Compound Expression Constraints
Expression constraints can be built up from smaller parts using conjunction (i.e. AND) and disjunction (i.e. OR). The simplest example of this is where the conjunction or disjunction is used between two simple expressions. For example, the following expression constraint is satisfied only by clinical findings which are both a disorder of the lung and an edema of the trunk. This gives the same result as a mathematical intersection between the set of 19829001 | Disorder of lung| descendants and the set of 301867009 | Edema of trunk| descendants.
Please note that all keywords are case insensitive, so the following two expression constraints are equivalent to the above:
The next expression constraint is satisfied only by clinical findings which are either a disorder of the lung or an edema of the trunk. This gives the same result as a mathematical union of the set of 19829001 | Disorder of lung| descendants and the set of 301867009 | Edema of trunk| descendants. For this reason, an OR operator will usually allow more valid clinical meanings than an AND operator.
Conjunction and disjunction operators may also be combined with the use of the 'member of' function, as shown below:
This expression constraint is satisfied only by concepts that belong to the 19829001 | Disorder of lung| hierarchy and are also members of the 700043003 | Example problem list concepts reference set| .
When more than one conjunction or more than one disjunction is used, round brackets can be optionally applied. For example, the following expression constraints are all valid and equivalent to each other:
Attribute Conjunction and Disjunction
Conjunction and disjunction may be used within refinements in a variety of ways. The most common way of using these operators in a refinement is to define the conjunction or disjunction of individual attributes.
For example, the expression constraint below, in which the comma between the two attributes represents conjunction, is satisfied only by clinical findings which have both a finding site of pulmonary valve structure (or subtype) and an associated morphology of stenosis (or subtype).
For example, the following expression constraint is not valid:
Attribute Group Conjunction and Disjunction
Similarly, conjunction and disjunction may be defined between attribute groups. The following expression constraint is satisfied only by clinical findings which either have a finding site of pulmonary valve structure (or subtype) and an associated morphology of stenosis (or subtype), OR have a finding site of right ventricular structure (or subtype) and an associated morphology of hypertrophy (or subtype).
{ 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,
116676008 |Associated morphology| = << 415582006 |Stenosis| } OR
{ 363698007 |Finding site| = << 53085002 |Right ventricular structure| ,
116676008 |Associated morphology| = << 56246009 |Hypertrophy| }
Attribute Value Conjunction and Disjunction
Conjunction and disjunction can also be applied to attribute values. The example below is satisfied only by members of the adverse drug reactions reference set for GP/FP health issue, which have a causative agent that is either a subtype of pharmaceutical / biologic product or a subtype of substance.
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