Observation vs Condition

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From the perspective of HL7, the great majority of clinical information falls under the category of "observation". The distinction between general observations (such as signs, symptoms, blood pressure, body temperature, body weight, height, etc), imaging/laboratory test results, problems, diagnosis is achieved through the use of vocabularies.

Extensive debates between clinicians and FHIR team occurred over a period of at least 3 workgroup meetings on whether "problem" and "diagnosis" are structurally different from modelling perspective from the concept - "observation".

Eventually, the FHIR team agreed to create a "condition" FHIR resource to represent "problem" and "diagnosis", and the "observation" FHIR resource to represent general observation findings.

However the question of whether there is any difference between "observation" and "condition" never goes away and has been raised many times since.

The clinical and FHIR communities agree that there is a high need to clearly define these concepts and determine their differentiating characteristics from the clinical and engineering perspectives.


  • Stephen Chu
  • Russ Leftwich
  • Rob Hausam
  • Elaine Ayres

Definitions and Examples

Observation and Clinical Observation

  • Observation:
- Dictionary definition: "the act of watching somebody/something carefully for a period of time, especially to learn something"
- Source: http://www.oxfordlearnersdictionaries.com/definition/english/observation

  • Clinical:
- Dictionary definitions:
- Relating to the bedside treatment of a patient or to the course of the disease
- Relating to the observed symptoms and course of a disease
- Source: http://medical-dictionary.thefreedictionary.com/clinical

  • Clinical observation:
- Definition: "the act of watching and obtaining information about a patient's clinical status including signs, symptoms, and course of a disease"

  • Examples of clinical observations:
- "Clinical observations include estimation of haemoglobin-oxygen saturation (SpO2, pulse oximetry), oxygen therapy, respiratory rate, heart/pulse rate, blood pressure (systolic, diastolic and mean), temperature (including measurement method), sedation and pain. In certain clinical circumstances further observations (for example neurological) may be required"
- Source: http://www.rch.org.au/rchcpg/hospital_clinical_guideline_index/Observation_and_Continuous_Monitoring/

Condition/Health Condition

  • Condition:
Dictionary Definitions:
- Condition is defined as:
(1) a particular mode of being of a person or thing; existing state; situation with respect to circumstances
(2) state of health
(3) a person's or animal's state of health or physical fitness
- Source: http://dictionary.reference.com/browse/condition
- Source: http://www.oxforddictionaries.com/definition/english/condition
HL7 FHIR/PCWG Definition:
- "A condition is a clinician’s assessment and assertion of a particular aspect of a person’s state of health. Examples of condition include problems, diagnoses, concerns, issues"

  • Synonymous Concepts:
- A number of concepts are used synonymously with "condition"/"health condition"
- Examples:
- long-lasting health condition (also called a chronic illness)
- Source: http://kidshealth.org/teen/your_mind/problems/deal_chronic_illness.html
- Under the FMLA (The Family and Medical Leave Act, USA) a serious health condition is an illness, injury, impairment or physical or mental condition
- http://www.shrm.org/templatestools/hrqa/pages/howemployeemedicalabsencequalifiesforfmlaleave.aspx

  • Examples of health/medical conditions:
- Tuberculosis, poliomyelitis, Non-Hodgkin's lymphoma, Diabetes mellitus type 1, malnutrition, obesity
- Source: http://www.health.gov.au/internet/publications/publishing.nsf/Content/ageing-acfi-userguide-feb2013-toc~ageing-acfi-userguide-feb2013-app1

Scope and Use


  • Place holder for contents


  • "Condition" is used to record detailed information about a clinician’s assessment and assertion of a particular aspect of a patient’s state of health. It is intended for use to record information about:
- a disease/illness identified from application of clinical reasoning over the pathologic and pathophysiologic findings (diagnosis), or
- identification of health issues/situations that require ongoing monitoring and/or management (health issue/concern), or
- identification of health issues/situations considered harmful, potentially harmful and required to be investigated and managed (problems).
  • It may also be used to record certain health state of a patient which does not normally present negative outcome (until complications are predicted or detected), e.g. pregnancy. Examples of complications of pregnancy include: hyperemesis gravidarum, preeclampsia, eclampsia, which are captured as problems/diagnoses.
  • It may be referenced by other resources as “reasons” for an action (e.g. prescription, procedure, DiagnosticOrder, etc)
  • It is not to be used to record information about signs and symptoms that are typically captured using the “observation” resource; although in some cases a persistent symptom, e.g. fever, headache may be captured as a condition before a definitive diagnosis can be discerned by a clinician.
  • The "Condition" FHIR resource also specifically excludes “AllergyIntolerance” and “Adverse Reactions” as those are handled with their own resources

Information/data elements collected for Observation and Condition

There are common data elements/components that are collected for both "observation" and "condition". These are the context related information such as:

- Patient details
- Observer/documenter (this can be the same or different person)
- Event/encounter details (including Event/encounter type, location, date and time of encounter/event)

There are also "observation" and "condition" specific data elements/components.

A number of these data elements/components can be considered as "differentiating attributes" that differentiate "observation" from "condition.

  • Observation specific data elements/components:
- Datetime start and DateTime end
- These values apply to sign and symptom observation observation types
o For example: cough, fever, pain, swelling, rash, dyspoenia, cyanosis, 24 hours urine output, panic attack, etc
- For other observations it is uncommon/not very useful to record the start and end values
o For example: temperature, heart/pulse rate, respiratory rate, body weight, height, head circumference, pulse oximetry, etc
- Observation Name/Description
- Identifies the name of the observation/measurement
o Examples: cough, fever, systolic blood pressure, spO2, sputum colour
- Observation value
- Identifies the result of the observation/measurement in numeric or descriptive value
o Examples: 37C (temperature), 180cm (body height), blood stained (sputum/urine colour)
- Body site/anatomical location
- Describes, where applicable, the body site/anatomical location where the observation/measurement was made or applied
o Example: right upper abdominal quadrant (pain, tenderness); trunk and legs (petechial skin rash)
- Patient State
- Identifies/describes the physical condition of the patient that may influence the interpretation of the observation/measurement
o Examples: standing, sitting, clothing/shoes on, on room air, on 2L/min O2
- Confounding Factors
- Identifies/describes extraneous/incidental factors that impact on interpretation of the observation or measurements
o Examples: patient in pain, confused, restless
- Note: the data elements/components listed above are not intended to be exhaustive for "observation". There are other that are not included in the above list.

  • Condition specific data elements/components:
- Condition Name/Description:
- Identifies/describes the name of the problem/diagnosis/condition
o Examples: Type 2 Diabetes Mellitus, Fracture scaphoid, Ebola heamorrhagic fever, migraine, acute pancreatitis, pregnancy
- DateTime of onset
- Identifies the date and optionally time the condition/problem was first identified
- Age at onset
- Identifies the age of the patient at which the condition/problem was first identified
- DateTime of resolution/remission
- Identifies the date and optionally the time the condition/problem was considered resolved or went into remission
- Age at remission
- Identifies the age of the patient at which the condition was considered resolved or went into remission
- Body site/anatomical location
- identifies/describes the body site or anatomical location affected by the condition/problem, where the body site or anatomical location information is not a component of the condition/problem description
o Examples: right front lobe (cranial tumour); right lower lobe (pulmonary embolism)
- Clinical stage/grade
- Identifies/describe the clinical stage or grading of a condition/problem
o Example: clinical staging of cancer (TNM staging); NY Heart Association Functional Classification of Heart Failure
- Evidence
- Describes/identifies relevant supporting pathological/pathophysiological information that underpins the clinical reasoning leading to the recognition of a clinical or health condition
o Examples: signs, symptoms, diagnostic test findings
- Note: the data elements/components listed above are not intended to be exhaustive for "condition". There are other that are not included in the above list.

Differentiating Characteristics

There are clear clinical semantics that separate "Observation" (in general) from "Condition".

  • Clinical differentiation:
- Clinical observation is the performance of measurements on a patient or patient specimen (or any objects that the patient is exposed to) and the data collected through the measurements
o the measurements can be simply watching the patient, or performing comprehensive or focused physical examination on and questioning of the patient, or performed using instruments on the patient or patient specimens/environments, etc
- Condition: determining that the patient has certain condition requires the processes of:
o clinical observation
o clinical reasoning
o arriving at a clinical judgement/decision based on pathological and pathophysiological evidences

The challenge is in identifying a set of differentiating characteristics from the modelling/engineering perspectives.


  • Target: this is the subject (or object) of the observation
- The target of a clinical observation may be:
o the patient
o specimen(s) obtained from the patient
o the environment or environmental factors to which the patient is exposed
o substance or object (including animals) to which the patient is exposed
- The target of an observation in general (not clinical specific)
o this can be any subject/object of interest, not necessarily a patient or patient related


  • Target:
- The target of a condition (e.g. pregnancy, Type 2 DM) is always a person/patient affected by the condition

  • Differentiating attributes:
- Course: a condition may run through a course over time, e.g. from acute, to chronic, to acute on chronic/acute exacerbation, to end stage
- Stage/Grade: many chronic conditions and cancer in particular may be assigned clinical stage or grades
- Example 1: Severity grading of liver injury
1+, Mild: Raised serum aminotransferase or alkaline phosphatase levels or both, but total serum bilirubin <2.5 mg/dL and no coagulopathy (INR <1.5)
2+, Moderate: Raised serum aminotransferase or alkaline phosphatase levels or both and total serum bilirubin level >2.5 mg/dL or coagulopathy (INR >1.5) without hyperbilirubinemia
3+, Moderate to Severe: Raised serum aminotransferase or alkaline phosphatase levels and total serum bilirubin level >2.5 mg/dL and hospitalization (or preexisting hospitalization is prolonged) because of the drug induced liver injury
4+, Severe: Raised serum aminotransferase or alkaline phosphatase levels and serum bilirubin >2.5 mg/dL and at least one of the following:
- Prolonged jaundice and symptoms beyond 3 months, or
- Signs of hepatic decompensation (INR >1.5, ascites, encephalopathy), or
- Other organ failure believed to be related to drug induced liver injury
5+, Fatal: Death or liver transplantation for drug induced liver injury
- Example 2: Colorectal cancer staging:
- Tumour Stage (AJCC 7th edition): ypT3, pN1b, cM0
- Stage group: IIIB
- Reference:
- AJCC/UICC colorectal cancer TNM classification

Relevant Documents and Meeting Minutes

  • Meeting Minutes:
- Observation vs Condition Conference Call minutes 2014-10-27

  • Observable Model Slide Decks (contribution from Dr Rob Hausam):
- SNOMED-CT and LOINC Observables 2014-03-13 Part-1
- SNOMED-CT and LOINC Observables 2014-03-13 Part-2
- SNOMED-CT and LOINC Observables 2014-03-13 Part-3

Further Discussions

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