Recent Research Trends in Meta-analysis.

The use of meta-analysis (MA), which is placed on top of the evidence hierarchy, in studies has been increasing exponentially. MA has three effect size families. Using the category of effect size families, this paper introduces the important points in the MA process and highlights the recent research trends in this field, such as network MA, meta-analytic structural equation modeling, and diagnostic test accuracy MA. Several reporting standards were established for primary studies and MA. The critical assessment reviews demonstrated that the current quality of nursing MA reporting was low. The problematic areas of the current nursing MA include study search, study selection, risk of bias, publication bias, and additional analysis based on quality assessment. Directions for future research are also presented in this paper.