OMOP-FHIR DATA

Overview

This repo holds OMOP JSON data sets that can be used to run the OMOP-to-FHIR pipeline available in the MENDS-on-FHIR repo. Using these data sets obviates the need for access to an instance of an OMOP CDM running on an RDBMS. Each folder represents a different data set. Folder names follow the same naming convention: Source-Method-Rows:

• Source: the original data source. Usually a public domain deidentified data resource. Currently only Synthea data sets have been created.
• Method: currently one of {random, cohort}. Random data sets do not maintain referential integrity but will always have a fixed number of rows per table. Cohort-based data sets maintain referential integrity and will have the fixed number of patients. However cohort-based queries will not have a fixed number of rows in clinical data tables in order to maintain referential integrity within a patient's data.
• Rows: The number of rows in a table. See above for difference between random and cohort queries.

An example is the folder synthea-random-20. This folder has OMOP JSON data that was created using Synthea, using a random query, with each table having exactly 20 rows with no referential integrity between tables. The folder synthea-cohort-10 has OMOP JSON data created using Synthea based on a 10-person cohort with referential integriy.

Usage

The MENDS-on-FHIR repo contains a script that mounts one of the data folders from this repository as a submodule that is used as its input OMOP JSON to start the OMOP-to-FHIR conversion pipeline. See the README description in the MENDS-on-FHIR repo which describes how to alter the appropriate environment variable to mount a different data folder.

The tools folder

The data folders are the end-product of an earlier process that extracts OMOP JSON from an OMOP CDM V5.3 RDBMS. In the tools folder, we provide tooling for creating the OMOP JSON files.

The figure below, a generalized version from our technical publication. It shows a more complete data pipeline that includes generating OMOP CDMs and OMOP JSON files from public domain sources (blue boxes). Our public-facing work to date only uses the Synthea synthetic patient data generation system. Only those parts highlighted in blue are implemented in this folder. The pipeline in green is implemented in the MENDS-on-FHIR repo, which expects OMOP JSON created here to have been generated.

This README is a work in progress. We provide detailed steps in the file 'Commands_Synthea_to_OMOP.md':

1. We followed the instructions on the Synthea repo to generate CSV files with the desired population (using the -p argument. We used the Synthea3.0.0 tagged code rather than HEAD as needed by the OHDSI ETL tool.

2. We followed the instructions on the OHDSI ETL-Synthea R tool to populate a Postgres database.

   • There is an error in the ETL-Synthea code that is fixed in the 'fixes.sql' script. A pull request has been submitted to the OHDSI ETL-Synthea repo.

3. We performed pg_dump to extract the Postgres database with the OMOP terminology and the ETL'd Synthea data.

   NOTE: Steps 1-3 were performed using a bare-metal Postgres RDBMS. The OHDSI ETL-Synthea R tool reads large vocabulary files into memory before inserting into the database. My laptop did not have sufficient memory to perform this step no matter how much memory I allocated to the Docker Desktop application.

4. In this directory, we provide the Dockerfile that consumes pg_dump files created in the previous step to create a Postgres Docker image prepopulated with the OMOP vocabularies and the ETL'd Synthea data.

5. In this directory, we provde a Docker image of the Python-based extract tool that queries the Docker Postgres DB and creates the OMOP JSON files used by the MENDS-on-FHIR pipeline.

6. In this directory, we provide a script/docker compose YML file that launches one of the pre-populated Postgres images and the Python extract image that performs the actual OMOP JSON extraction.