healthcare-emr-patterns

Healthcare EMR & CDSS Development Patterns

Patterns for building Electronic Medical Record (EMR) and Clinical Decision Support Systems (CDSS). Prioritizes patient safety, clinical accuracy, practitioner efficiency, and clinical audit trail compliance.

When to Use

• Building patient encounter workflows (complaint, exam, diagnosis, prescription).
• Implementing clinical note-taking and structured template chips.
• Designing prescription/medication modules with drug interaction checking.
• Integrating Clinical Decision Support Systems (CDSS) dose validation and warning alerts.
• Implementing clinical scoring tables (NEWS2, qSOFA).
• Designing healthcare-accessible (WCAG AA) UIs for medical data entry.

How It Works

Patient Safety & Pure CDSS Functions

The CDSS engine is a pure function library with zero side effects: input clinical data, output alert arrays. This makes it highly testable.

EMR UI
  ↓ (user enters data)
CDSS Engine (pure functions, no side effects)
  ├── Drug Interaction Checker
  ├── Dose Validator
  ├── Clinical Scoring (NEWS2, qSOFA, etc.)
  └── Alert Classifier
  ↓ (returns alerts)

1. Drug Interaction Checking

Checks a new drug against current medications and known allergies:

interface DrugInteractionPair {
  drugA: string;           // generic name
  drugB: string;           // generic name
  severity: 'critical' | 'major' | 'minor';
  mechanism: string;
  clinicalEffect: string;
  recommendation: string;
}

function checkInteractions(
  newDrug: string,
  currentMedications: string[],
  allergyList: string[]
): InteractionAlert[] {
  if (!newDrug) return [];
  const alerts: InteractionAlert[] = [];
  for (const current of currentMedications) {
    const interaction = findInteraction(newDrug, current);
    if (interaction) {
      alerts.push({
        severity: interaction.severity,
        pair: [newDrug, current],
        message: interaction.clinicalEffect,
        recommendation: interaction.recommendation
      });
    }
  }
  for (const allergy of allergyList) {
    if (isCrossReactive(newDrug, allergy)) {
      alerts.push({
        severity: 'critical',
        pair: [newDrug, allergy],
        message: `Cross-reactivity with documented allergy: ${allergy}`,
        recommendation: 'Do not prescribe without allergy consultation'
      });
    }
  }
  return alerts.sort((a, b) => severityOrder(a.severity) - severityOrder(b.severity));
}