The concept's class provides a useful way to narrow down the scope of the information that the concept is intended to capture.  In this way, the class is helpful for data extraction.  This classification details how a concept will be represented (i.e. as a question or an answer) when the information is stored.  OpenMRS contains several default classes to use when defining concepts, but implementation sites may also create additional custom concept classes for use. 

This wiki page provides a helpful diagram to understand the use of concept classes.

OpenMRS Concept Classes

Test

lab tests (e.g. CD4 Count) or physical exam maneuver (e.g. Babinski)

Procedure

spinal tap, lumbar puncture, etc.

Drug

medications, prescriptions and over the counter

Diagnosis

defined medical conclusion (ie. diabetes, AIDS)

Finding

physical or exam findings (ie. shortness of breath, systolic murmur, LLL infiltrate)

Anatomy

body part (ie. right arm, frontal lobe, abdomen)

Question

query to which there are either open-ended or coded responses

LabSet

a group of several test concepts (ie. I-Stat Chem8+)

MedSet

a group of several medications (ie. cardiac drugs)

ConvSet

a group of concepts, typically questions, assembled for convenience (ie. vital signs)

Misc

This is normally used as a coded answer. Sometimes it would be a general descriptions of location or rankings (ie. left, severe, positive, unknown)

Symptom

any sign or indication of a possible conclusion (ie. chills, fever, increased heart rate)

Symptom/Finding

any sign or indication, not specifically linked to one conclusion

Specimen

a sample of any larger part (ie. tissue, blood sample)

Misc Order

orders typically not utilized by the organization

Additional Classes

The following 3 classes are used by Partners In Health and possibly other organizations. This functionality will be fixed with future OpenMRS releases (OpenMRS 1.9+).

Program

a specific plan, or set of plans, that a patient may be enrolled (ie. HIV program, Food assistance program)

Workflow

a process, as described by the organization (ie. group, treatment status)

State

a unique status for a workflow (ie. Group R which meets on Tuesday at 10am, On ARVS)

Subtleties between Concept Classes

• Symptom, Finding, and Diagnosis:  A finding is something a healthcare practitioner notes on examination, a symptom is something a patient complains of, and a diagnosis is a label made after findings, symptoms, and tests are considered.  The differences are subtle, but important to distinguish between. Chest pain is not a finding for example, it's a symptom. Anemia is not a finding or a symptom, it's a diagnosis.