ccaR: A package for assessing primary study overlap across systematic reviews in overviews

Area of Science:

• Medical Informatics
• Biostatistics
• Evidence Synthesis

Background:

• Overviews of reviews synthesize evidence from multiple systematic reviews (SRs).
• Managing overlapping primary studies included in SRs is a key methodological challenge.
• Existing methods for quantifying study overlap can be complex.

Purpose of the Study:

• To introduce ccaR, a novel, free, open-source R package.
• To provide accessible functions for calculating the corrected cover area (CCA) index.
• To facilitate the assessment of primary study overlap in overviews of reviews.

Main Methods:

• Development of the ccaR R package.
• Implementation of functions for calculating the CCA index.
• Demonstration using a worked example, including handling chronological missingness.
• Generation of publication-ready heatmaps for visualizing study overlap.

Main Results:

• The ccaR package offers user-friendly tools for CCA index calculation.
• The worked example illustrates practical application and heatmap generation.
• The package effectively addresses the challenge of managing overlapping data in evidence synthesis.

Conclusions:

• ccaR simplifies the assessment of primary study overlap in overviews of reviews.
• The package is a valuable resource for researchers and methodologists involved in evidence synthesis.
• Future work can explore further applications and limitations of the ccaR package.