RADAR: A Guideline-Grounded Multi-Agent System for the Emergency-Department Sepsis Pathway

At emergency-department triage, sepsis presents like several common non-infectious conditions, and the laboratory values that define organ dysfunction have not yet returned. Existing triage risk scores address recognition alone, leaving the investigation, treatment and disposition decisions that follow unsupported. We present RADAR, a guideline-grounded multi-agent system whose name follows its own order: Recognize assigns a sepsis tier and Assay decides which investigations are indicated, both at triage; a Data gate evaluated in code opens at the first instant the chemistry that defines organ dysfunction has resulted; and Act and Route then decide antimicrobial timing, haemodynamic support and the level of care. Recognize and Route each run on both sides of the gate, so an early call is revised rather than carried forward. Each agent is executed as a decision graph rather than prompted freely: a node exposes one question, a closed answer set and a fixed span of Surviving Sepsis Campaign 2026 text, three validators enforce them, and tiers are assigned by table lookup rather than generated. Over 200 visits at two institutions and 2,733 validated node calls, recognition behind the gate reached sensitivity 0.48 (95% CI 0.28 to 0.68) and specificity 0.94 (0.81 to 0.98) internally and 0.44 (0.23 to 0.67) and 0.91 (0.80 to 0.97) externally, against 0.33 and 0.31 for NEWS ≥ 5 and zero sensitivity for qSOFA ≥ 2. Reassessment changed the tier in 21 of the 56 patients whose chemistry had returned, 18 of them upward, which a score computed once at triage does not represent.