The nlme package is developed based on the generalized least squares (gls) and linear mixed-effects model (lme). It can perform meta-analysis based on linear and nonlinear mixed effects models in R language. When conducting meta-analysis using nlme package in R language, the first step is to translate the data into its logarithm estimation. In this article, we introduce how to perform network meta-analysis using R language nlme package and show the core step of data translation in detail.
R software is a free and powerful statistical software, which has the functions of data processing and graphics drawing and is widely used in the meta-analysis. This article introduced detailed operation steps of rmeta package which is suitable for meta-analysis of binary data, and also can finish cumulative meta-analysis, draw standard summary plots, forest plot and funnel plot. In summary, the functions of rmeta package are simple and easy to mastery. There are some limitations of current version which need to be improved in the future.
Does-response meta-analysis, which has being developed for more than 30 years, is a type of regression function and can be both linear and non-linear model. It plays an important role in investigating the relationship between dependent and independent variable. With its special advantages, dose-response meta-analysis has been widely used in evidence-based practice and decision. Currently there are several models can be used to perform dose-response metaanalysis with various advantages and disadvantages. It is vital to choose best model to perform dose-response metaanalysis in evidence-based practice. In this paper, we briefly introduce and summarize the methodology of dose-response meta-analysis.
Restricted cubic spline function is an ideal model in trend approximation, which is widely used in doseresponse meta-analysis. The spline function, based on parameter technique, is a smoothly joined piecewise polynomial of each knot, with a cubic polynomial in each sub-interval of the slope which fits well in the non-linear trend by changing the number and (or) the sites of the knots. We have introduced the methodology of linear and non-linear slope model in dose-response meta-analysis in the previous article, and in this one, we will give a more detailed discussion on restricted cubic spline function mainly in the following aspects: model building, parameters pooling and knots selecting.
Structural equation modeling (SEM) is a frequently used multivariate technique in social, psychology, educational, behavioral science. Meta-analytic structural equation modeling (MASEM) combines the ideas of metaanalysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. A two-stage structural equation modeling (TSSEM) approach to conducting MASEM that was based on a fixed-effects model will be introduced. To introduce the operation of metaSEM package for multivariate meta-analyst, we are adopt the fixed-effects model, assumes that the population correlation matrices based on TSSEM, to analyze the instance data.
As a valid method in systematic review, dose-response meta-analysis is widely used in investigating the relationship between independent variable and dependent variable, and which usually based on observational studies. With large sample size, observational studies can provide a reasonable amount of statistical power for meta-analysis. However, due to the design defects of observational studies, they tend to introduce many kinds of biases, which may influence the final results that make them deviation from the truth. Given the dead zone of methodology, there is no any bias adjusting method in dose-response meta-analysis. In this article, we will introduce some bias adjusting methods from other observational-study-based meta-analysis and make them suit for dose-response meta-analysis, and then compare the advantages and disadvantages of these methods.
ObjectiveTo develop reporting guideline for dose-response meta-analysis (DMA), so as to help Chinese authors to understand DMA better and to promote the reporting quality of DMA conducted by them. MethodPubMed, EMbase, The Cochrane Library, CNKI, and WanFang Data were searched from Jan 1st 2011 to Dec 30th 2015 to collect DMA papers published by Chinese authors. The number of these publications by years, whether and what kind of reporting guideline was used, and whether the DMA method claimed in these publications was correct were analysed. Then we drafted a checklist of items for reporting DMA, and organized a discussion meeting with experts from the fields of DMA, evidence-based medicine, clinical epidemiology, and clinicians to collect suggestions for revising the draft reporting guideline for DMA. ResultsOnly 33.73% of the publications clarified it is a DMA on the title and 48.02% of them reported risk of bias. Almost 38.49% of the publications didn't use any reporting guidelines. Fourteen of them claimed an incorrect use of methodology. We primarily took account for 47 potential items related to DMA based on our literature analysis results and existing reporting guidelines for other types of meta-analyses. After the discussion meeting with 6 experts, we revised the items, and finally the G-Dose checklist with 43 items for reporting DMA was developed. ConclusionThere is a lack of attention on reporting guidelines in Chinese authors and evidence suggests these authors may be at risk of incomplete understanding on reporting guidelines. It is strongly recommended to use reporting guidelines for DMA and other types of meta-analyses in Chinese authors.