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

An overview of reviews aims to collect, assess, and synthesize evidence from multiple systematic reviews (SRs) on a specific topic using rigorous and reproducible methods. An important methodological challenge in conducting an overview of reviews is the management of overlapping data due to the inclusion of the same primary studies in SRs. We present a free, open-source R package called ccaR (https://github.com/thdiakon/ccaR) that provides easy-to-use functions for assessing the degree of overlap of primary studies in an overview of reviews with the use of the corrected cover area (CCA) index. A worked example with and without consideration of chronological structural missingness is outlined, illustrating the steps involved in, calculating the CCA index and creating a publication-ready heatmap. We expect ccaR to be useful for overview authors, methodologists, and reviewers who are familiar with the basics of R and contribute to the discussion on different methodological approaches for implementing the CCA index. Future research and applications could further investigate the functionality or potential limitations of our package and other potential uses.

Systematic Review and Meta-Analysis of Cardiovascular Medications in Neonatal Hypotension.

Background: Comparative studies among the various cardiovascular medications used for the treatment of neonatal hypotension are lacking. Methods: This systematic review and pairwise meta-analysis of the anti-hypotensive treatments in preterm and term infants was conducted to evaluate efficacy and impact on outcome. Electronic databases were searched up to February 2021 for relevant articles. As an extension of the current approach for study selection, a machine learning technique was used. Only randomized controlled trials (RCTs) of inotropes, pressors, volume therapy, and corticosteroids were included. Response to treatment was the primary outcome while secondary outcomes included mortality and common morbidities. Results: Nineteen RCTs involving 758 preterm and term neonates were found, and 8 treatments were evaluated. Most studies involved subjects with early hypotension associated with prematurity. Pairwise meta-analysis among treatments showed that dopamine was more effective than dobutamine regarding the response to treatment (restoration of normotension or normalization of blood pressure) (7 trials, 286 neonates, odds ratio, 3.06 [95% CI = 1.06-8.87]; I2 = 49%, very low quality of the evidence per GRADE). Comparisons of other treatments were not significant. No differences were found among regimens regarding survival and other secondary outcomes. Conclusion: In this systematic review and pairwise meta-analysis, only the comparison of dopamine versus dobutamine provided evidence for efficacy of treatment and favored dopamine. No safe conclusions could be reached in regard to other treatments. Data regarding the management of arterial hypotension in conditions other than transition after birth in preterm newborns are sparse both in preterm and term infants.

Methods for depicting overlap in overviews of systematic reviews: An introduction to static tabular and graphical displays.

BACKGROUND AND OBJECTIVE: To introduce potential static tabular and graphical techniques for visually presenting overlap between systematic reviews (SRs) included in overviews of systematic reviews (OoSRs). METHODS: The graphical approaches described include Venn and Euler diagrams, as well as matrix-based, node-link, and aggregation-based techniques. We used fundamental concepts of mathematics from set and network theory to develop our novel graphical approaches. The graphical displays were created using R. RESULTS: Overview authors have the flexibility to choose from a variety of visualizations, depending on the characteristics of their study. If the OoSRs include few SRs, a Venn or an Euler diagram can be used. In case of OoSRs with more SRs, Upset plots, heatmaps, and node-link graphs are more appropriate for visualizing overlapping SRs. Stacked bar plots constitute an aggregation-based technique of illustrating overlap. Strengths and limitations of each graphical approach are presented. CONCLUSION: The degree of overlap should be explored for the entire study and for specific outcomes of interest. The proposed graphical techniques may assist methodologists and authors in identifying overlap, which in turn may improve validity and transparency in OoSRs. More research is needed to understand which technique would be most useful and easiest to understand.