Baseline C-reactive protein level as a predictor of mortality in bacteraemia patients: a population-based cohort study

Abstract

We examined the association between C-reactive protein (CRP) level at time of blood culture (BC) draw and mortality following bacteraemia. Our population-based cohort study comprised all first-time monomicrobial bacteraemia episodes in adults in a Danish county during 1996-2004 (n = 5267). CRP was measured within 24 h of the first positive BC draw. Cox regression was used to compute mortality rate ratios (MRRs) associated with CRP level quartiles (10-64 (reference), 65-143, 144-240 and 241-688 mg/L), controlling for age, gender, comorbidity, specialty, acquisition of infection, and infection focus. We also looked for a biological interaction between CRP level and high magnitude of bacteraemia (three of three culture bottles positive). Thirty-day mortality increased with higher CRP level: adjusted 0-30-day MRRs for patients in the second, third and fourth CRP quartiles were 1.38 (95% CI 1.13-1.69), 1.70 (95% CI 1.40-2.06), and 2.38 (95% CI 1.96-2.87), respectively (p for trend <10(-4)). In contrast, mortality associations with CRP during 31-365 days of follow-up were weak (adjusted MRRs for the second to fourth quartiles ranged from 1.18 to 1.28). A high magnitude of bacteraemia strengthened the association between high CRP level and 30-day mortality. We conclude that the CRP level, measured concurrently with the first positive BC, independently predicted 30-day mortality in adult bacteraemia patients.