C-reactive protein and albumin kinetics before community-acquired bloodstream infections - a Danish population-based cohort study

Abstract

Early changes in biomarker levels probably occur before bloodstream infection (BSI) is diagnosed. However, this issue has not been fully addressed. We aimed at evaluating the kinetics of C-reactive protein (CRP) and plasma albumin (PA) in the 30 days before community-acquired (CA) BSI diagnosis. From a population-based BSI database we identified 658 patients with at least one measurement of CRP or PA from day -30 (D-30) through day -1 (D-1) before the day of CA-BSI (D0) and a measurement of the same biomarker at D0 or D1. Amongst these, 502 had both CRP and PA measurements which fitted these criteria. CRP and PA concentrations began to change inversely some days before CA-BSI diagnosis, CRP increasing by day -3.1 and PA decreasing by day -1.3. From D-30 to D-4, CRP kinetics (expressed as slopes - rate of concentration change per day) was -1.5 mg/l/day. From D-3 to D1, the CRP slope increased to 36.3 mg/l/day. For albumin, the slope between D-30 to D-2 was 0.1 g/l/day and changed to -1.8 g/l/day between D-1 and D1. We showed that biomarker levels begin to change some days before the CA-BSI diagnosis, CRP 3.1 days and PA 1.3 days before.

Keywords: Albumin; C-reactive protein; community acquired bloodstream infections.

Fig. 1.

Daily number of specimens of CRP and PA from day −30 through day 1 (in relation to the day of the CA-BSI).

Fig. 2.

CRP (upper panel) and PA (lower panel) course from day −30 through the day after CA-BSI. The observed mean values (points) are fitted as two linear functions (lines) which are connected at the point of course change (indicated by an arrow).

Fig. 3.

Scatter plots of CRP individual slopes from day −30 (D–30) through day −4 and from day −3 through the day after CA BSI (D1) (226 patients) and PA individual slopes from D–30 through day −2 and from day −1 through D1 (210 patients). Patients with monomicrobial Gram-positive CA-BSI are presented as dots, with monomicrobial Gram-negative CA-BSI as triangles, and with polymicrobial CA-BSI as circles.