This has been a period of transition in meta-analysis, first from its roots in educational and social psychology, where large heterogeneous datasets could be explored to find effect modifiers, to smal

The gap

Consensus across the literature

Supporting evidence — 3 representative gaps

• A systematic review of implant outcomes in treated periodontitis patients (2015) · doi

  The strength of the evidence was limited by the heterogeneity of the included studies in terms of study design, population, therapy, unit of analysis, inconsistent definition of baselines and outcomes, as well as by the inadequate reporting of statistical analysis and accounting for confounding factors; thus, meta-analysis could not be performed.

  Keywords: strength evidence limited heterogeneity included terms design population therapy unit inconsistent definition baselines outcomes well
• Twenty years of network meta‐analysis: Continuing controversies and recent developments (2024) · doi

  This has been a period of transition in meta-analysis, first from its roots in educational and social psychology, where large heterogeneous datasets could be explored to find effect modifiers, to smaller pairwise meta-analyses in clinical medicine on average with less than six studies.

  Keywords: meta period transition first roots educational social psychology large heterogeneous datasets explored find effect modifiers
• A Systematic Review and Meta-Analysis Evaluating the Role of GLP-1 Receptor Agonists in Substance Use Disorders (2026) · doi

  This meta-analysis has some limitations. First, the small number of included RCTs (n = 5 in quantitative synthesis) substantially limits statistical power for subgroup analyses, increases the influence of each study on pooled estimates, and precludes assessment of small-study effects via formal regression tests. Second, marked clinical and methodological heterogeneity limits the clinical interpretability of pooled estimates, particularly for alcohol outcomes. Third, most included trials were short (6-26 weeks), so whether GLP-1RA effects on substance use are maintained with longer treatment or after discontinuation is entirely unknown. Assessment of publication bias was also limited because the number of included studies was too small for reliable funnel plot interpretation or formal asymmetry testing.

  Keywords: small included number limits pooled estimates assessment effects formal clinical meta limitations first rcts quantitative