Treating the incumbent patient in triage: An analysis of "first come, first served" as a procedural rule

Allocating scarce intensive care resources requires decisions about both which patients should receive priority and which rules should guide those choices. We investigate how the procedural allocation rule "first come, first served" (FCFS) shapes triage decisions. Using experimental ICU bed allocation scenarios, we examine how 8227 scientists across disciplines, surveyed in April and May 2020, make life-and-death allocation decisions when patients differ in clinical and social characteristics and arrive simultaneously or sequentially. Many respondents prioritize the earlier-arriving incumbent patient even when the alternative has stronger survival-relevant claims, indicating a robust arrival-priority pattern. At the same time, the incumbent frame is associated with lower decision avoidance, suggesting that FCFS can function as a morally and organizationally "safe" shortcut in high-stakes settings. Reliance on FCFS varies across expert communities in ways consistent with disciplinary training. Health economists, whose work emphasizes trade-offs and policy evaluation, exhibit lower average adherence to FCFS than other health-related scientists, although substantial reliance on FCFS persists even within this group. The findings highlight a tension between procedural legitimacy and benefit-based triage criteria and suggest that guidelines should anticipate default-preserving tendencies and omission concerns when designing equitable and clinically grounded allocation procedures.