- The risk of developing an acute coronary event (ACE) in patients presenting to the emergency room with chest pain or shortness of breath was assessed in a prospective blinded fashion. The Time Insensitive Predictive Instrument (TIPI), which is appropriate for both prospective and retrospective assessment, was used to determine the risk. The average predictive probability for developing ACE among the 168 patients examined was 36.5%. The triage process created groups of patients with significantly different relative risks for ACE. The average predictive probability among the patients discharged from the emergency room was 23%, among those hospitalized in internal medicine 44%, and among those hospitalized in the coronary care unit (CCU) 62.4%. Among patients presenting with ACE the predictive probability determined using TIPI was 57.6% compared to 26.3% in patients without ACE. This difference was unaffected by the triage process or the decision where to hospitalize. TIPI permits assessment of the emergency room physician's decisions and also mirrors the limitations of the system as a whole in treating patients referred to the emergency room for a suspected acute coronary event.