Correlation between Chest CT Severity Scores and Clinical Parameters in Patients with COVID-19 Pneumonia: A Comparative Study between 1st and 2nd Wave

ABSTRACT

Aim and objective: To correlate a chest CT score in COVID-19 pneumonia with clinical severity and inflammatory biomarkers and overall patient's outcome. Materials and methods: In this retrospective single-center analysis, we collected data of 200 patients admitted to Fortis hospital during the peaks of the two waves of the COVID-19 pandemic. Data for 1st wave were collected between July and September 2020 (100 patients) and 2nd wave from March to April 2021 (100 patients). We collected clinical and laboratory data for analysis, derived from the electronic medical record system for the above durations. Only symptomatic patients within 10 days of onset of symptoms who had CT imaging done at admission were included in the study. A team of experienced radiologists analysed the images to determine the CT severity score based on the extent of lobar involvement. Each lung lobe was visually scored from 0-5, 0-no involvement, 1 <5% involvement, 2 5-25% involvement;3 26-50% involvement;4 51-75% involvement;5 >75% involvement. The total CT score was the sum of individual lobar scores ranging from 0 (no involvement) to 25 (maximum involvement). The results of the chest HRCT images were collected and evaluated using the picture archiving and communication systems (PACS). Patient's chest CT score, P/F ratio, O2 requirement, and need for ventilatory support and mortality were compared. Descriptive statistics of patients demographics, clinical, and laboratory results were reported as numbers and relative frequencies. Frequencies of CT scores were calculated and compared with other clinical variables. The Pearson correlation coefficient test was used for correlations, considering p < 0.05 statistically significant. Results: Our study highlights the clinical implication of initial CT findings as a prognostic indicator in patients with COVID-19. In terms of demographic distribution median age was 57.5 and 58 years, respectively, and both the waves had a median male predominance of 65%. Wave 1 had more patients with lower CT scores and higher P/F ratio, whereas wave 2 had a significant lower P/F ratio for the same CT scores as compared to wave 1, especially at higher CT scores. CT score of >18/25 is associated with increased probability of ventilatory requirement and hence increased mortality in both the waves which was found to be statistically significant with p = 0.005. Also, higher CT scores were found to be positively correlated with lymphopenia, increased serum CRP, d-dimer, and ferritin levels. Conclusion: Chest CT imaging has played an important role in monitoring disease progression and predicting prognosis during the COVID-19 pandemic. They can be pivotal in assisting clinicians in diagnosing the severity, predicting the outcomes and most of all, in the management plan for the concerned patient. In our analysis of one of the largest single-centre studies conducted during the two waves of the COVID-19 pandemic in India, CT severity score was directly proportional with inflammatory lab markers, length of hospital stays, and oxygen requirement in patients with COVID-19 infection. CT Chest score of >18/25 on admission is associated with poor prognosis and increased mortality.