This study sought to validate 25 factors that critical care nurses perceived to be associated with subsequent deterioration following intrahospital transfer from intensive care units (ICUs) to ward inpatient units. Patient complexity was most commonly linked to post-ICU adverse events, while specific system factors were associated with a lower proportion of post-ICU adverse events. These results suggest that multiple system-level interventions would be needed to improve the safety of ICU-to-ward transfers.