EHR integration is the healthcare equivalent of "here be dragons." Every EHR has its own dialect, quirks, and undocumented behaviors.
Integration Methods: Ranked by Pain Level
1. API Integration (Least Pain)
Best EHRs expose FHIR or HL7v2 APIs. Supported, auditable, doesn't require infrastructure access.
2. File Export + Processing (Medium Pain)
You get periodic exports. Process them on your end. Data is 24 hours stale but batch processing is easier to debug.
3. Database Direct Access (Most Pain)
Voids support agreements, requires understanding their database schema, HIPAA nightmares, slow queries kill production.
The Data Chaos Problem
Patient MRN is stored differently in Epic vs Cerner. Different formats, different lengths. Your data model must handle variance. Set up mapping tables.
Practical Integration Patterns
Pattern 1: The Adapter Layer
Build an adapter that translates EHR concepts into your domain model. Handles format conversion, reconciles conflicts, validates constraints, logs transformations.
Pattern 2: Event Sourcing
Record changes as events. Gives you audit trail, ability to replay/rebuild state, change notifications.
Pattern 3: The Reconciliation Loop
Periodically reconcile by pulling full patient list from EHR and comparing with your database. Run daily and alert on discrepancies.