Early Identification of Inpatients at Low Risk for COVID-19 Pneumonia

microscopic pneumonia in lungs
microscopic pneumonia in lungs
Can patients at low-risk for COVID-19 pneumonia be identified upon hospital admission based on patient data and minor criteria developed by IDSA and ATS?

The use of initial biochemical findings and the application of less than 3 Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS) minor criteria can help to identify patients at low risk for SARS-CoV-2 pneumonia. This was among results of a study conducted across several Spanish hospitals that included patients from the first and second COVID-19 waves, published in the journal Chest.

“Early identification of patients with low-risk SARSCoV-2 pneumonia who will not require ICU admission and or progress to death could help with resource allocation during periods of hospital bed shortages,” noted authors of the current study. The researchers therefore assessed a simple method for identifying low risk patients during ED evaluation.

This multicenter cohort study included a derivation cohort with 1274 patients and 2 validation cohorts — 1 with 830 patients who experienced the first wave of COVID-19, and a second wave validation cohort with 754 patients. In the derivation cohort, a multinomial regression analysis was carried out to compare the following groups of patients: (1) those who were admitted to the ward (evaluated as low risk); (2) those who were admitted to the intensive care unit (ICU) directly; (3) those who were transferred to the ICU following general ward admission; and (4) those who died.

Results of the study showed that in the derivation cohort, similarities were observed among those either directly admitted or transferred to the ICU and those who died. Thus, these individuals could be merged into 1 group.

Through regression logistic analysis, researchers identified 5 independently associated variables as being predictors of low risk for pneumonia (ie, not dying and/or requiring ICU admission): (1) peripheral blood oxygen saturation/ fraction of inspired oxygen (SpO2/FiO2) ratio of >450 (odds ratio [OR], 0.233; 95% CI, 0.149-0.364); (2) less than 3 IDSA/ATS minor criteria (OR, 0.231; 95% CI, 0.146-0.365); (3) lymphocyte count of more than 723 cells/mL (OR, 0.539; 95% CI, 0.360-0.806); (4) urea level of less than 40 mg/dL (OR, 0.651; 95% CI, 0.426-0.996); and (5) C reactive protein (CRP) of less than 60 mg/dL (OR, 0.454; 95% CI, 0.285-0.724).

The area under the curve (AUC) in the derivation cohort was 0.802 (95% CI, 0.769-0.835; P <.001), with a sensitivity and specificity of 85.9% and 55.6%, respectively, and positive and negative predictive values of 87.2% and 52.8%, respectively. In the validation cohorts, the AUCs were 0.779 (95% CI, 0.742-0.816) and 0.801 (95% CI, 0.757-0.845) in the first wave and second wave, respectively.

Limitations of the current study included the fact that some variables were missing from the analysis. Further, potential differences in ICU strategies existed among the different hospitals. Additionally, a biochemical analysis was performed at admission only and did not include the use of dynamic modeling.

The researchers concluded that “A combination of parameters — including host response (eg, lymphocyte count and CRP levels); lung function (eg, the SpO2/FiO2 ratio); and <3 IDSA/ATS minor criteria — provides a feasible tool for decision-making processes in the ER as it relates to evaluating disease severity for safe triage and resource allocation [for patients with COVID-19].”


Menéndez R, Méndez R, González-Jiménez P, et al. Early recognition of low-risk SARS-CoV-2 pneumonia: A model validated with initial data and IDSA/ATS minor criteria. Chest. Published online May 21, 2022. doi:10.1016/j.chest.2022.05.013