Objective To investigate the predictive performance of lactate, CURB-65, and a combination of lactate and CURB-65 (LAC-CURB-65) for mortality, hospitalisation and intensive care unit (ICU) admission in pneumonia patients in the emergency department (ED).

Methods Consecutive adult patients with pneumonia presenting from January 2012 to May 2014 were divided into low-, moderate- and high-risk groups according to lactate (<2.0, 2.0–4.0, >4.0 mmol/L), CURB-65 (≤1, 2, ≥3) and LAC-CURB-65 (patients with two low risks, any moderate risk, any high risk) values. Mortality, hospitalisation and ICU admission rates were compared between risk classes.

Results Of 1641 patients, 861 (53%) were hospitalised (38% to a general ward, 15% to the ICU) while the remaining 780 (47%) were treated as outpatients or observed in the ED. 547/1641 (33%) patients died within 28 days. Lactate and CURB-65 were higher in patients who died, were hospitalised or were admitted to the ICU compared with patients who were not (p<0.001). Lactate and CURB-65 independently predicted outcomes. The performance of lactate in predicting 28-day mortality, hospitalisation and ICU admission was higher than that of CURB-65 (p<0.01). For LAC-CURB-65, patients at low or moderate risk had mortality rates of 2% and 14%, respectively, and hospitalisation rates of 15% and 40%, respectively, while none were admitted to ICU. Patients at high risk had the highest mortality (52%), hospitalisation (70%) and ICU admission rates (27%).

Conclusions Lactate is superior to CURB-65 in predicting mortality, hospitalisation and ICU admission in pneumonia patients in the ED. LAC-CURB-65 significantly improved the predictive value of CURB-65.