Altitude and Outcomes in Pediatric ARDS: A Multicenter Study

Participants are grouped according to the altitude of the pediatric intensive care unit (PICU) where they are admitted: low altitude (0-1500 m), intermediate altitude (1501-2500 m), high altitude (2501-3500 m), and very high altitude (\>3500 m). Altitude is treated as the primary exposure variable. No therapeutic intervention is administered as part of this study.