The aim of the present study was to investigate the prognostic value of the initial serum lactate level in patients with community-acquired pneumonia (CAP).

We collected data on hospitalized adult patients with CAP via the study hospital emergency department between October 2012 and September 2013. Demographics, comorbidities, and physiologic and laboratory variables including initial C-reactive protein (CRP) and serum lactate level were extracted from the electronic medical record. The primary outcome was inpatient mortality. Comparisons between survivors and nonsurvivors were performed, and multivariable logistic regression analyses were constructed as dependent variables of both continuous and categorical varieties.

A total of 397 patients were enrolled, and the mortality cases were 46 (11.6%). The mean lactate level was 1.7 ± 1.4 mmol/L and was significantly higher in the nonsurvivor group than in the survivor group (2.4 ± 2.2 mmol/L vs 1.6 ± 1.2 mmol/L). In the multivariable logistic regression model for inpatient mortality constructed using lactate, CRP, and laboratory variables of pneumonia severity index (PSI), lactate and CRP remained as significant factors, but laboratory variables of PSI were not. In other multivariable logistic regression models for the outcome constructed using collected laboratory variables and PSI, lactate remained as a significant factor (adjusted odds ratio, 1.24; 95% confidence interval, 1.01-1.53; P = .042 by continuous variable; adjusted odds ratio of third tertile, 2.60; 95% confidence interval, 1.02-6.66; P = .046 by category variable). C-reactive protein and albumin were also left as significant factors.

The initial serum lactate level is independently associated with mortality in hospitalized patients with CAP. However, laboratory variables of PSI or others were not, except CRP and albumin.