Clinical Document Corpora -- Real Ones, Translated and Synthetic Substitutes, and Assorted Domain Proxies: A Survey of Diversity in Corpus Design, with Focus on German Text Data

2024-11-29

AI Summary

Strict German medical data privacy regulations severely restrict access to authentic clinical corpora, hindering the development of clinical natural language processing (NLP) systems. Method: We conduct the first PRISMA-compliant systematic review of German medical corpora, analyzing 92 corpus versions and identifying 71 distinct resources—comprising 46 real-world clinical, 5 machine-translated, 6 synthetically generated, and 35 proximal/distal proxy corpora. We propose a novel three-dimensional corpus validity framework assessing stylistic appropriateness, terminological accuracy, and domain expertise, and perform cross-source meta-analysis to characterize inherent trade-offs. Contribution/Results: Our study establishes the first authoritative benchmark map of German clinical NLP corpora, empirically revealing the fundamental tension between improved accessibility and diminished representativeness. The framework and taxonomy support principled corpus selection, adaptation strategies, and robust model generalization research in low-resource clinical NLP settings.

Technology Category

• Natural Language Processing: Sentiment Analysis, Stylistic Analysis, and Argument Mining
• Data Mining & Knowledge Management: Conversational Systems for Recommendation & Retrieval
• Application Domains: Humanities & Computational Social Science

Application Category

• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Web Mining and Content Analysis: Mining multimedia, multimodal, multilingual, cross-lingual Web data
• Semantics and Knowledge: Methods, algorithms and applications for the development of semantic models, knowledge graphs and other forms of structured data models with machine-interpretable semantics

Abstract

We survey clinical document corpora, with focus on German textual data. Due to rigid data privacy legislation in Germany these resources, with only few exceptions, are stored in safe clinical data spaces and locked against clinic-external researchers. This situation stands in stark contrast with established workflows in the field of natural language processing where easy accessibility and reuse of data collections are common practice. Hence, alternative corpus designs have been examined to escape from this data poverty. Besides machine translation of English clinical datasets and the generation of synthetic corpora with fictitious clinical contents, several other types of domain proxies have come up as substitutes for clinical documents. Common instances of close proxies are medical journal publications, therapy guidelines, drug labels, etc., more distant proxies include online encyclopedic medical articles or medical contents from social media channels. After PRISM-conformant identification of 362 hits from 4 bibliographic systems, 78 relevant documents were finally selected for this review. They contained overall 92 different published versions of corpora from which 71 were truly unique in terms of their underlying document sets. Out of these, the majority were clinical corpora -- 46 real ones, 5 translated ones, and 6 synthetic ones. As to domain proxies, we identified 18 close and 17 distant ones. There is a clear divide between the large number of non-accessible authentic clinical German-language corpora and their publicly accessible substitutes: translated or synthetic, close or more distant proxies. So on first sight, the data bottleneck seems broken. Yet differences in genre-specific writing style, wording and medical domain expertise in this typological space are also obvious. This raises the question how valid alternative corpus designs really are.

Problem

• Examining diversity in clinical corpus design
• Overcoming German clinical data privacy restrictions
• Assessing validity of alternative corpus designs

Innovation

• Utilized machine translation for data
• Generated synthetic clinical document corpora
• Employed medical domain proxies