Severity of illness scores may introduce or perpetuate bias when used to ration or prioritize intensive care. Using an economic framework that accounts for both demand and supply-side pathways, we find direct physiology to be the relevant driver of intensive care utilization. A deeper implication and key take-away is that (i) including treatments and diagnosis in severity scores provides a channel to perpetuate bias in the triage process and (ii) evidence of this bias is drawn from unobserved patient-level factors working from both demand and supply-side directions.