sdc-gdr2omop

Governed Data Records as rows of the OMOP Common Data Model 5.4. A target mapper for sdc-mapper: the core validates the record, resolves every value against its model and reports each one; this package says which OMOP table and column each value goes to, takes each row's concept from the model, and writes one CSV per table. Outbound only. Apache 2.0.

Status: 4.0.1. Models so far, from the FAIR Data Demo: NHANES Participant (xy8upneajsb8vdcmnve01g6g) and NHANES Medication (epbdfmvxc3gbh5f66hhb3o2m).

Use

from sdc_mapper import Engine, load_mapping
from sdc_gdr2omop import OMOPMapper, mapping_path

mapper = OMOPMapper("/path/to/athena")         # or SDC_OMOP_VOCABULARY; without one, every concept_id is 0
result = Engine().map_record(xml, mapper, load_mapping(mapping_path("xy8upneajsb8vdcmnve01g6g")))
result.files            # {"person.csv": ..., "measurement.csv": ..., ...}, the DDL's columns in order
result.report           # every value: lookup, declared, carried or not representable, and why

Through sdc-mapper's CLI and MCP server the mapper is the target omop. Use one mapper for a stream: its row ids are sequences per mapper, so the rows of many records load into one database without colliding. A loader that merges streams assigns final ids.

The target and its terms

OMOP Common Data Model 5.4, from OHDSI's CommonDataModel repository (tag v5.5.0, inst/ddl/5.4/duckdb), licensed Apache License 2.0. This package carries the DuckDB DDL and primary keys unmodified (see NOTICE), and every call loads its rows into an in-memory DuckDB database built from them: a value of the wrong type, a missing NOT NULL column or a duplicate key fails the load and the call.

Vocabularies are never shipped. OMOP's standardized vocabularies come from Athena (https://athena.ohdsi.org), each under its own terms, shown when they are downloaded; some need a license of the user's own. The user gives the directory of their download (CONCEPT.csv, CONCEPT_RELATIONSHIP.csv) at run time. Without one, every concept_id is 0, OMOP's "No matching concept", and the source code stays in the row's source value. The tests use a made-up vocabulary (tests/vocabulary-made-up/), labeled as such, with concept ids no vocabulary uses.

Where values go, and where the concepts come from

A mapping file, one per model (src/sdc_gdr2omop/mappings/), says which table and column each value goes to: +MEASUREMENT/value_as_number (a row of its own), PERSON/gender_concept_id (the record's one PERSON row), RECORD/person_id and RECORD/event_date (what every row of the record takes). Defaults by type keep it short: a quantity is a MEASUREMENT row, an answer or a count an OBSERVATION row.

The concepts come from the model, not the mapping:

• the row's concept is the one the component links to: a LOINC code for each vital sign and laboratory result, a SNOMED CT concept for each condition question;
• an answer's value_as_concept_id is the code its enumerated value is defined by (a LOINC answer, a SNOMED CT or NCI Thesaurus concept);
• a unit is its UCUM symbol;
• a value that is itself a code is looked up in the code system the component names (ICD-10-CM) and followed through "Maps to" to its standard concept.

Each is looked up in the user's vocabulary. A value whose concept comes from the model is a lookup; one the mapping places without a concept from the model is declared; one written only as source text, with no vocabulary OMOP carries, is carried.

What the mapping declares, because NHANES does not say it:

• Dates. NHANES publishes no exam or interview dates. Every row of a 2017-2018 record takes the cycle's first day, 2017-01-01, and each person's observation period is the cycle (2017-01-01 to 2018-12-31).
• Year of birth is 2017 less the age at screening, by a table in the mapping (NHANES top-codes age at 80).
• Gender, race and ethnicity go to OMOP's Gender, Race and Ethnicity vocabularies by tables in the mapping. Two race answers have no code in OMOP's Race vocabulary ("Hispanic, Latino, or Spanish"; "Middle Eastern or North African"): the concept is 0 and the answer is carried as race_source_value.

OMOP's conventions the mapper applies: a NOT NULL concept column with no concept is 0; type concepts are 0, for a site to set in its own profile of the mapping; the component's identifier is the row's source value when the value is not itself a code; a drug exposure with no end date ends the day it starts.

Coverage, measured

python tools/measure.py maps every sample record (200 of each model, a seeded sample of the FAIR Data Demo's NHANES 2017-2018 records) and counts each value's class. Lookups here mean the model names the concept; whether the user's vocabulary holds each code is the vocabulary's.

Every value of every record, the record's provenance and audit included:

The record's data alone (provenance and audit left out):

What OMOP cannot hold here: the record's provenance and audit; the survey's design (weights, strata, primary sampling units, release, interview status), which describes the sample rather than the person; a blood pressure reading's body site and status (MEASUREMENT has no column for either); a second statement of gender (PERSON holds one); a drug's name and a diagnosis code's display text (OMOP keeps the code; the name is the vocabulary's). The NHANES generic drug codes are Multum Lexicon codes, which OMOP's vocabularies do not carry, so each drug exposure's concept is 0 and its code is carried.

Exceptional Values

OMOP has no null flavors and no column that says why a value is missing; concept 0 means "No matching concept", not a reason. So every ISO 21090 code is carried: the code is written as the row's source value for the column the value would have filled (value_source_value for a measurement or an answer, gender_source_value for gender, the code column itself for a value that is a code), beside the row's concept. Where the column has no source value (year_of_birth, a date), the Exceptional Value is lost, and where OMOP requires that column the row cannot be written: every value in it is reported as not representable, with the reason (OMOP requires PERSON.year_of_birth, and the record has no value for it). A mapping file may declare a code lost; it cannot declare one preserved.

The sample records hold no Exceptional Values: the FAIR Data Demo's generators leave NHANES refusals and don't-knows out of the records and count them. The tests put them in.

Tests

pip install -e ".[dev]"
python -m pytest

The suite maps every sample record and loads all of them into one CDM built from the OHDSI DDL, checks lookups against the made-up vocabulary, and exercises Exceptional Values and refused mappings.