xmeta-package: A Tool Box for Multivariate Meta-Analysis

In xmeta: A Toolbox for Multivariate Meta-Analysis

A Tool Box for Multivariate Meta-Analysis

Description

The package xmeta consists of a collection of functions for making inference and detecting publication bias in multivariate meta-analysis (MMA).

Inference

The aim of the estimation methods is to estimate the coefficients \boldsymbol{\beta} and the components of the between-study (co)variance matrix \boldsymbol{\Psi} for multivariate random-effects meta-analysis. One major challenge in MMA is the standard inference procedures, such as the maximum likelihood or maximum restricted likelihood inference, require the within-study correlations, which are usually unavailable. Different estimators with and without the knowledge of within study correlation are implemented in the package xmeta. The estimation methods available in function mmeta are:

• Restricted maximum likelihood for MMA with continuous outcomes

• Composite likelihood method for MMA with continuous outcomes

• Method of moment for MMA with continuous outocmes

• Improved method for Riley model for MMA with continuous outcomes

• Marginal bivariate normal model for MMA with binary outcomes

• Marginal beta-binomial model for MMA with binary outcomes

• Hybrid model for disease prevalence along with sensitivity and specificity for diagnostic test accuracy

• Trivariate model for multivariate meta-analysis of diagnostic test accuracy

Small study effects

Detecting and accounting for small study effects are challenging in MMA setting. The multivariate nature is often not fully accounted for by the existing univariate methods. The score test for detecting small study effects in MMA when the within-study correlations are unknown is implemented in the function msset.

Galaxy Plot

A New Visualization Tool of Bivariate Meta-Analysis Studies. This function galaxy returns the galaxy plot to visualize bivariate meta-analysis data, which faithfully retains the information in two separate funnel plots, while providing useful insights into outcome correlations, between-study heterogeneity and joint asymmetry. Galaxy plot is the counterpart of the funnel plot in the multivariate setting. The galaxy plot is an intuitive visualization tool that can aid in interpretation of results of multivariate meta-analysis. It preserves all of the information presented by separate funnel plots for each outcome while elucidating more complex features that may only be revealed by examining the joint distribution of the bivariate outcomes.

Publication bias in bivariate meta-analysis

The function galaxy.trimfill implements a bivariate T&F method accounting for publication bias in bivariate meta-analysis, based on symmetry of the galaxy plot. The bivariate T&F method assumes studies are suppressed based on a weighted sum of the two outcomes. We use a searching algorithm to find the optimal direction which gives the most trimmed studies. This is based on the observation that the closer a direction is to the truth, the more studies are expected to be trimmed along that direction.

xmeta documentation built on Sept. 8, 2023, 5:36 p.m.