These can be downloaded, but are not always easy for the researcher to understand or customize. General purpose statistical packages such as SPSS, Stata, SAS, and R can be used to perform meta-analyses, but it is not their primary function and hence they all require external macros or coding.

Some of the studies are not concerned with the assessment of relative risks or odds ratios, but are focused on a summary statistics of incidence or prevalence. Meta-analyses of these studies are becoming more common, particularly after publication of the MOOSE statement. Although reviews of interventional studies, especially clinical trials, provide the best evidence, there are several situations in which observational studies are the only alternative. Performing a search on Pubmed limiting to the type of article, the Mesh term 'meta-analysis' will wield 4223 results in 2010 only. Meta-analyses and systematic reviews are necessary to synthesize the ever-growing data obtained from primary research. More important, to our knowledge this is the first description of a method for producing a statistically adequate but graphically appealing forest plot summarizing descriptive data, using widely available software. It is possible to conduct a meta-analysis using only Microsoft Excel. We have also developed a second spreadsheet capable of producing customized forest plots.

We constructed a step-by-step guide to perform a meta-analysis in a Microsoft Excel spreadsheet, using either fixed-effect or random-effects models. Analyses can be conducted using Microsoft Excel, but there was no previous guide available. Most available softwares have limitations in dealing with descriptive data, and the graphical display of summary statistics such as incidence and prevalence is unsatisfactory. Commercial specialist software is available, but may be expensive and focused in a particular type of primary data. General purpose statistical packages can meta-analyze data, but usually require external macros or coding. Meta-analyses are necessary to synthesize data obtained from primary research, and in many situations reviews of observational studies are the only available alternative.

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