Inter-study differences: how should they influence the interpretation and analysis of results?

Area of Science:

• Biostatistics
• Clinical Epidemiology
• Meta-Analysis Methodology

Background:

• Inter-study variation is a critical consideration in meta-analysis.
• The interpretation of heterogeneity requires careful evaluation of study characteristics.

Purpose of the Study:

• To delineate the role of inter-study variation in meta-analysis.
• To explore how different research questions influence the analysis of variation.
• To provide guidance on selecting appropriate analytical methods based on study objectives.

Main Methods:

• The study discusses three key factors influencing the role of inter-study variation: the research question, study design similarity, and explained outcome heterogeneity.
• It examines three distinct research questions: treatment efficacy in specific circumstances, average treatment effectiveness, and effectiveness in the specific trials analyzed.
• The O-E (Observed-Expected) analysis is highlighted as a method directly addressing effectiveness in the trials at hand.

Main Results:

• The choice of analytical approach should align with the specific question being addressed.
• Under the assumption of no qualitative interaction, different questions yield similar answers.
• The O-E analysis is most suitable for evaluating treatment effectiveness within the specific trials included in the meta-analysis.

Conclusions:

• The interpretation and analysis of inter-study variation must be tailored to the research question.
• Alternative analytical strategies are recommended when the primary interest is in treatment efficacy under specific circumstances.
• The example of aspirin post-myocardial infarction studies illustrates the application of these principles.