Drug Era

Epic equivalent: No direct equivalent — derived from medication records

The drug_era table represents continuous periods of medication exposure, aggregated from individual drug_exposure records using persistence window gap logic. It answers "how long was the patient on this medication?" rather than "how many prescriptions were written?"

Drug eras work at the RxNorm ingredient level (e.g., "metformin", not a specific brand or formulation).

Field Reference

Field reference (click to expand)

OMOP Field	What It Captures
drug_era_id	Unique identifier
person_id	Links to the patient
drug_concept_id	RxNorm ingredient concept
drug_era_start_date	First day of continuous exposure
drug_era_end_date	Last day + persistence window
drug_exposure_count	Number of source records collapsed
gap_days	Total gap days tolerated within the era

What to Watch For

Common pitfalls

Derived, not raw

Eras are inferred from prescription/administration records. They may not align exactly with actual medication use.

Gap logic is configurable

Typically 30 days between fills. Check your site's ETL configuration.

Ingredient-level only

Eras are at the RxNorm ingredient level, not brand or formulation. Multiple brand-name prescriptions for the same ingredient collapse into one era.

Research Patterns

Question	Tables Involved
Typical duration of statin therapy	drug_era (statin concepts) + era duration
Metformin discontinuation within first year	drug_era (metformin) filtered by duration
Treatment-free intervals in oncology	drug_era (chemo agents) + gaps between eras
Overlapping insulin and GLP-1 agonist use	drug_era with class-level concepts + overlap logic
Fragmented adherence patterns by drug class	gap_days + drug_exposure_count