Screening nonrandomized studies for medical systematic reviews: a comparative study of classifiers
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Objectives To investigate whether (1) machine learning classifiers can help identify nonrandomized studies eligible for full-text screening by systematic reviewers; (2) classifier performance varies with optimization; and (3) the number of citations to screen can be reduced.Methods We used an open-source, data-mining suite to process and classify biomedical citations that point to mostly nonrandomized studies from 2 systematic reviews. We built training and test sets for citation portions and compared classifier performance by considering the value of indexing, various feature sets, and optimization. We conducted our experiments in 2 phases. The design of phase I with no optimization was: 4 classifiers × 3 feature sets × 3 citation portions. Classifiers included k-nearest neighbor, naïve Bayes, complement naïve Bayes, and evolutionary support vector machine. Feature sets included bag of words, and 2- and 3-term n-grams. Citation portions included titles, titles and abstracts, and full citations with metadata. Phase II with optimization involved a subset of the classifiers, as well as features extracted from full citations, and full citations with overweighted titles. We optimized features and classifier parameters by manually setting information gain thresholds outside of a process for iterative grid optimization with 10-fold cross-validations. We independently tested models on data reserved for that purpose and statistically compared classifier performance on 2 types of feature sets. We estimated the number of citations needed to screen by reviewers during a second pass through a reduced set of citations.Results In phase I, the evolutionary support vector machine returned the best recall for bag of words extracted from full citations; the best classifier with respect to overall performance was k-nearest neighbor. No classifier attained good enough recall for this task without optimization. In phase II, we boosted performance with optimization for evolutionary support vector machine and complement naïve Bayes classifiers. Generalization performance was better for the latter in the independent tests. For evolutionary support vector machine and complement naïve Bayes classifiers, the initial retrieval set was reduced by 46% and 35%, respectively.Conclusions Machine learning classifiers can help identify nonrandomized studies eligible for full-text screening by systematic reviewers. Optimization can markedly improve performance of classifiers. However, generalizability varies with the classifier. The number of citations to screen during a second independent pass through the citations can be substantially reduced.
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Employing machine learning tools as the second screener in a reviewer pair could overcome concerns about reliability.
“Bekhuis et al. [24–26] found that employing machine learning tools as the second screener in a reviewer pair could overcome concerns about reliability.”
From Technology-assisted title and abstract screening for systematic reviews: a retrospective evaluation of the Abstrackr machine learning tool (2018) · cites this paper as [24]
The Introduction describes a machine-learning system that reduces the citations for a second, independent screening pass and says this could help control reviewer bias and error. But that second screening is performed by different human teammates; the paper does not propose the tool as the second screener in a reviewer pair or say it would overcome reliability concerns on its own (Introduction; no page number available). (LLM, conf=0.88)
Experimental — accuracy not yet measuredWhen using cross-validation, 11 studies adopted the 10-fold or 5 × 2-fold approach.
“When using cross-validation, 11 studies adopted the 10-fold or 5 × 2-fold approach [33,37,38,43,44,48,52,61,63,66,67].”
From Automation of systematic literature reviews: A systematic literature review (2021) · cites this paper as [61]
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- Authors
- Bekhuis, T., & Demner-Fushman, D.
- Affiliations
- University of Pittsburgh (US)
- Corresponding author
- Bekhuis, Tanja
- ORCID
- Bekhuis, Tanja
- Venue
- Artificial Intelligence in Medicine
- Publisher
- Elsevier BV
- Published
- 2012-07
- Volume
- 55
- Issue
- 3
- Pages
- 197-207
- ISSN
- 0933-3657 (ISSN-L)
- PMC
- PMC3393813
- OpenAlex
- W2063198586
- Cited by
- 70
- References
- 50
- Citations by year
- 2026: 1 · 2025: 4 · 2024: 7 · 2023: 3 · 2022: 4 · 2021: 6 · 2020: 7 · 2019: 3 · 2018: 5 · 2017: 5 · 2016: 9 · 2015: 11 · 2014: 2 · 2013: 3
- FWCI
- 1.41
- Type
- journal article
- Language
- en
- Open access
- green
- europepmc.org
- Locations
- Artificial Intelligence in Medicine (publishedVersion)
- PubMed (publishedVersion)
- Europe PMC (PubMed Central) (acceptedVersion)
- PubMed Central (acceptedVersion)
- Funders
- National Institute of Dental and Craniofacial Research (5 T15 LM/DE07059)
- U.S. National Library of Medicine (R00LM010943, K99LM010943)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Computer Science › Artificial Intelligence › Text and Document Classification Technologies
- Physical Sciences › Computer Science › Information Systems › Information Retrieval and Search Behavior
- Keywords
- non-randomized studies, full-text screening, systematic reviews, citation classification, machine learning classifiers, complement naive Bayes, k-nearest neighbors, n-gram features, information gain feature selection, classifier optimization
- MeSH terms
- Algorithms, Artificial Intelligence, Bayes Theorem, Humans, Medical Informatics, Review Literature as Topic, Biomedical Research, Data Mining, Support Vector Machine
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