Abstract text (incl. figure legends and references)

Background:

In clinical practice, headache presentations may fit more than one ICHD3 diagnoses. This project seeks to exhaustively list all logically consistent "codiagnoses" according to ICHD3 criteria. We limit our project to cases where only two diagnoses are involved.

Methods:

We included the ICHD3 criterias for "Migraine" (1.1, 1.2, 1.3), "Tension-type headache" (2.1, 2.2, 2.3, 2.4), "Trigeminal autonomic cephalalgias" (3.1, 3.2, 3.3, 3.4, 3.5), as well as all "Other primary headache disorders". We excluded "Complications of migraine"(1.5) and "Episodic syndrome that may be associated with migraine" (1.6) since these diagnoses require codiagnoses of migraine as first assumption. We also excluded "probable" diagnosis criteria.

Each phenotype in the above criteria is assigned an unique prime number. We then encoded each ICHD3 criteria into integers, call "criteria representations", through multiplication in a list format. (See Abstract ID-9) "Codiagnoses representations" are generated by multiplying all possible pairings of criteria representations.

To eliminate logical inconsistent codiagnses, we manually encode a list of logically inconsistent phenotypes through multiplication: For example, headache lasting "seconds" would be logically inconsistent with "headache lasting hours"; the prime representation for both are multiplied together. We called this list the "inconsistency representations".

All codiagnoses representation divisible by any inconsistency representations are filtered out, generating a list of codiagnoses represenation that are logically consistent. This list is then translated back into ICHD3 diagnoses.

Results:

A total of 103 phenotypes are encoded with 99 pairs being inconsistent. There are 128 possible codiagnoses. We will present these in the meeting.

Conclusions:

Codiagnoses are possible but uncommon. Prime representation of ICHD3 criteria provides a powerful way to analyze ICHD3 as numerical data.