About


Here we summarise the baseline characteristics of individuals hospitalised with COVID-19 and individuals previously hospitalised with influenza. A preprint of this research is has been released on medRxiv, with the study protocol available here.


This is a network cohort study that has been developed by the Observational Health Data Sciences and Informatics (OHDSI) collaborative. All analytic code used in the study is available at GitHub. Further collaboration is invited, and the results presented here will be updated as more data becomes available.

Databases


Columbia University Irving Medical Center (CUIMC)

The clinical data warehouse of NewYork-Presbyterian Hospital/Columbia University Irving Medical Center based on its current and previous electronic health record systems.

Daegu Catholic University Medical Center (DCMC)

A teaching hospital in Daegu, South Korea, covered by Federated E-health Big Data for Evidence Renovation Network (FEEDER-NET).

Department of Veterans Affairs (VA) (VA OMOP)

VA OMOP data reflects the national Department of Veterans Affairs health care system, which is the largest integrated provider of medical and mental health services in the United States. Inpatient and outpatient care is provided at 170 VA Medical Centers and 1,063 outpatient sites serving more than 9 million enrolled Veterans each year.

Health Data Compass (HDC-UColorado)

Health Data Compass (HDC) is a multi-institutional data warehouse. HDC contains inpatient and outpatient electronic medical data including patient, encounter, diagnosis, procedures, medications, laboratory results from two electronic medical record systems (UCHealth and Children's Hospital of Colorado), state-level all-payers claims data, and the Colorado death registry. Only UCHealth data was used for this study. Acknowledgement statement: Supported by the Health Data Compass Data Warehouse project (healthdatacompass.org).

Health Insurance Review & Assessment (HIRA)

South Korean national claim data from a single insurance service. It contains the observational medical records (including both inpatient and outpatient)of a patient while they are qualified to get the national medical insurance.

HM Hospitales

HM Hospitales inpatient care database including detailed hospital admission information for COVID-19 patients from March 1st to April 20th 2020. HM Hospitales made their data public as part of the COVID Data Save Lifes project.

The Information System for Research in Primary Care (SIDIAP)

The Information System for Research in Primary Care (SIDIAP; www.sidiap.org) is a primary care records database that covers approximately 80% of the population of Catalonia, North-East Spain. Healthcare is universal and tax-payer funded in the region, and primary care physicians are gatekeepers for all care and responsible for repeat prescriptions.

Premier Healthcare Database

Premier Healthcare Database is a nationally representative all-payer US hospital database that houses data on the inpatient and outpatient visits from non-profit, non-governmental and community and teaching hospitals and health systems. It is a visit-centric, billing database where each visit is linked with a unique billing record.

STAnford medicine Research data Repository (STARR-OMOP)

A clinical data warehouse containing live Epic data from Stanford Health Care, the Stanford Children’s Hospital, the University Healthcare Alliance and Packard Children's Health Alliance clinics.

Tufts-Clinical Academic Research Enterprise Trust (Tufts CLARET)

Electronic medical record data on approximately 1 million patients who recived care beginning in 2006 at Tufts Medical Center (TMC). TMC is an academic medical center that includes Tuft Medical Center's main downtown Boston hospital for adult patients, the Floating Hospital for Children, and associated primary and specialty care clinics. CLARET contains TMC's EHR data fused with data on the same patients from TMC's CoC accredited tumor registry, its oncology EHR, and death data from the Massachusetts State Registry of Vital Statistics. EHR data streams ingested into CLARET include controlled vocabulary data on all domains except cost, and select free text sources and devices.

Cohorts


COVID-19

  • have a hospitalisation (index event) after December 1st 2019
  • with a record of COVID-19 in the 3 weeks prior and up to end of hospitalisation
  • be aged 18 years or greater at time of the index visit
  • have no COVID-19 associated hospitalisation in the six months prior to the index event

Influenza 2014-2019

  • have a hospitalisation (index event) between September 1st 2014 and 1st April 2019
  • with a record of influenza in the 3 weeks prior and up to end of hospitalisation
  • be aged 18 years or greater at time of the index visit
  • have no influenza associated hospitalisation in the six months prior to the index event

Influenza 2009-2010 season

  • have a hospitalisation (index event) between September 1st 2009 and 1st April 2010
  • with a record of influenza in the 3 weeks prior and up to end of hospitalisation
  • be aged 18 years or greater at time of the index visit
  • have no influenza associated hospitalisation in the six months prior to the index event

Each of these cohorts were identified without any requirement for prior observation time, and also with the added restriction of having a minimum of 365 days of prior observation time available. CUIMC used a specific cohort definition for COVID-19, which accounted for local coding practice. SIDIAP included a further COVID=19 cohort where only individuals identified up to the end of March were included (where primary care linkage ended).

Incidence Rate

    

Time Distributions

Time Distributions Table

    
Download Data

Cohort Overlap (Subjects)

Cohort Overlap Statistics