Bacteremia prediction model using a common clinical test in patients with community-acquired pneumonia

The aim of this study was to construct a bacteremia prediction model using commonly available clinical variables in hospitalized patients with community-acquired pneumonia (CAP).

A prospective database including patients who were diagnosed with CAP in the emergency department was analyzed. Independent risk factors were investigated by using multivariable analysis in 60% of the cohort. We assigned a weighted value to predictive factor and made a prediction rule. This model was validated both internally and externally with the remaining 40% of the cohort and a cohort from an independent hospital. The low-risk group for bacteremia was defined as patients who have a risk of bacteremia less than 3%.

A total of 2422 patients were included in this study. The overall rate of bacteremia was 5.7% in the cohort. The significant factors for predicting bacteremia were the following 7 variables: systolic blood pressure less than 90 mm Hg, heart rate greater than 125 beats per minute, body temperature less than 35 °C or greater than 40 °C, white blood cell less than 4000 or 12,000 cells per microliter, platelets less than 130,000 cells per microliter, albumin less than 3.3 g/dL, and C-reactive protein greater than 17 mg/dL. After using our prediction rule for the validation cohorts, 78.7% and 74.8% of the internal and external validation cohorts were classified as low-risk bacteremia groups. The areas under the receiver operating characteristic curves were 0.75 and 0.79 for the internal and external validation cohorts.

This model could provide guidelines for whether to perform blood cultures for hospitalized CAP patients with the goal of reducing the number of blood cultures.