Pulmonary computed tomography symptoms of COVID-19 in vaccinated and non-vaccinated patients

Study design and study population

The study population of this retrospective, single-center cohort study consisted of COVID-19-infected patients admitted to a maximum care hospital. Vaccination status served as the exposure of interest and pulmonary symptoms of her COVID-19 infection by CT graphic served as the outcome variable. Periodic recording of vaccination histories of hospitalized patients at research facilities will begin in July 2021. Consecutive patients who had a chest CT performed during the study time frame from July 1, 2021 to February 14, 2022 were included in the study.

Inclusion criteria were confirmed COVID-19 infection, at least one positive nasal or throat swab RT-PCR test, and at least one chest CT examination during hospitalization. Exclusion criteria were vaccination status, partial vaccination status, ARDS, and lack of data for his patients younger than 18 years.

Declaration of Ethics

This study was approved by the Research Ethics Committee of the Faculty of Medicine, Albert Ludwig University Freiburg (22-1046-Retro). The informed consent requirement was waived by the Ethics Committee of the Faculty of Medicine, Albert Ludwig University Freiburg, due to the retrospective nature of the study (22-1046-Retro). The requirements of the Declaration of Helsinki for human research have been met.

Immunization status

Vaccination status was divided into three categories: unvaccinated, partially vaccinated, and fully vaccinated. Patients who were clearly documented to have not been vaccinated against COVID-19 and had a positive COVID-19 RT-PCR test result were defined as ‘unvaccinated’. A patient who has only one record of her vaccination, or who was diagnosed with her COVID-19 infection within 14 days after receiving her second vaccination, is said to have been partially vaccinated. Classified. Patients with a positive COVID-19 RT-PCR test result/symptoms at least 14 days after the second vaccination were defined as fully vaccinated. Patients who had not been vaccinated or had no documented receipt, and patients with unknown date of last vaccination were categorized as ‘unknown immunization status’ and excluded from the study cohort. Regarding classification, there were no differences between the various vaccines (ChAdOx1 nCoV-19 vaccine – AstraZeneca, BNT162b2 vaccine – Pfizer – BioNTech, mRNA-1273 vaccine – Moderna) with one exception. The patient, who received the Ad26.COV2.S vaccine (Johnson & Johnson-Janssen) as the first vaccine, had a positive COVID-19 RT-PCR test result/at least 14 days before he developed the mRNA vaccine. had to inoculate her twice.

Data collection – demographic and clinical parameters

After identifying the study cohort in the electronic hospital information system and the study site radiology information system, we extracted demographic and clinical data from the electronic patient records.

Immunization status, general information (age and gender), infection parameters (virus subspecies, onset of symptoms), symptoms (dyspnea, cough, fever), pre-existing conditions (BMI, pre-existing conditions), COVID-19 infection Treatment (pharmacological treatment, oxygen nasal cannula, non-invasive ventilation, high-flow oxygen therapy, intubation, intensive care, etc., and any type of oxygen therapy, and complications (pulmonary superinfection, pulmonary embolism, lethal exit, length of hospital stay) were recorded.

CT examination

In research facilities, COVID-19-infected patients underwent CT only on admission for therapeutic outcomes such as suspected pulmonary coinfection or pulmonary embolism, or for unclear clinical constellations. All patients underwent high-resolution CT using a Siemens Somatom Definition Flash (Siemens Healthineers, Erlangen, Germany). For follow-up CT scans, only her first CT scan was evaluated. Acquisition used tube current modulated CARE Dose4D with quality reference mA of 100 mA and automatic tube voltage setting with CARE kV at 120 kV reference with 128 × 0.6 mm collimation. Application of intravenous contrast depended on clinical questions that needed to be answered. A native scan was performed for the extent of infection and suspicion of pulmonary superinfection. Acquired with suspicion of pulmonary embolism. The venous phase was obtained when superinfection with other possible foci of infection was suspected. As the time of CT examination varies in relation to the time of infection, patients were divided into four categories in which CT scans were associated with the onset of symptoms: early stage (CT scans 0–5 days after symptom onset); , advanced stage (CT scan 5–8 days after symptom onset), peak stage (CT scan 9–13 days after symptom onset), and late stage (CT scan ≥14 days after symptom onset)³⁰.

CT analysis

CT images were reviewed at the Picture Archiving and Communication System (PACS). All CT scans were analyzed with an image resolution of 1 mm slice thickness and an axial reconstruction view of the lung window (W: 1500 L: -600). CT images were evaluated by two independent blind readers (PA; certified radiologist with 8 years of experience; EA, radiology trainee with 3 years of experience). PA performed image analysis of the entire study cohort and EA performed image analysis of inter-reader variability). Readers were blinded to clinical data, vaccination status, virus variants, and stages of infection.

Qualitative pattern analysis and scoring

For each CT scan, pneumonia patterns were classified as typical, indeterminate, atypical, and negative for pneumonia based on the RSNA Expert Consensus Statement.^FiveThe CO-RADS and COV-RADS classification systems, which suggest levels of suspicion of COVID-19 pneumonia from very low or category 1 to very high or category 5, were additionally scored.^15,16.

Lung involvement was further qualitatively scored for the degree of lung involvement (unilobar, unilateral multilobar, and bilateral) and the axial and craniocaudal distribution of pneumonia. The predominant pneumonia pattern (GGO, consolidation, mixed or fibrotic) was analyzed. Additional notes were made on the morphology of these features (rounded, subpleural, non-rounded, and not subpleural). A crazy pavement pattern, reticulation, bronchiectasis, bronchial wall thickening, and the presence of nodules were noted. Cavitation, lobar pneumonia, bronchial aerogram, vacuolar signs, organizing pneumonia, reverse halo signs, emphysema, and coronary artery calcification were present.

semi-quantitative scoring

The general degree of pneumonia was scored semi-quantitatively based on the previously described scoring system, with each lobe of the lung scored separately. In summary, the amount of involvement in each leaf was scored as 1 when less than 1/3 of the parenchyma was involved, 2 was given when 1/3 to 2/3 of the leaf volume was involved, and 2 3 was given if exceeded. / One-third of the lobar volume was affected. The maximum possible score for both lungs is 15.^34,35Similarly, the total extent of GGO and integration was recorded.

Inter- and intra-reader variability

Inter- and intra-reader variability was assessed in a random subset of 30 patients. Image analysis was performed at time intervals of at least 3 months to avoid recall bias. Inter- and intra-reader variability was assessed for different scoring systems of pulmonary changes (RSNA score, CO-RAD score, COV-RAD score) and semi-quantitative scoring of pulmonary symptoms on CT graphics. .

statistical analysis

Demographic and clinical parameters according to vaccination status and qualitative and semi-quantitative data of chest CT assessments were presented as arithmetic mean and standard deviation (SD) for continuous variables and counts and percentages for categorical variables. will be Overall, differences in continuous variables were assessed by t-tests and differences in categorical variables by Fisher’s exact test.

Multiple logistic regressions with the resulting CT graphic pulmonary symptoms were computed with stepwise adjustments to determine the association between CT graphic pulmonary symptoms and vaccination status. Model 1 was adjusted for age and pre-existing conditions, model 2 was further adjusted for viral variant, and model 3 was further adjusted for infection stage. Relative risks (RR) with corresponding 95% confidence intervals (CI) were calculated based on the odds ratios and the incidence of outcomes in the non-vaccinated group based on the method of Zhang and Yu.³⁶ (See: vaccinated).

Optionally, use QQ plots to test normality, test homogeneity of variances, correlation coefficients to test homogeneity of variances, and correlation coefficients to test multicollinearity , visually checked the linearity of the independent variables, and checked outliers with strong influence using log-odds and Cook’s distance. Independence was assumed because patients were selected at random. The Wilcoxon rank sum test and the signed rank test were used because the parametric assumptions were not met.

The Krippendorf alpha reliability estimate was used to assess inter- and within-reader variability. A Krippendorf alpha value α ≥ 0.667 indicated acceptable reliability, and a Krippendorf alpha value α ≥ 0.800 indicated high reliability.

All analyzes were performed with R 4.2.0³⁷. P.– Values ​​< 0.05 are considered to indicate statistical significance.