Prediction of prognosis by markers in community-acquired pneumonia

Abstract

Early identification of patients with community-acquired pneumonia (CAP) at risk of poor outcome is critical for defining site of care and may impact on hospital resource consumption and prognosis. The Pneumonia Severity Index and CURB-65 are clinical rules that accurately identify individuals at risk of death. However, these scores have some limitations. Therefore in recent years, increasing attention has been being paid to research on biomarkers, since they have the potential to resolve fundamental issues regarding prognostic prediction that cannot be readily addressed using CAP-specific scores. Nevertheless, the use of biomarkers in this context needs to be validated in prospective trials so as to elucidate how they can best be applied in practice. This review examines the usefulness of biomarkers, whether used alone or in conjunction with other clinical severity of illness scores, for identifying CAP patients at risk of short- and long-term mortality and for predicting both the need for intensive care unit admission and the potential for treatment failure.

Keywords::

• biomarker
• clinical stability
• community-acquired pneumonia
• intensive care unit
• mortality
• prognosis
• treatment failure

Financial & competing interests disclosure

This work was supported by the Fondo de Investigación Sanitaria de la Seguridad Social (grant 11/01106) and by Spain’s Ministerio de Economia y Competitividad, Instituto de Salud Carlos III – co-financed by the European Regional Development Fund (ERDF) ‘A way to achieve Europe’, Spanish Network for Research in Infectious Diseases (REIPI RD12/0015). Viasus D is the recipient of a research grant from the REIPI. Garcia-Vidal C is the recipient of a Juan de la Cierva research grant from the Instituto de Salud Carlos III, Madrid, Spain. Simonetti A is the recipient of a research grant from the IDIBELL – Bellvitge Biomedical Research Institute. The funding sources had no role in the study design, in the collection, analysis and interpretation of data, or in the writing of the manuscript. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • The majority of biomarkers have been found to be independent predictors of short- and long-term mortality, intensive care unit (ICU) admission and treatment failure in patients with community-acquired pneumonia (CAP).

• • Importantly, studies are inconsistent regarding whether biomarkers are better than CAP-specific scores for predicting prognosis, as evidenced by the results of area under the receiver operating characteristic (AUROC) curves.

• • Adding biomarkers to scores such as Pneumonia Severity Index, CURB-65, APACHE II and SOFA improved their predictive capability, as indicated by a significant increase in the AUROC curves.

• • There is a need not only for existing findings to be validated by large studies but also for further studies evaluating the relationship between biomarkers and the need for ICU admission and treatment failure or clinical stability in CAP.

• • Future research should seek to elucidate how biomarkers can best be used in clinical practice, which ones are the most appropriate and which cut-off levels should be applied for predicting prognosis in CAP.

• • Future studies should evaluate the predictive value of combinations of biomarkers from distinct biological pathways and also examine whether changes in biomarker levels during the course of the disease may help physicians to identify patients at higher risk of deterioration and poor outcomes.