Application of meta-analysis to specific research fields: Lessons learned

Table 1 Recommendations for performing a valid meta-analysis

Begin with a systematic review of the literature, carefully reviewing original trial publications

Use a standardize data extraction form and independent reviewers to achieve reliable data for the analysis. Use a third reviewer to resolve conflicts

Use current guidelines for standardized reporting of meta-analysis results and incorporate a statistician into the analysis team

If the exposure/intervention/medication has been shown to have different effects within categories, narrow the groups until similar un-confounded groups are formed (for example, by strain of probiotics not by species or by genus, or by type of drug, not by class)

Use caution when using the overall pooled estimate of risk for concluding any type of exposure results in a similar risk of outcome