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Published on: December 19, 2020
Low CRB-65 Scores Effectively Rule out Adverse Clinical Outcomes in COVID-19 Irrespective of Chest Radiographic
Alexander Liu1, Robert Hammond1, Kenneth Chan2
1School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK.
Insights
The CRB-65 score effectively predicts COVID-19 pneumonia outcomes, regardless of chest X-ray findings. A CRB-65 score of 0 can rule out adverse events in patients with normal or abnormal chest X-rays.
Area of Science:
- Pulmonology
- Infectious Diseases
- Critical Care Medicine
Background:
- CRB-65 (Confusion, Respiratory rate, Blood pressure, age ≥ 65) is a prognostic score for COVID-19 pneumonia.
- The impact of normal chest X-rays (CXRs) on CRB-65's prognostic value is not well understood.
- This limits the score's application in patients with varying CXR findings.
Purpose of the Study:
- To evaluate how chest X-ray (CXR) abnormalities influence the prognostic accuracy of the CRB-65 score in COVID-19 patients.
- To determine if adding CXR findings improves CRB-65's predictive capability for adverse outcomes.
Main Methods:
- Retrospective analysis of 589 COVID-19 patients.
- Assessment of CRB-65 performance in subgroups with normal versus abnormal CXRs.
- ROC analysis to compare prognostic accuracy and calculation of Negative Predictive Values (NPVs) for key outcomes.
Main Results:
- CRB-65 demonstrated similar prognostic performance for inpatient mortality in patients with normal (AUC 0.67) versus abnormal (AUC 0.69) CXRs.
- A CRB-65 score of 0 showed high NPVs for ruling out mortality, NIV, and critical illness, irrespective of CXR findings.
- Low CRB-65 scores correlated with better inpatient survival compared to high scores, independent of CXR status (p < 0.05).
Conclusions:
- CRB-65, CXR, and CRP are independent predictors of mortality in COVID-19.
- Incorporating CXR findings (normal vs. abnormal) into the CRB-65 score does not enhance its prognostic accuracy.
- A CRB-65 score of 0 serves as a reliable negative predictor for adverse outcomes in COVID-19 patients, warranting prospective validation.
Abstract:
Background: CRB-65 (Confusion; Respiratory rate ≥ 30/min; Blood pressure ≤ 90/60 mmHg; age ≥ 65 years) is a risk score for prognosticating patients with COVID-19 pneumonia. However, a significant proportion of COVID-19 patients have normal chest X-rays (CXRs). The influence of CXR abnormalities on the prognostic value of CRB-65 is unknown, limiting its wider applicability. Methods: We assessed the influence of CXR abnormalities on the prognostic value of CRB-65 in COVID-19. Results: In 589 study patients (71 years (IQR: 57-83); 57% males), 186 (32%) had normal CXRs. On ROC analysis, CRB-65 performed similarly in patients with normal vs. abnormal CXRs for predicting inpatient mortality (AUC 0.67 ± 0.05 vs. 0.69 ± 0.03). In patients with normal CXRs, a CRB-65 of 0 ruled out mortality, NIV requirement and critical illness (intubation and/or ICU admission) with negative predictive values (NPVs) of 94%, 98% and 99%, respectively. In patients with abnormal CXRs, a CRB-65 of 0 ruled out the same endpoints with NPVs of 91%, 83% and 86%, respectively. Patients with low CRB-65 scores had better inpatient survival than patients with high CRB-65 scores, irrespective of CXR abnormalities (all p < 0.05). Conclusions: CRB-65, CXR and CRP are independent predictors of mortality in COVID-19. Adding CXR findings (dichotomised to either normal or abnormal) to CRB-65 does not improve its prognostic accuracy. A low CRB-65 score of 0 may be a good rule-out test for adverse clinical outcomes in COVID-19 patients with normal or abnormal CXRs, which deserves prospective validation.
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