Performance of the Manchester triage system in older emergency department patients: a retrospective cohort study

Background: Studies on the reliability of the MTS and its predictive power for hospitalisation and mortality in the older population have demonstrated mixed results. The objective is to evaluate the performance of the Manchester Triage System (MTS) in older patients (>= 65 years) by assessing the predictive ability of the MTS for emergency department resource utilisation, emergency department length of stay (ED-LOS), hospitalisation, and in-hospital mortality rate. The secondary goal was to evaluate the performance of the MTS in older surgical versus medical patients. Methods: A retrospective cohort study was conducted of all emergency department visits by patients >= 65 years between 01 and 09-2011 and 31-08-2012. Performance of the MTS was assessed by comparing the association of the MTS with emergency department resource utilisation, ED-LOS, hospital admission, and in-hospital mortality in older patients and the reference group (18-64 years), and by estimating the area under the receiver operating characteristics curves. Results: Data on 7108 emergency department visits by older patients and 13,767 emergency department visits by patients aged 18-64 years were included. In both patient groups, a higher emergency department resource utilisation was associated with a higher MTS urgency. The AUC for the MTS and hospitalisation was 0.74 (95% CI 0.73-0.75) in older patients and 0.76 (95% CI 0.76-0.77) in patients aged 18-64 years. Comparison of the predictive ability of the MTS for in-hospital mortality in older patients with patients aged 18-64 years revealed an AUC of 0.71 (95% CI 0.68-0.74) versus 0.79 (95% CI 0.72-0.85). The majority of older patients (54.8%) were evaluated by a medical specialty and 45.2% by a surgical specialty. The predictive ability of the MTS for hospitalisation and in-hospital mortality was higher in older surgical patients than in medical patients (AUC 0.74, 95% CI 0.72-0.76 and 0.74, 95% CI 0.68-0.81 versus 0.69, 95% CI 0.67-0.71 and 0.66, 95% CI 0.62-0.69). Conclusion: The performance of the MTS appeared inferior in older patients than younger patients, illustrated by a worse predictive ability of the MTS for in-hospital mortality in older patients. The MTS demonstrated a better performance in older surgical patients than older medical patients regarding hospitalisation and in-hospital mortality.