The Informatics for Integrating Biology and the Bedside (i2b2) is one of the sponsored initiatives of the NIH Roadmap National Centers for Biomedical Computing (http://www.bisti.nigh.gov/ncbc). One of the goals of i2b2 is to provide clinical investigators broadly with the software tools necessary to collect and manage project-related clinical research data in the genomics age as a cohesive entity – a software suite to construct and manage the modern clinical research chart. The i2b2 hive is a set of cells or modules that have a common messaging protocol that allow the cells to interact using web services and XML messages.

i2b2 Cell Messaging #

All cells in the i2b2 hive must communicate using standard i2b2 XML messages. This message specifies certain properties that are common to cells and essential to the administration tasks associated with sending, receiving and processing messages.

All requests are sent using a tag and responses are returned using a tag. The same tag is used for both. The is used for requests but may optionally be echoed back in the response. The response must include a .

The XSD specification of the i2b2 message permits individual cells to add cell-specific XML in the tag. This cell-specific XML need not extend the i2b2 message schema since the i2b2 schema will allow insertion of tags from any namespace into the tag.

The following image illustrates the basic top-level elements contained within the request and response messages.

i2b2 XML Schema Definitions #

The i2b2 XML schema consists of three XSD files:

i2b2.xsd #

The i2b2.xsd schema is not used directly to create i2b2 messages, but is included in the i2b2_request.xsd and the i2b2_response.xsd. It defines the tag.

i2b2_request.xsd #

The i2b2_request.xsd schema is used for validating i2b2 request messages. It defines the tag, which includes the tag.

i2b2_response.xsd #

The i2b2_response.xsd schema is used for validating i2b2 response messages. It defines the tag, which includes the tag.

Patient Data Object (PDO) #

The Patient Data Object is a representation of patient data.

PDO XML Schema Definitions #

The Patient Data Object (PDO) XML schema consists of three XSD files:

i2b2_PDO.xsd #

The i2b2_PDO.xsd schema is used for validating a PDO and defines a tag.

i2b2_PDO_fields.xsd #

The i2b2_PDO_fields.xsd schema is not used directly to validate a PDO but it is included in the i2b2_PDO.xsd schema. It defines different PDO building blocks.

i2b2_PDO_types.xsd #

The i2b2_PDO_types.xsd schema is not used directly to validate a PDO but it is included in the i2b2_PDO_fields.xsd schema. It defines basic data types that are reused.

Example Object #

   download_date=”2006-05-04T18:13:51.0Z”
   import_date=”2006-05-04T18:13:51.0Z”
   sourcesystem_cd=”sourcesystem_cd0″
   upload_id=”upload_id0″>
       event_id0
       patient_id0                                    2006-05-04T18:13:51.0Z
       2006-05-04T18:13:51.0Z

              download_date=”2006-05-04T18:13:51.0Z”
       import_date=”2006-05-04T18:13:51.0Z”
       sourcesystem_cd=”sourcesystem_cd3″
       upload_id=”upload_id3″>
           concept_path0
           concept_cd0
           name_char0





              download_date=”2006-05-04T18:13:51.0Z”
       import_date=”2006-05-04T18:13:51.0Z”
       sourcesystem_cd=”sourcesystem_cd6″ upload_id=”upload_id6″>
          observer_path0
          observer_cd0
          name_char3




                                download_date=”2006-05-04T18:13:51.0Z”
           import_date=”2006-05-04T18:13:51.0Z”
           sourcesystem_cd=”sourcesystem_cd9″
           upload_id=”upload_id9″ source=”HIVE”>patient_id3                       update_date=”2006-05-04T18:13:51.0Z”
           download_date=”2006-05-04T18:13:51.0Z”
           import_date=”2006-05-04T18:13:51.0Z”
           sourcesystem_cd=”sourcesystem_cd10″
           upload_id=”upload_id10″>patient_map_id0



                      download_date=”2006-05-04T18:13:51.0Z”
           import_date=”2006-05-04T18:13:51.0Z”
           sourcesystem_cd=”sourcesystem_cd15″
           upload_id=”upload_id15″>event_id3
                      patient_id_source=”HIVE” status=”status7″
           update_date=”2006-05-04T18:13:51.0Z”
           download_date=”2006-05-04T18:13:51.0Z”
           import_date=”2006-05-04T18:13:51.0Z”
           sourcesystem_cd=”sourcesystem_cd16″
           upload_id=”upload_id16″>event_map_id0



                 download_date=”2006-05-04T18:13:51.0Z”
       import_date=”2006-05-04T18:13:51.0Z”
       sourcesystem_cd=”sourcesystem_cd21″
       upload_id=”upload_id21″>
           patient_id12            param3            param3            param3            param3            param3            param3            param3            param3            param3            param3


              download_date=”2006-05-04T18:13:51.0Z”
       import_date=”2006-05-04T18:13:51.0Z”
       sourcesystem_cd=”sourcesystem_cd24″
       upload_id=”upload_id24″>
           event_id6
           patient_id15            concept_cd3
           observer_cd3
           2006-05-04T18:13:51.0Z
           modifier_cd0
           valuetype_cd0
           tval_char0
           3.141592653589
           valueflag_cd0
           3.141592653589
           units_cd0
           2006-05-04T18:13:51.0Z
           location_cd0
           3.141592653589

Object Explanations #

Patient Data #

Object	Explanation
PatientData	The root element that holds data from the patient data tables. May contain any number of visit_dimension, concept_dimension, provider_dimension, patient_dimension and observation_fact elements. They can occur in any order

Event Set #

Object	Explanation
event_set	Data from the visit_dimension table
event	One row of data from the visit_dimension table.
event_id	A choice between Encounter_Num (if source is HIVE) or Encounter_Id if another source. A source with “_e” at the end is encrypted.
patient_id	A choice between Patient_Num, (if source is HIVE) or Patient_Id if another source. A source with “_e” at the end is encrypted.
start_date	The date-time that the event started.
end_date	The date-time that the event ended.
active_status_cd	A code to represent the meaning of the date fields above.
param	Name value field
event_blob	XML data that includes partially structured and unstructured data about a visit.

Concept Set #

Object	Explanation
concept_set	Data from the concept_dimension table
concept	One row of data from the concept_dimension table.
concept_path	A path that represents the hierarchical specification of the concept
concept_cd	A unique code that represents a concept.
name_char	A string name that represents this concept, idea or person.
concept_blob	XML data that includes partially structured and unstructured data about a concept.

Observer Set #

Object	Explanation
observer_set	Data from the provider_dimension table
observer	One row of data from the provider_dimension table.
observer_path	A path that represents the hierarchical specification of the observer
observer_cd	A unique code that represents a observer.
name_char	A string name that represents this observer, could be person or machine.
observer_blob	XML data that includes partially structured and unstructured data about an observer.

PID Set #

Object	Explanation
pid_set	Data from the patient_mapping table
pid	One set of mappings on a single patient_num
patient_id	A choice between Patient_Num, (if source is HIVE) or Patient_Id if another source. A source with “_e” at the end is encrypted.
patient_map_id	A patient_id that should have the same patient_num as the patient_id in this pid.

EID Set #

Object	Explanation
eid_set	Data from the encounter_mapping table
eid	One set of mappings on a single visit_num
event_id	A choice between visit_num, (if source is HIVE) or Visit_Id if another source. A source with “_e” at the end is encrypted.
event_map_id	A visit_id that should have the same patient_num as the visit_id in this eid.

Observation Set #

Object	Explanation
observation_set	Data from the observation_fact table.
Observation	One row of data from the observation_fact table.
event_id	A choice between encounter_num (if source is HIVE) or encounter_id if an other source. A source with “_e” at the end is encrypted.
patient_id	A choice between patient_num, (if source is HIVE) or patient_id if another source. A source with “_e” at the end is encrypted.
concept_cd	A unique code that represents a concept.
observer_cd	An ID that represents the provider, which could be a physician or a machine such as an MRI machine.
start_date	The date that the observation was made, or that the observation started. If the data is derived or calculated from another observation (like a report) then the start date is the same as the observation it was derived or calculated from.
modifier_cd	hierarchical derivations of a common observation
ValType_Cd	A code representing whether a value is stored in the TVal column, NVal column, or observation_blob column.
TVal_Char	A text value.
NVal_Num	A numerical value.
ValueFlag_Cd	A code that represents the type of value present in the NVal_Num, the TVal_Char or observation_blob column
Quantity_Num	The number of observations represented by this fact.
Units_Cd	A textual description of the units associated with a value.
End_Date	The date that the observation ended. If the data is derived or calculated from another observation (like a report) then the end_date is the same as the observation it was derived or calculated from.
Location_Cd	A code representing the hospital associated with this visit.
Confidence_Num	A code or number representing the confidence in the accuracy of the data.
Observation_Blob	XML data that includes partially structured and unstructured data about an observation.

Patient Set #

Object	Explanation
patient_set	data from the visit_dimension table
patient	One row of data from the visit_dimension table.
patient_id	A choice between patient_num, (if source is HIVE) or patient_id if another source. A source with “_e” at the end is encrypted.
start_date	The date-time that the patient was born.
end_date	The date-time that the patient died.
vital_status_cd	A code to represent the meaning of the date fields above.
param	Name value field
patient_blob	XML data that includes partially structured data about a patient

Admin Fields #

Object	Explanation
Update_Date	The date the data was last updated according to the source system from which the data was obtained. If the source system does not supply this data, it defaults to the download_date.
Download_Date	The date that the data was obtained from the source system. If the data is derived or calculated from other data, then the download_date is the date of the calculation.
Import_Date	The date the data is placed into the table of the data mart.
SourceSystem_Cd	A code representing the source system that provided the data.
Upload_Id	Tracking number assigned to any file uploaded.
Document Version:	1.4.1
I2b2 Software Release:	1.4

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Updated on April 27, 2026

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Patient Data Object (PDO) #

Table of Contents #

Introduction #

The i2b2 Hive #

i2b2 Cell Messaging #

i2b2 XML Schema Definitions #

i2b2.xsd #

i2b2_request.xsd #

i2b2_response.xsd #

Patient Data Object (PDO) #

PDO XML Schema Definitions #

i2b2_PDO.xsd #

i2b2_PDO_fields.xsd #

i2b2_PDO_types.xsd #

Example Object #

Object Explanations #

Patient Data #

Event Set #

Concept Set #

Observer Set #

PID Set #

EID Set #

Observation Set #

Patient Set #

Admin Fields #

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