Determining extent of COVID-19 pneumonia on CT based on biological variables

Abstract

Covid-19 pneumonia CT extent correlates well with outcome including mortality. However, CT is not widely available in many countries. This study aimed to explore the relationship between Covid-19 pneumonia CT extent and blood tests variations. The objective was to determine for the biological variables correlating with disease severity the cutoff values showing the best performance to predict the parenchymal extent of the pneumonia. Methods: Bivariate correlations were calculated between biological variables and grade of disease extent on CT. Receiving Operating Characteristic curve analysis determined the best cutoffs for the strongest correlated biological variables. The performance of these variables to predict mild (<10%) or severe pneumonia (>50% of parenchyma involved) was evaluated. Results: Correlations between biological variables and disease extent was evaluated in 168 patients included in this study. LDH, lymphocyte count and CRP showed the strongest correlations (with 0.67, − 0.41 and 0.52 correlation coefficient, respectively). Patients were split into a training and a validation cohort according to their centers. If one variable was above/below the following cutoffs , LDH>380, CRP>80 or lymphocyte count <0.8G/L, severe pneumonia extent on CT was detected with 100% sensitivity. Values above/below all three thresholds were denoted in 73% of patients with severe pneumonia extent. The combination of LDH<220 and CRP<22 was associated with mild pneumonia extent (<10%) with specificity of 100%. Discussion: LDH showed the strongest correlation with the extent of Covid-19 pneumonia on CT. Combined with CRP±lymphocyte count, it helps predicting parenchymal extent of the pneumonia when CT scan is not available.

Association of Inflammatory Markers and CT Scoring as Severity Predictors in COVID-19 Patients

“…This is in par with study done by Gupta P. et.al, [16] with average age of 54.1 years and 52 years in patient having severe and non-severe lung involvement respectively. Our study showed male predominance (Male 65%) which is similar to study by Tordjman M. et al, [9] which had a male predominance of 64.8% and study by Gupta P. et.al, [16] in his study in Indian population, found male predominance of 66.5%.…”

“…These results are also in correlation with studies published by, Tordjman M et.al. [9] Zhang J. et al [18] Orlacchio A et al [26] All these studies were supportive of significant positive correlation of CRP with CT severity score. Tordjman M. et al [9] also suggested that along with LDH, CRP can be used to predict parenchymal extent of the pneumonia.…”

“…LDH is an inflammatory marker and has been shown to be increased during acute and severe lung damage. [8] Strongest correlation between CRP, LDH and severity of SARS CoV-2 infection has been reported in many other studies also [9][10][11].…”

“…Many previous studies had demonstrated the significant strong linear regression of CRP and LDH with regard to the severity of pulmonary lesions on CT scan in COVID-19 patients [6,7,[9][10][11][12][13]. Therefore, current study aimed to analyze the relationship between inflammatory blood variables with extent of CT lesions in COVID-19 pneumonia and to find the best cut-off values for blood parameters correlating with extent of lesions in chest CT to explore most useful prognostic factor for early, accurate and individualized assessment of COVID-19 patients.…”

Comparison of Clinical Features and CT Temporal Changes Between Familial Clusters and Non-familial Patients With COVID-19 Pneumonia

“…showed that there was a significant negative correlation between the degree of pulmonary inflammation on chest CT and the lymphocyte count (34). Another previous study from Tordjman et al reported moderate correlations between the severity of CT findings and the lymphocyte count in COVID-19 (35). In our study, more patients in the FC group had a decreased lymphocyte count level, leading to worse CT findings.…”