A Documented Allergy Sits in the Chart
One past reaction becomes a lifelong safety flag.
- Penicillin: Allergen on file (beta-lactam class)
- Variable: Reaction severity (mild rash to anaphylaxis)
- ~10%: US patients allergy-labeled (report penicillin allergy)
- <10%: Labels confirmed true allergy (on formal testing)
Where the record lives
EHR allergy fields store drug, reaction, and severity.
Why it matters downstream
Every future order gets silently checked against this list.
A single label, many drugs
One allergy can implicate an entire chemical family.
A Related Drug Gets Prescribed
A clinician orders a drug from a chemically adjacent class.
- Cephalexin: New order example (cephalosporin class)
- Beta-lactam: Shared ring system (core reactive structure)
- Every one: Orders needing allergy check (point-of-prescribing screen)
- Common: Missed interaction alerts (without structural AI)
Why the new class was chosen
It treats the infection but shares a chemical backbone.
The naive check fails
Exact drug-name matching misses cross-class chemistry.
Where AI steps in
Structure-aware screening catches what name matching cannot.
Comparing Chemical Scaffolds Atom by Atom
The AI overlays molecular graphs to find shared substructure.
- Graph overlay: Comparison method (ring and side-chain matching)
- Beta-lactam ring: Shared core in penicillins/cephalosporins (primary allergenic trigger)
- ~1–3%: Typical reported cross-reactivity (penicillin to cephalosporin)
- 0–100%: Similarity score range (overlap of shared regions)
Encoding molecules as graphs
Atoms become nodes, bonds become edges for comparison.
Finding shared substructure
Subgraph matching isolates the reactive ring in common.
Scoring the overlap
A similarity percentage summarizes structural closeness.
Turning Similarity Into a Risk Probability
Structural overlap and reaction history combine into one score.
- 2 factors: Model inputs (similarity + severity history)
- Highest: Anaphylaxis history weight (raises risk multiplier)
- 0–100%: Risk output (cross-reactivity probability)
- ~50%: Alert threshold (typical) (triggers clinician warning)
Combining the two signals
Risk scales with structural overlap and past severity.
Why severity history counts
Anaphylaxis history raises caution more than a mild rash.
Calibrating the threshold
A risk cutoff decides when to interrupt the clinician.
The Alert Reaches the Prescriber in Real Time
A risk-scored banner interrupts ordering before the drug is given.
- Order entry: Alert delivery point (before signing the prescription)
- Risk %: Alert content (plus shared structure note)
- Yes: Clinician override allowed (with documented reasoning)
- Prevent reaction: Goal (without blocking needed care)
What the clinician sees
A percentage risk and the shared chemical structure.
Deciding to override or switch
Clinician can pick an unrelated alternative drug class.
Closing the loop
The decision is logged back into the patient record.