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Hazard

DO NOT EDIT BELOW THIS LINE UNLESS YOU KNOW WHAT YOU ARE DOING

Hazard name

Date format locale assumption

General utility label

[2]

Likelihood scoring

TBC

Severity scoring

TBC

Description

Date formatting component uses browser Intl.DateTimeFormat() with default locale, causing date display format to vary based on user's browser settings, creating ambiguity in date interpretation.

Causes

  1. Intl.DateTimeFormat() uses browser default locale without forcing specific format
  2. No forced en-GB or hospital-specific date format
  3. US clinicians see MM/DD/YYYY while UK clinicians see DD/MM/YYYY for same date

Effect

Date interpretation ambiguity where 01/02/2024 could mean February 1st or January 2nd depending on locale.

Hazard

Clinician misreads appointment date, medication start date, or lab result date due to locale format differences.

Hazard type

  • WrongPatientContext

Harm

Missed appointment causing delayed treatment. Medication taken on wrong dates causing under-dosing or over-dosing. Lab results misinterpreted as older/newer than actual causing incorrect clinical decisions.

Existing controls

None identified during initial analysis.

Assignment

Clinical Safety Officer

Labelling

TBC (awaiting scoring)

Project

Clinical Risk Management

Hazard controls

Design controls (manufacturer)

  • Force en-GB locale for all date displays: Intl.DateTimeFormat('en-GB', {day: '2-digit', month: '2-digit', year: 'numeric'}). Displays dates consistently as DD/MM/YYYY format regardless of browser settings. Add date format explanation to UI: "All dates shown as DD/MM/YYYY (day/month/year)."
  • Implement ISO 8601 date display for clarity: display dates as YYYY-MM-DD (ISO format) which is unambiguous across all locales. Example: 2024-02-01 can only mean 1st February 2024. Use in all clinical contexts where date confusion could cause harm.
  • Add month name display for critical dates: instead of 01/02/2024, display "1 Feb 2024" or "01-Feb-2024". Eliminates ambiguity by spelling out month name. Use for medication dates, lab result dates, appointment dates.
  • Implement date format configuration per trust: add hospital_date_format to system configuration. Options: DD/MM/YYYY, MM/DD/YYYY, YYYY-MM-DD. Administrator configures preferred format during deployment. All users see same format (no per-user variation).
  • Add hover tooltip with full date spelling: when hovering over date, display tooltip "1st February 2024" (fully spelled out). Provides confirmation for clinicians uncertain about format. Works for all numerical date displays.

Testing controls (manufacturer)

  • Unit test: Set browser locale to en-US. Render Date component with value="2024-02-01". Assert output is "01/02/2024" (en-GB format forced). Repeat with en-GB, de-DE, fr-FR locales. Assert output always "01/02/2024" regardless of browser locale.
  • Visual test: Screenshot test comparing date displays across different browser locales. Assert all screenshots identical (consistent formatting across locales).
  • Integration test: Create patient with DOB "2000-03-04". Load patient card. Assert DOB displayed as "04/03/2000" (en-GB format) or "4 Mar 2000" (month name format). Parse displayed date. Assert equals 4th March 2000.
  • Accessibility test: Render date with hover tooltip. Simulate hover event. Assert tooltip displays "4th March 2000". Verify screen reader announces full date including month name.
  • Configuration test: Set hospital_date_format="YYYY-MM-DD" in config. Render dates. Assert all dates display as YYYY-MM-DD. Change config to "DD/MM/YYYY". Restart application. Assert dates display as DD/MM/YYYY.

Training controls (deployment)

  • Train clinical staff on date format used in system: explain system displays dates as DD/MM/YYYY (day/month/year) or with month names (1 Feb 2024). Provide examples. Test understanding with quiz questions.
  • Document date format in user manual: first page of user manual states "All dates in this system are displayed as DD/MM/YYYY (day/month/year). For example, 01/02/2024 means 1st February 2024, not 2nd January." Include prominent notice.

Business process controls (deployment)

  • Date format standardization policy: All clinical systems in trust must use same date format. Document preferred format in IT policies. Configure all systems (EHR, lab systems, pharmacy, radiology) with same format.
  • Date verification procedure: For high-risk clinical decisions involving dates (medication start/stop, surgery scheduling, lab result interpretation), clinician must verbally confirm date with second person. Example: "Patient's surgery is scheduled for the first of February, correct?"
  • Incident reporting: Require staff to report cases where date format confusion caused near-miss or adverse event. Analyze reports quarterly. If reports >2/year, consider changing to unambiguous format (ISO 8601 or month names).
  • Patient-facing communication: When dates communicated to patients (appointment letters, medication schedules), spell out month name. Example: "Your appointment is on 1 February 2024" not "01/02/2024". Reduces patient confusion.
  • WrongObservation
  • WrongObservationInterpretation

Residual hazard risk assessment

TBC — awaiting initial controls implementation.

Hazard status

Draft from LLM

Code associated with hazard

  • frontend/src/components/date/Date.tsx