# Electronic Health Records and Context
Electronic Health Records (EHRs) use diverse data entry models to support various clinical use cases. Each model has specific terminology and information structure requirements. To ensure the captured information is interoperable and meaningful beyond its initial use, it is essential to design a comprehensive context representation model.
## Clinical Data Entry Scenarios and Context Representation Challenges
### Free Text Entry
#### Interpretation
* Accurate interpretation depends on how each sentence is phrased.
* Ignoring any part of the text may lead to misinterpretation.
* Computerized processing may be possible using Natural Language Processing (NLP), sometimes generating structured coded data for reporting and analysis.
#### Example: Admission Note
{% code overflow="wrap" %}
```
Acute 161972006 | central chest pain (finding)|.
No past history of 56265001 | heart disease (disorder)| or 50043002 | Disorder of respiratory system (disorder)|.
Hiatus hernia 84089009 | hiatus hernia| was diagnosed 5 years ago.
Treats 162031009 | indigestion (finding)| with 3402011000001103 | Generic Gaviscon 500mg chewable tablets sugar free (product)|.
Father died of myocardial infarction at age 57. 160274005 | No family history diabetes (situation)|.
Says their cousin has chest problems but is not sure if this is Asthma.
Working diagnosis: possible myocardial infarction but maybe reflux gastritis.
```
{% endcode %}
**Note after investigation**
```
Diagnosis of myocardial infarction.
```
### Structured Form with Headed Sections
#### Interpretation
* Interpretation depends on section headings and terms/phrases under each heading.
* Computerized interpretation possible if section meanings and entries are coded.
#### Example Medical Case Summary
{% code title="Presenting Symptoms" %}
```
Acute central chest pain
```
{% endcode %}
{% code title="Past Medical History" %}
```
No known heart or lung disease
Hiatus hernia
```
{% endcode %}
{% code title="Family History" %}
```
Father: Myocardial infarction (died at 57)
No family history of diabetes mellitus
Uncertainty about family history of asthma
```
{% endcode %}
{% code title="Differential Diagnosis (on admission)" %}
```
Myocardial infarction
Reflux esophagitis
```
{% endcode %}
{% code title="Final Diagnosis" %}
```
Myocardial infarction
```
{% endcode %}
### Structured Form with Headed Sections and Prompts
#### Interpretation
* Depends on section heading, question/data label, and values entered.
* Computerized interpretation is possible with appropriate codes and values.
#### Example
{% code title="Past Medical History" %}
```
Heart disease: Yes No
Lung disease: Yes No
Gastrointestinal disease: Yes No
Hiatus hernia
```
{% endcode %}
{% code title="Family History" %}
```
Heart disease: Yes No Unknown
Diabetes mellitus: Yes No Unknown
Chronic lung disease: Yes No Unknown
```
{% endcode %}
{% code title="Vital Signs" %}
```
Heart rate: 85 /min
Respiratory rate: 24 /min
Temperature: 37.2 °C
```
{% endcode %}
{% code title="Diagnosis (on admission)" %}
```
Myocardial infarction: Confirmed Possible Excluded
Reflux esophagitis: Confirmed Possible Excluded
```
{% endcode %}
{% code title="Diagnosis (after investigation)" %}
```
Myocardial infarction: Confirmed Possible Excluded
Reflux esophagitis: Confirmed Possible Excluded
```
{% endcode %}
An EHR may emulate traditional paper-based structures for data entry and display. However, unlike paper records, electronic systems store data in a common logical structure, independent of UI format. This allows for flexible display, reporting, and analysis.
Different entry techniques suit different clinical situations—e.g., a checklist for common history items or a detailed form for a specific diagnosis. Paper records may differ structurally but contain similar information. In contrast, EHRs can map diverse UI formats to a unified structure, as illustrated in the diagram below.
Accurate interpretation of data from various input methods requires systems to capture and consistently apply context—e.g., differentiating between confirmed vs. possible diagnoses, or personal vs. family history.
**Example of Mapping from Different User Interface Examples to a Common Data Structure**
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