This coordinated meta-analysis approach has several advantages over traditional literature-based meta-analyses arising from the fact that a collaborative meta-analysis is based on de novo, consistent analyses of harmonized variables in the primary data. First, the consistent analytic approach and harmonized variables greatly ameliorate the effects of two of the chief causes of heterogeneity between individual studies. In particular, meta-analyzing results derived from differing analytic approaches, such as the use of different covariates, different phenotype definitions, and different analytical models, has a clear potential to bias literature-based meta-analyses [40]. Second, the fact that the results are based on de novo analyses allows for the inclusion of previously unpublished data, both from researchers who have not published on the topic before and through updated individual data from research groups who have previously published. Third, coordinated de novo analyses of primary data allow a collaborative meta-analysis to conduct secondary analyses that can aid in the interpretation of the main results. Finally, the coordinated meta-analysis approach allows the examination of more homogeneous subsets of the primary data than is possible through literature review.
