Two Biomarkers Improve CRB-65 Predictability for Death Due to Community-Acquired Pneumonia

Augmenting CRB-65 (confusion, respiratory rate, blood pressure, and age 65 or older) score with troponin T high-sensitive (TnT-hs) and procalcitonin (PCT) help to predict death or intensive care unit (ICU) admission of patients hospitalized with community-acquired pneumonia (CAP), according to the authors of a study published in ERJ Open Research. The study authors added that the validation improved the risk score in additional CAP cohorts, and clinical studies would assess the broad clinical applicability.¹

Pneumonia, CAP, Biomarkers, Pneumococcal | Image Credit: © SOPONE | stock.adobe.com

From a 2010 study, CRB-65 was found to perform well to determine the severity of pneumonia and 30-day mortality in hospital settings. However, for community settings, it over-predicted the probability of 30-day mortality across all predicted risk, so the study authors warned that caution should be used when applying this model. Subsequently, in a 2014 study, investigators aimed to enhance prognostic factors to increase the performance of the model. Their modifications included hypoxemia and specified underlying diseases, which increased the prognosis accuracy and retained independence of laboratory tests, the study authors wrote.^2,3

In the current study, investigators aimed to determine if 8 biomarkers, both individually and in combination with CRB-65, improved the accuracy to predict a patient’s risk for developing severe CAP. The biomarkers included: TnT-hs, PCT, N-terminal pro-brain natriuretic peptide, angiotensin II, copeptin, endothelin-1, lipocalin-2, and mid-regional pro-adrenomedullin (MR-proADM).¹

In the study, investigators included individuals 18 years and older who had pulmonary infiltrate diagnosed by chest imaging between October 2022 to June 2017, as well as one of the following: history of fever, cough, production of purulent sputum, or focal chest signs on auscultation. Patients were excluded if they had an immune deficiency, active tuberculosis, or nosocomial acquisition of infection, according to the authors. The primary end point included study death within 28 days of inclusion or ICU admission during the current infection. The secondary end point was 28-day all-cause mortality.¹

Investigators found that the highest performance in univariate analyses was for TnT-hs with an area under a curve (AUC) of 0.74, followed by PCT at 0.73. For comparison, CRB-65 had an AUC of 0.67, according to the study authors. Further, all biomarkers improved CRB-65 performance except for lipocalin-2 and MR-proADM. Adding CRB-65 to a biomarker consistently enhanced the prediction. For the combination of CRB-65, TnT-hs, and PCT, the AUC was 0.77, which demonstrated the best balance of high predictive value with parsimony, according to the results.¹

The authors reported that the prediction score was consistence across a variety of risk factors, including age, sex, smoking, and heart failure. However, the only exception was chronic obstructive pulmonary disease (COPD), where the scores performed better for patients who did not have COPD. They concluded that using these biomarkers to compliment CRB-65 is feasible and could improve the risk prediction for ICU treatment or death within 28 days.¹

REFERENCES

1. Farhat I, Rosolowski M, Ahrens K, et al. Biomarkers troponin and procalcitonin in addition to CRB-65 enhance risk stratification in patients with community-acquired pneumonia. ERJ Open Res. 2024;10(6):00420-2024. Published 2024 Dec 2. doi:10.1183/23120541.00420-2024

2. McNally M, Curtain J, O'Brien KK, Dimitrov BD, Fahey T. Validity of British Thoracic Society guidance (the CRB-65 rule) for predicting the severity of pneumonia in general practice: systematic review and meta-analysis. Br J Gen Pract. 2010;60(579):e423-e433. doi:10.3399/bjgp10X532422

3. Dwyer R, Hedlund J, Henriques-Normark B, Kalin M. Improvement of CRB-65 as a prognostic tool in adult patients with community-acquired pneumonia. BMJ Open Respir Res. 2014;1(1):e000038. Published 2014 Jul 8. doi:10.1136/bmjresp-2014-000038