DESIGN DECISION 01
IDENTITY KEY EXPLORATION
Four ways to identify a patient.
Only one held up.
Research gave us five constraints for the identity key. It had to point
to one person, stay stable over time, be something every patient has,
feel safe to share, and match what partner labs already use.
Each candidate was tested against all five before we committed.
OPTION A
Social Security Number
The US healthcare standard.
Most reliable, most individual.
OPTION B
Phone number
Everyone has one and it is
easy to type at the front desk.
OPTION C
Email and password
Reliable, individual, and
tied to no document.
OPTION D ยท CHOSEN
Email, password, full name
and date of birth
The composite key.
Points to one person
Stable over time
Every patient has one
Safe to share
Recognized by partner labs
Most patients had none
Felt like a link to authorities
One number shared by a family
Patients changed numbers often
Not used by lab systems
Absent from lab databases
No government document
Name and birth date match labs
REJECTED
Excluded the patients we served
REJECTED
Mixed up family members
REJECTED
Could not travel to partner labs
CHOSEN
Unique, portable, no ID required
Each rejection added a requirement. The composite key is what remained when all five held.