Correlation of Computerized Tomography (CT) Severity Score for COVID-19 pneumonia with Clinical Outcomes

Abstract

IntroductionVarious CT severity scores have already been described in literature since the start of this pandemic. One pertinent issue with all of the previously described severity scores is their relative challenging calculation and variance in inter-observer agreement. The severity score proposed in our study is relatively simpler, easier to calculate and apart from a trained radiologist, can easily be calculated even by physicians with good inter-observer agreement. Therefore, a rapid CT severity score calculation can give a clue to physician about possible clinical outcome without being dependent on radiologist who may not be readily available especially in third world countries.ObjectiveThe objective of this study is to develop a simple CT severity score (CT-SS) with good inter-observer agreement and access its correlation with clinical outcome.MethodsThis retrospective study was conducted by the Department of Radiology and Internal Medicine, at the Aga Khan University Hospital Karachi, from April 2020 to August 2020. Non-probability consecutive sampling was used to include all patients who were positive for COVID-19 on PCR, and underwent CT chest examination at AKUH. Severity of disease was calculated in each lobe on the basis of following proposed CT severity scoring system (CT-SS). For each lobe the percentage of involvement by disease was scored – 0% involvement was scored 0, <50% involvement was scored 1 and >50% involvement was scored 2. Maximum score for one lobe was 2 and hence total maximum overall score for all lobes was 10. Continuous data was represented using mean and standard deviation, and compared using independent sample t-tests. Categorical data was represented using frequencies and percentages, and compared using Chi-squared tests. Inter-observer reliability between radiologist and COVID intensivist for the 10 point CT-SS rated on 0-10 was assessed using the Kappa statistic. A p-value < 0.05 was considered significant for all analyses.ResultsA total of 73 patients were included, the majority male (58.9%) with mean age 55.8 ± 13.93 years. The CT-SS rated on 0-10 showed substantial inter-observer reliability between radiologist and intensivist with a Kappa statistic of 0.78. Patients with CT-SS 8-10 had a significantly higher ICU admission & intubation rate (53.8% vs. 23.5%) and mortality rate (35.9% vs. 11.8%; p = 0.017), as compared to those with CT-SS 0-7.ConclusionWe conclude that the described CT severity score (CT-SS) is a quick, effective and easily reproducible tool for prediction of adverse clinical outcome in patients with COVID 19 pneumonia. The tool shows good inter-observer agreement when calculated by radiologist and physician independently.

Chest CT severity score: assessment of COVID‑19 severity and short-term prognosis in hospitalized Iranian patients

“…According to Hilal et al. [ 28 ], patients with a CT severity score of above 7 had a longer hospital stay, lower intensive care supplements need, and decreased mortality rate. The serum CRP levels and CT features had a significant correlation in patients with a score above 7.…”

Severity of COVID-19 infection in patients with COVID-19 combined with diabetes

“…The area under the curve (AUC) of CTSS prediction of critical COVID-19 was 0.895 with sensitivity of 79.3% and specificity of 88.1% (Fig. 3 ) when the threshold value is 12 [ 12 ].…”

Prediction of prognosis in patients with severe COVID-19 pneumonia using CT score by emergency physicians: a single-center retrospective study

“…COVID-19 is not likely to be severe, but severe cases of pneumonia often lead to death 2 . Because CT is very useful in determining the severity of the disease, various scoring methods using CT have been used, and it has been found that higher scores are related to the severity of the disease 7,8,[11][12][13][14][15][16][17][18] . Three key points influence the scoring by CT.…”

“…The second is how to determine the region of the lung to be scored. Most often, the lungs are read in five lobes (three right and two left lobes) along the anatomical region [7][8][9][11][12][13][14][15][16] . A different way to read the lungs is to divide them into three zones: upper, middle, and lower.…”

“…The radiologist CT score predicted death or ECMO group with ROC of 0.681 (0.518-0.844) with a cutoff value of 19.75, sensitivity of 75%, and specificity of 68%. The death or ECMO versus survival group (median [quartiles]) had a CT score of 21.7 (19.5-22.7) versus 18(15)(16)(17)(18)(19)(20)(21), p = 0.048. The prediction of death or ECMO group by the emergency physicians and radiologists was ROC 0.718 (0.561-0.875) versus 0.681 (0.518-0.844), p = 0.238, with no difference between the two groups.…”