Association of a telephone triage service for emergency patients with better outcome: a population-based study in Osaka City, Japan

Telephone triage service in emergency care has been introduced in many countries, and it is important to determine the effect of telephone triage service on the outcome of emergency patients. The aim of this study was to evaluate the effect of telephone triage service on the outcome of emergency patients using propensity score. METHODS DESIGN, SETTINGS, AND PARTICIPANTS: This was a retrospective study with a study period from January 2016 to December 2019. We included all patients transported by ambulances of the Osaka Municipal Fire Department during study period. EXPOSURE: Telephone triage service. OUTCOME MEASURES AND ANALYSIS: The main outcome of this study was unfavorable outcome following use of the telephone triage service. In this study, unfavorable outcome was defined as patients who were admitted, transferred, or died after care in the emergency department. Propensity scores were calculated using a logistic regression model with 12 variables that were present before the telephone triage service was used or were indicative of the patient’s condition. Data analyses were not only propensity score matching but also a multivariable logistic regression model and regression model with propensity score as a covariate. MAIN RESULTS: The number of patients eligible for analyses was 707 474. Of these patients, 8008 (1.0%) used the telephone triage services and 699 466 patients (99.0%) did not use it. The number of patients with an unfavorable outcome was 407 568 (57.6%) in the total cohort. Of them, 2305 patients (28.8%) used the telephone triage service and 297 601 patients (42.5%) did not use it. For propensity score matching, 8008 patients were matched from each group. Use of the telephone triage service was inversely associated with unfavorable outcome in a multivariate logistic regression model with propensity score as a covariate [adjusted odds ratio (OR) 0.874; 95% confidence interval (CI), 0.831–0.919] and propensity score matching (crude OR, 0.875; 95% CI, 0.818–0.936). CONCLUSIONS: This study revealed that the use of the telephone triage service in Osaka city, Japan was associated with better outcomes of patients transported by ambulance.