fletcher, s., roffe, c., & haider, y. (1992). intravenous magnesium sulphate in suspected acute myocardial infarction: results of the second leicester intravenous magnesium intervention trial (limit-2). \emph{lancet}, \bold{339}(8809), 1553--1558. \verb{https://doi.org/10.1016/0140-6736(92)91828-v}
yusuf, s., teo, k., & woods, k. (1993). intravenous magnesium in acute myocardial infarction: an effective, safe, simple, and inexpensive treatment. \emph{circulation}, \bold{87}(6), 2043--2046. \verb{https://doi.org/10.1161/01.cir.87.6.2043}
### meta-analysis of trials 1-7 using peto's method (as in teo et al., 1991)
res <- rma.peto(ai=ai, n1i=n1i, ci=ci, n2i=n2i, data=dat, subset=1:7)
### meta-analysis of trials 1-7 and limit-2 (as in yusuf et al., 1993)
res <- rma.peto(ai=ai, n1i=n1i, ci=ci, n2i=n2i, data=dat, subset=c(1:7,14))
### meta-analysis of all trials except isis-4
res <- rma.peto(ai=ai, n1i=n1i, ci=ci, n2i=n2i, data=dat, subset=-16)
### meta-analysis of all trials including isis-4
res <- rma.peto(ai=ai, n1i=n1i, ci=ci, n2i=n2i, data=dat)
### contour-enhanced funnel plot centered at 0
funnel(res, refline=0, level=c(90, 95, 99), shade=c("white", "gray", "darkgray"))
medicine, cardiology, peto's method, publication bias