Acquired <finding or disorder)

IHTSDO-1059 - Getting issue details... STATUS

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Approvals 

1. Content Issue Summary 

a. Summary of issue 

There are currently approximately 770 (20180131 release)  concepts in the Clinical findings and Disease hierarchy that contain the word "acquired" in the FSN.  These are used clinically to differentiate clinical conditions that may be either congenital or acquired later in life.  Of these, 445 are primitive and 275 are sufficiently defined. There are a number of issues related to the presence of these primitive concepts: 

• Many of the existing terms have been modeled using "Acquired X (morphologic abnormality)" concepts, which allows them to be sufficiently defined, but results in creation of additional morphology concepts that only differ in the period of life in which they appear. This is analogous to the "Congenital X" morphologies that are being inactivated through remodeling of the Congenital disease subhierarchy. 
• "Acquired" and "Congenital" are not morphologies, but timeframes.  We currently do not have a way of denoting "All periods of life after birth" like we do for "Congenital".
• The ability to define acquired disorders might also open the door that all disorders that are normally acquired after birth have an OCCURRENCE relationship added, which seems to be “overmodeling”.  The "Acquired deformity" morphology concepts are incomplete and a suboptimal way to address temporality. 
• Some diseases, especially those appearing in the neonatal period, may actually be later manifestations of congenital conditions.
• The application of the proposed modeling pattern would only be applied in situations where there is a specific need to differentiate between congenital and acquired conditions of the same type.

b. Related content projects and requests 

2. Analysis of Issue 

Acquired conditions are those which originate and manifest after birth.  Since this relates to a period of life as opposed to a specific process or structure, all diseases that occur after birth may be considered to be acquired.  According to the American medical association, the periods of life that are included under the "postnatal period" include all periods after birth including the neonatal or immediate postpartum period. Diseases that manifest during the neonatal period of life are challenging since the inciting cause may be present at birth, the clinical manifestation may take a day or two to appear (e.g. Neonatal isoimmune neutropenia). 

Three alternatives have been considered:

• Create an intermediate primitive grouper - "Acquired disorder" that would allow subtypes to be fully defined under. These would also classify under the appropriate parent term related to the disorder.
• Create a "period of life" subtype that included all periods except "fetal, congenital, and neonatal(?) (substantial testing of impacts would be needed)
• Create a set of "Acquired X (morphologic abnormalities)" to support definition of acquired disorders.

There are challenges with using period of life as a way to classify these as age ranges differ among juridictions. There is also the issue that the designation of a period of life in an FSN does not always reflect the period of life in which the orign and manifestation are identified. For example, hereditary diseases often manifest later in life. Would these be considered "Congenital", "Acquired", both? What do we mean when we say "acquired"?

It would be prudent to limit the use of the period of life grouper to necessity, i.e. for only those disease where the FSN specifies "acquired" or a need to specify a distinction between congenital and acquired forms of a disorder. What would be the  advantage of a top level grouper "Acquired disorder"? The challenge is how to represent the acquisition/origin of the trait as opposed to the clinical manifestation of the trait, or if that distinction is needed.  For non-semantically decomposable FSNs, it is more important to get the modeling correct than change the idiom. 

3. Additional issues identified  

This slution does not adequately address concepts containing the term "juvenile" as that term is used to represent the clinical manifestation of a disorder at a very broad range of life periods.  There is an inactive concept  282035009 -    Juvenile (qualifier value), which I suspect was inactivated due to the variability in determining which more specific life periods it encompasses.

Many of the affected concepts are not modeled according to the pattern shown in the solution section below. These will be editied to conform to the proposed pattern.

Concepts using the term "neonatal" much be indiviudally and carefully curated to ensure that the correct origin of the disorder is assigned.

4. Solution 

• A new qualifier value of "Post-natal" will be created to aggregate the periods of life that would be used to define "Acquired" conditions.
• Move the following concepts under “Postnatal period”:
  • Adolesence
  • Adulthood
  • Childhood
  • Infancy
  • Old age
• All concepts that current explicitly state "acquired" in their FSN would have a new relationship OCCURRENCE = Post-natal period (qualifier value) added to the defining relationship group(s), if an OCCURRENCE relationship does not already exist.  This will allow many of the currently primitive concepts to become sufficiently defined, resulting in a richer set of inferences.
• When revising modeling of acquired disorders, remove any “Acquired” morphologies and replace with general parent morphology.  E.g. Replace “acquired deformity” with “deformity”.

The general pattern for revising the affected concepts is shown in the diagram below: