Schulz Stefan, Markó Kornél, Suntisrivaraporn Boontawee
Institute of Medical Biometry and Medical Informatics, University Medical Center, Freiburg, Germany.
BMC Med Inform Decis Mak. 2008 Oct 27;8 Suppl 1(Suppl 1):S9. doi: 10.1186/1472-6947-8-S1-S9.
Definitory expressions about clinical procedures, findings and diseases constitute a major benefit of a formally founded clinical reference terminology which is ontologically sound and suited for formal reasoning. SNOMED CT claims to support formal reasoning by description-logic based concept definitions.
On the basis of formal ontology criteria we analyze complex SNOMED CT concepts, such as "Concussion of Brain with(out) Loss of Consciousness", using alternatively full first order logics and the description logic EL.
Typical complex SNOMED CT concepts, including negations or not, can be expressed in full first-order logics. Negations cannot be properly expressed in the description logic EL underlying SNOMED CT. All concepts concepts the meaning of which implies a temporal scope may be subject to diverging interpretations, which are often unclear in SNOMED CT as their contextual determinants are not made explicit.
The description of complex medical occurrents is ambiguous, as the same situations can be described as (i) a complex occurrent C that has A and B as temporal parts, (ii) a simple occurrent A' defined as a kind of A followed by some B, or (iii) a simple occurrent B' defined as a kind of B preceded by some A. As negative statements in SNOMED CT cannot be exactly represented without a (computationally costly) extension of the set of logical constructors, a solution can be the reification of negative statments (e.g., "Period with no Loss of Consciousness"), or the use of the SNOMED CT context model. However, the interpretation of SNOMED CT context model concepts as description logics axioms is not recommended, because this may entail unintended models.
关于临床程序、检查结果和疾病的确切表述构成了一个正式建立的临床参考术语的主要优势，该术语在本体论上合理且适用于形式推理。SNOMED CT声称通过基于描述逻辑的概念定义来支持形式推理。
基于形式本体标准，我们使用全一阶逻辑和描述逻辑EL对复杂的SNOMED CT概念，如“伴有（或不伴有）意识丧失的脑震荡”进行分析。
典型的复杂SNOMED CT概念，包括有或没有否定词的，都可以用全一阶逻辑来表达。否定词在SNOMED CT所基于的描述逻辑EL中无法正确表达。所有其含义暗示时间范围的概念可能会有不同的解释，在SNOMED CT中这些解释往往不明确，因为其上下文决定因素没有明确说明。
复杂医学事件的描述是模糊的，因为相同的情况可以被描述为：（i）一个具有A和B作为时间部分的复杂事件C；（ii）一个被定义为某种A接着是一些B的简单事件A'；或者（iii）一个被定义为某种B之前是一些A的简单事件B'。由于在不（以计算成本高昂的方式）扩展逻辑构造器集合的情况下，SNOMED CT中的否定陈述无法准确表示，一种解决方案可以是对否定陈述进行具体化（例如，“无意识时期”），或者使用SNOMED CT上下文模型。然而，不建议将SNOMED CT上下文模型概念解释为描述逻辑公理，因为这可能会导致意外的模型。
