ImportanceFor critically ill patients with advanced medical illnesses and poor prognoses, overuse of invasive intensive care unit (ICU) treatments may prolong suffering without benefit.ObjectiveTo examine whether use of time-limited trials (TLTs) as the default care-planning approach for critically ill patients with advanced medical illnesses was associated with decreased duration and intensity of nonbeneficial ICU care.Design, setting, and participantsThis prospective quality improvement study was conducted from June 1, 2017, to December 31, 2019, at the medical ICUs of 3 academic public hospitals in California. Patients at risk for nonbeneficial ICU treatments due to advanced medical illnesses were identified using categories from the Soc...