OBJECTIVES: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.