Rule of Logic

The Rule of Logic suggests certain conclusion based on the patient's symptoms, research results and previously made diagnoses. The conclusion may be either to suggest diagnosis (with certain probability), assign investigation or ask the patient about some symptom. Let us consider some examples of Rules of Logic.

IF [(Blood pressure systolic > 140 OR Blood pressure diastolic > 90) AND Blood cholesterol total > 200]
OR
[Arrhythmia AND Temperature(F) > 99 AND Not Flu infection]
THEN Assign Investigation: Echocardiography

The conclusion for this rule - is to do Investigation. This rule will suggest to do Echocardiography for every patient who either has got increased blood pressure and high cholesterol level at the same time or has got arrhythmia with increased temperature, providing this increased temperature is not caused by simple flu infection. Introducing of this rule does not mean that Echocardiography will be suggested only if conditions above are met. Other rules may suggest to do it for other conditions as well (for example, the other rule may assign this investigation if there are some known heart conditions, no matter what blood pressure or temperature are). What the rule in this example does - it expresses the opinion of certain specialist that in this case the Echocardiography should be definitely done. But it does not provide anything for other cases or conditions. As we can see, the rules can intersect with each other in both parameters they depend on and conclusion they make. When making Research for the patient the system will put them all together and make the final conclusion.

Another example

IF (Cough OR Wet nose OR Sore throat) AND Temperature(F) > 99 AND
(Joint pain AND Not Arthritis) AND Headache AND Eyes movement pain
THEN Make Diagnosis: Flu infection with 85% probability

This rule suggests the Flu infection as a diagnosis with 85% probability if conditions above are met. Note, it will check for the Joint pain but will sort out cases when this pain may be causes by Arthritis rather than by Flu infection. Once again it does not mean that Flu infection will be only diagnosed by the system if the patient medical records match all conditions of this rule. There may be other rules about Flu infection as well. For example, there may be rule, which would suggest Flu infection if there are only cold symptoms and high temperature. But in this case the probability will be much less as these symptoms may well indicate just simple cold, which is not caused by a Flu virus.

This system allows Rule of logic to be a logical expression of any complexity and length. Formally the rule of logic can be expressed by formula:

          R(P 1, P 2, ..., P n , D 1 , D 2 , ..., D n ) -> D or I or S,

where
      R - Rule of logic
      D - Diagnosis
      P - Parameter (either Symptom or Research result)
      I - Investigation
      S - Symptom

See also: Rule List, Rule Edit, Conclusion