Tuesday, January 29, 2013

Cardiology Society (non) Defines Key Entities for Cardiovascular Care

The American College of Cardiology (ACC) and the American Heart Association (AHA) are to be lauded for their goal of creating standard definitions of key terms for use in collecting scientific data.

However, their execution is--quite frankly--abysmal.

Here are some definitions they generated:

SexIndicate the patient's sex at birth as either male or female. Choose 1 of the following: Male Female
Date of birthIndicate the patient's date of birth.

These are NOT definitions at all.  We have been misled.  These are instructions, however obvious.  What did the ACC and AHA think someone might do when confronted with a data entry form asking for the patient's sex and date of birth?

For real definitions of sex and date of birth, and a standard way of recording them that requires no special data machinery specific to demographics, see a paper by Hogan et al. from the 2011 International Conference on Biomedical Ontology.  These definitions have been captured in the Demographics Application Ontology, available here.

But since the real goal is to capture data elements specific to the field of cardiology, perhaps it is too unfair to criticize their efforts on demographics.   Cardiologists, after all, are more concerned with the heart than the rest of the person.

Alas, although they do move from instructions to definitions, their definitions are poor.  They are circular, meaning that they use the words in the term to define the term:

Prior anginaHistory of angina before the current admission. “Angina” refers to evidence or knowledge of symptoms before this acute event described as chest pain or pressure, jaw pain, arm pain, or other equivalent discomfort suggestive of cardiac ischemia. Indicate if angina existed >2 wk before admission and/or within 2 wk before admission.
Average number of episodes of angina in the prior weekAverage number of distinct episodes of anginal pain that occurred in the last week before hospital admission or this visit

Furthermore, what if the patient is not being admitted to the hospital?  According to this definition, a clinician should not record "prior angina" if the patient had a history of angina prior to a clinic or emergency department visit.

The definition of "angina", alas, although promising, is ruined by the prefix "evidence or knowledge of".   If there is no evidence or knowledge of Mr. Smith's angina (perhaps he has no memory of it due to some mental disorder such as dementia), it still exists.  It also conflicts with the subsequent instruction to record the existence (not knowledge or evidence) of angina.

Furthermore, it really defines two data elements, despite being listed as one.  We are told to record existence (not knowledge or evidence) of angina before 2 weeks prior to admission (data element #1) and the existence (not knowledge or evidence) of angina within 2 weeks prior to admission (data element #2).

Thus the data element "prior angina" is also ambiguous.

The circularity of the definition of "average number of episodes of angina in the prior week" is self evident.  Note that now we are told that by "admission", the ACC and AHA probably in fact do intend to refer to outpatient encounters as well as inpatient ones.

Perhaps they should have stopped to define "admission", "visit", etc. first?  Well, if they had, it wouldn't have taken them long.  They could have adopted the definitions of these terms provided by the Ontology for General Medical Science, available here.

So we see that persons who are experts in a particular field of study, although necessary to the process of defining the terms they use, are not sufficient.

They should have consulted a good ontologist!

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