GEMINI Data Dictionary

About GEMINI Data

GEMINI holds granular hospitalization-level data on 32 hospitals from 20 healthcare organizations across Ontario. GEMINI data include all patients admitted to the department of medicine or intensive care unit and capture >60% of all adult medical and intensive care unit beds in Ontario. GEMINI data are comprised of administrative data (CIHI DAD, NACRS) linked to clinical data extracted from hospital electronic health records. Clinical data include but are not limited to laboratory measurements, radiology, vital signs, blood transfusions, clinical notes, echocardiagram measurements, and medications.

About the GEMINI Data Dictionary

The GEMINI Data Dictionary is an essential resource for anyone doing research at GEMINI. The information in this Data Dictionary is almost entirely based on the metadata belonging to the datasets described. For any questions or comments, please contact GEMINI.data@unityhealth.to.

The following data tables are available at GEMINI for approved research projects. Datacuts of GEMINI data are provided on a project-specific basis. Please refer to Data Availability for hospital or table specific data availability.

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Table name	Source	Description
admdad	ADT, CIHI - DAD	Admission and discharge information for each encounter from the Discharge Abstract Database (DAD) as well as basic encounter demographic information
clinicalnotes	CLINICAL	Detailed clinician and nursing notes for each encounter
derived_variables	GEMINI - DERIVED	Variables derived using GEMINI's in-house functions and the Rgemini package (https://gemini-medicine.github.io/Rgemini/), includes variables such as length of stay, readmission and modified laboratory acute pathology score (mLAPS)
echo	CLINICAL	Echocardiogram tests performed and results
er	CIHI - NACRS	Admission and discharge information for encounters entering through the emergency department from the National Ambulatory Care Reporting System (NACRS)
erconsults	CIHI - NACRS	Details all physician consultations that occurred in the emergency department
erdiagnosis	CIHI - NACRS	Details patient diagnoses from the emergency department using ICD-10-CA codes
erintervention	CIHI - NACRS	Details the intervention(s) using CCI codes that occurred in the emergency department
ipcmg	CIHI - DAD	Provides information regarding the case mix groups which aggregate acute care inpatients with similar clinical and resource-utilization characteristics
ipdiagnosis	CIHI - DAD	Provides information related to the inpatient diagnosis using ICD-10-CA codes

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The following hospitals are included within the GEMINI network. Please refer to Data Availability for hospital and table specific data availability.

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Institution Name	Hospital Name
Grand River Hospital	Grand River Hospital
Halton Healthcare Service	Oakville Trafalgar Memorial Hospital
Hamilton Health Sciences	Hamilton General Hospital
Hamilton Health Sciences	Juravinski Hospital
Humber River Hospital	Humber River Hospital
Kingston Health Sciences Centre	Kingston General Hospital
London Health Science Centre	University Hospital
London Health Science Centre	Victoria Hospital
Mackenzie Health	Richmond Hill
Mackenzie Health	Vaughn Hospital

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The following sources and references can be used as an additional resource for GEMINI data.

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Source Legends	Description	Links
CIHI-DAD	Discharge Abstract Database a database managed by federal agency Canadian Institute Health Information (CIHI) containing hospital inpatient data	https://www.cihi.ca/en/discharge-abstract-database-metadata-dad
CIHI-NACRS	National Ambulatory care reporting system managed by CIHI containing day surgery, outpatient, and emergency department data. Note: GEMINI only collects emergency data.	https://www.cihi.ca/en/national-ambulatory-care-reporting-system-metadata-nacrs
ADT	Admission Discharge Transfer system, part of hospital's information system
CLINICAL	Extracted from data warehouse or source system depending on the hospitals that details all clinical information (lab tests, vitals, medications etc..) about an admission's stay
SNOMED	Systemized Nomenclature of Medicine - Clinical Terms is a systematically organized computer-processable collection of medical terms providing codes, terms, synonyms and definitions used in clinical documentation and reporting	https://www.snomed.org/
CPSO	College of Physicians and Surgeons of Ontario is the regulatory college for medical doctors in Ontario, Canada	https://www.cpso.on.ca/
Stats Canada	Statistics Canada provides neighbourhood-level socioeconomic information in routine census data	https://www.statcan.gc.ca/en/start
GEMINI	Derived variables developed by GEMINI's team of clinical experts and data scientists
LOINC	Logical Observation Identifiers Names and Codes is widely used terminology standard for health measurements, observations, and documents.	https://loinc.org/

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The following table contains variable definitions for all GEMINI data. For more information please contact gemini.data@unityhealth.to

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Data	Variable	Description	Type	Note
admdad	admission_date_time	The date and time that the patient was officially registered as an inpatient for the current hospital admission	text
admdad	admit_category	The initial status of the patient at the time of admission to the reporting facility as coded for CIHI	text	Lookup available in lookup_cihi_codes
admdad	admit_via_ambulance	Identifies whether a patient arrives at the reporting facility via ambulance and the type of ambulance that was used	text	Lookup available in lookup_cihi_codes
admdad	admitting_service_mapped	GEMINI-mapped type of medical service that the patient is admitted to	text	GEMINI mapped
admdad	admitting_service_raw	The type of medical service that the patient is admitted to as per the hospital Admission Discharge Transfer System	text
admdad	age	Patient's age in years at the time of admission	integer
admdad	alc_service_transfer_flag	Indicator for if patient was transferred to ALC service during current hospital admission	text
admdad	blood_transfusion_indicator	Indicates whether or not the patient received a blood transfusion using blood products or components distributed by the reporting facility’s blood bank during the episode of care.	text
admdad	discharge_date_time	The date and time when the patient was formally discharged from their current hospital admission	text
admdad	discharge_disposition	The location where the patient was discharged to or the status of the patient on discharge	integer	Lookup available in lookup_cihi_codes

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The following plot describes the time period of data available at each hospital. Availability is determined by the presence of a genc_id for a given hospital and time period. Click on a hospital to see a detailed breakdown of the specific data tables available for that hospital.

The following plot describes the time period available for each data table. Availability is determined by the presence of a genc_id in the relevant data table for a given time period. Click on the data table of interest for a break down of availability across different hospitals.

The following plot describes which cohort of medicine (and/or ICU) patients are included in GEMINI data.

GIM: Admitted to General Internal Medicine Service only as defined by site
All MED Only: Admitted to any medical service as defined by site
All Med + ICU: Admitted to any medical service or admitted to the ICU during inpatient stay as defined by site

Please consult with an analyst or email gemini.data@unityhealth.to for additional information
Please see data availability plots for site-specific data availability

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Database Version	Database Changes
Version v4.0.0
	Addition of all available CIHI data from all sites up to June 30, 2023
	Addition of all available clinical data from all sites up to June 30, 2023
	Missing v3.0.2 data across multiple tables and sites have been added
	Correction to v3.0.2 data across multiple tables and sites
	Removal of variables across multiple tables. See Variable Definitions or Entity Relationship Diagram to determine which variables are included in each data table
	Removal of lookup_phy_characteristics table. Table available upon request.
Version v3.0.2
	Internal GEMINI Changes
Version v3.0.1
	Internal GEMINI Changes
Version v3.0.0
	Addition of all available CIHI data from all sites up to June 30, 2022
	Addition of all available clinical data from all sites up to June 30, 2022

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Entity Relationship Diagram describes the relationship across all variables within the GEMINI database.