Admission lactate predicts poor prognosis independently of the CRB/CURB-65 scores in community-acquired pneumonia

Community-acquired pneumonia (CAP) is associated with a high risk of respiratory failure or septic organ dysfunction. Lactate is an established early marker of prognosis and sepsis severity, but few data exist in patients with CAP. We performed a retrospective cohort study of consecutive adult CAP patients without treatment restrictions or direct intensive care unit admission. Lactate was measured as a point-of-care test within the capillary admission blood gas analysis, and its prognostic value was compared to the CRB/CURB-65 criteria by multivariate and receiver operating characteristic (ROC) curve analysis. The primary endpoint was the combination of need for mechanical ventilation, vasopressors, intensive care unit admission or hospital mortality. Of 303 included patients, 75 (25%) met the primary endpoint. After ROC analysis, lactate predicted the primary endpoint (area under the curve 0.67) with an optimal cutoff of >1.8 mmol/L. Of the 76 patients with lactate above this threshold, 35 (46%) met the primary endpoint. After multivariate analysis, the predictive value of lactate was independent of the CRB/CURB-65 scores. The addition of lactate >1.8 mmol/L to the CRB/CURB-65 scores resulted in significantly improved area under the curves (0.69 to 0.74, p 0.005 and 0.71 to 0.75, p 0.008 respectively). Fourteen (42%) of 33 and 11 (39%) of 28 patients meeting the endpoint despite presenting with 0 or 1 CRB/CURB-65 criteria had lactate >1.8 mmol/L. Admission lactate levels significantly improved the prognostic value of the CRB/CURB-65 scores in CAP patients. Lactate may therefore be considered a rapid, cheap and broadly available additional criterion for the assessment of risk in patients with CAP.