October 20, 2009 — Japanese researchers have developed a new computer algorithm that uses data from emergency calls to help get emergency response vehicles more quickly to those most at risk of dying.
The algorithm had higher than 80% sensitivity at identifying those with estimated life threat risk greater than 10% at the time of the call. Kenji Ohshige, MD, PhD, and researchers from the Yokohama City University School of Medicine in Japan describe the new algorithm in an article published online October 20 in the open-access journal BMC Emergency Medicine.
The researchers assessed the performance of the new triage system used in more than 60,000 emergency calls during a 6-month period. Emergency call workers entered data into a computer-based triage form during the telephone call. These data included the patient's age, consciousness, breathing status, walking ability, cyanosis, and sweating; whether the patient was lying down; and whether the caller was in a panic. The research objective was to determine whether the algorithm could accurately identify patients with a higher than 10% life threat risk at the time of the call.
The triage data were then compared with the patients' actual condition: death confirmed at the scene by ambulance crews, death in the emergency department, life-threatening condition with cardiac and/or pulmonary arrest, life-threatening condition without cardiac and/or pulmonary arrest, serious but not life-threatening condition, moderate condition, or mild condition.
The researchers found that the algorithm had 80.2% sensitivity, 96% specificity, 42% positive predictive value, and 99.2% negative predictive value for predicting which patients would die or had suffered cardiac and/or pulmonary arrest.
"A patient's life threat risk was quantitatively assessed at the moment of the emergency call with a moderate level of accuracy," Dr. Ohshige and colleagues conclude.
The new system also cut 1 minute from the mean arrival time of the first responder to the scene for highest-risk patients compared with response time for other patients. Effects on survival will be evaluated in future studies.
The authors note that demand for ambulance services in Japan has risen rapidly during the last decade, leading to longer response times. "As delayed response time reduces the number of patients who survive from sudden cardiac arrest, priority dispatch of ambulances to patients in a critical condition has become a matter of importance for the Japanese prehospital emergency medical services system," they write.
The study was supported by the Yokohama Safety Management Bureau, the Japan Society for the Promotion of Science, and the Research Institute of Science and Technology for Society, Japan Science and Technology Agency. The authors have disclosed no relevant financial relationships.
