C-reactive protein and other biomarkers—the sense and non-sense of using inflammation biomarkers for the diagnosis of severe bacterial infection

Severe bacterial infection (SBI) poses a significant clinical problem as its mortality and morbidity is still unacceptably high. A systematic literature analysis was performed with an emphasis on recent meta analyses examining the specificity and sensitivity of conventional inflammation biomarkers (C-reactive protein, procalcitonin, interleukin-6, interleukin-8) for diagnosing SBI. Most inflammation biomarkers do not show high sensitivity and are of limited value regarding SBI detection. To the practicing clinician, the sole use of inflammation markers is not useful for differentiating between viral or bacterial origin of infection in an individual patient. Thus, only in combination with clinical biometric markers, taken from patient history and physical examination, is the analysis of inflammation biomarkers to some degree helpful in clinical practice. To date, their sensitivity and specificity have been best captured in the field of neonatology, where levels of interleukin-6 have been measured in combination with relevant perinatal factors. The indiscriminate use of inflammation biomarkers for the diagnosis of SBI may lead to over diagnosis. Novel technologies for pathogen detection and more precise measurement of the host-response using microarrays, allowing for simultaneous detection of multiple genes or proteins, promise to improve the value of laboratory biomarkers for the diagnosis of SBI. Statement of novelty: Presented here is an up-to-date systematic analysis of C-reactive protein and inflammation biomarkers with regard to their use in the diagnosis of SBI. I question whether a broad use of C-reactive protein is useful in patients presenting with infection. The results of the systematic analysis are put into context with recent concerns about over-diagnosing in medicine. This paper is adapted from a publication in the German journal Monatsschrift Kinderheilkunde.