  Purpose: This study aims to develop a novel approach to extracting and
measuring uncertain biomedical knowledge from scientific statements.
Design/methodology/approach: Taking cardiovascular research publications in
China as a sample, we extracted the SPO triples as knowledge unit and the
hedging/conflicting uncertainties as the knowledge context. We introduced
Information Entropy and Uncertainty Rate as potential metrics to quantity the
uncertainty of biomedical knowledge claims represented at different levels,
such as the SPO triples (micro level), as well as the semantic type pairs
(micro-level). Findings: The results indicated that while the number of
scientific publications and total SPO triples showed a liner growth, the novel
SPO triples occurring per year remained stable. After examining the frequency
of uncertain cue words in different part of scientific statements, we found
hedging words tend to appear in conclusive and purposeful sentences, whereas
conflicting terms often appear in background and act as the premise (e.g.,
unsettled scientific issues) of the work to be investigated. Practical
implications: Our approach identified major uncertain knowledge areas, such as
diagnostic biomarkers, genetic characteristics, and pharmacologic therapies
surrounding cardiovascular diseases in China. These areas are suggested to be
prioritized in which new hypotheses need to be verified, and disputes,
conflicts, as well as contradictions to be settled further.
