Methods for meta-analysis and meta-regression of proportions: concepts and tutorial with Stata command metapreg

Abstract Background: Despite the widespread use of meta-analysis of proportions, its rationale, certain theoretical and methodological concepts are poorly understood.The framework of logistic regression is well-established and provides a natural and optimal model for meta-analysis, network meta-analysis, and meta-regressionof proportions. Nonetheless, classical tools for meta-analysis of proportions based on approximation to the normal distribution continue to dominate. Methods: We explain the rationale and concepts essential in understanding statistical methods for meta-analysis of proportions. We then present metapreg; a flexible model-based tool with advanced statistical procedures to perform ameta-analysis, network meta-analysis, and meta-regression of proportions in Stata. The tool implements the logistic and the logistic-normal regression, andmarginal standardization to yield population-averaged estimates. Finally, we demonstrate using metapreg with data from four published meta-analyses; a)cure rate of treatment for cervical pre-cancer using cold coagulation, b)incomplete excision of cervical precancer as a predictor of treatment failure, c)effect of geographical area on the protective effect of BCG vaccination againsttuberculosis and d) response rate to treatment of acute mania in adults withdiverse drugs. Conclusion: metapreg is an efficient and user-friendly statistical tool dedicatedt o meta-analysis, network meta-analysis and meta-regression of binomial data. It allows both continuous and categorical explanatory covariates including relevant interactions to explain the variability in the proportions.