J Korean Med Sci.  2023 Feb;38(8):e55. 10.3346/jkms.2023.38.e55.

The Risk Factors and Outcomes for Radiological Abnormalities in Early Convalescence of COVID-19 Patients Caused by the SARS-CoV-2 Omicron Variant: A Retrospective, Multicenter Follow-up Study

• Wang H
• Yang Q
• Li F
• Wang H
• Yu J
• Ge X
• Gao G
• Xia S
• Xing Z
• Shen W

• KMID: 2539628
• DOI: http://doi.org/10.3346/jkms.2023.38.e55

Abstract

Background
The emergence of the severe acute respiratory syndrome coronavirus 2 omicron variant has been triggering the new wave of coronavirus disease 2019 (COVID-19) globally. However, the risk factors and outcomes for radiological abnormalities in the early convalescent stage (1 month after diagnosis) of omicron infected patients are still unknown.
Methods
Patients were retrospectively enrolled if they were admitted to the hospital due to COVID-19. The chest computed tomography (CT) images and clinical data obtained at baseline (at the time of the first CT image that showed abnormalities after diagnosis) and 1 month after diagnosis were longitudinally analyzed. Uni-/multi-variable logistic regression tests were performed to explore independent risk factors for radiological abnormalities at baseline and residual pulmonary abnormalities after 1 month.
Results
We assessed 316 COVID-19 patients, including 47% with radiological abnormalities at baseline and 23% with residual pulmonary abnormalities at 1-month follow-up. In a multivariate regression analysis, age ≥ 50 years, body mass index ≥ 23.87, days after vaccination ≥ 81 days, lymphocyte count ≤ 1.21 × 10 ^-9 /L, interleukin-6 (IL-6) ≥ 10.05 pg/mL and IgG ≤ 14.140 S/CO were independent risk factors for CT abnormalities at baseline. The age ≥ 47 years, presence of interlobular septal thickening and IL-6 ≥ 5.85 pg/mL were the independent risk factors for residual pulmonary abnormalities at 1-month follow-up. For residual abnormalities group, the patients with less consolidations and more parenchymal bands at baseline could progress on CT score after 1 month. There were no significant changes in the number of involved lung lobes and total CT score during the early convalescent stage.
Conclusion
The higher IL-6 level was a common independent risk factor for CT abnormalities at baseline and residual pulmonary abnormalities at 1-month follow-up. There were no obvious radiographic changes during the early convalescent stage in patients with residual pulmonary abnormalities.

Keyword

COVID-19; Convalescence; CT Abnormalities; Follow-up; Omicron

Figure

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  Fig. 1 Flowchart showing COVID-19 patients included in the study.COVID-19 = coronavirus disease 2019, CT = computed tomography.

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  Fig. 2 The pattern of CT abnormalities observed in this study. (A) CT scan showing subpleural ground-glass opacity (red arrow). (B) CT scan showing subpleural consolidation (red arrow). (C) CT scan showing subpleural interlobular septal thickening (red arrow). (D) CT scan showing subpleural line (red arrow).CT = computed tomography.

• 

  Fig. 3 The correlation heat map showed the correlations between age, BMI, DAV, LHS, WBC, NEUT, LY, PLT, CRP, IL-6, IgM, and IgG for the patient with CT abnormalities (A) and the patient with RA (B). Correlations were computed by Spearman rank correlation. The color in each tile was coded by the strength of Spearman correlation coefficients, and intensity is proportional to the degree of correlation.BMI = body mass index, DAV = days after vaccination, LHS = length of hospital stay, WBC = white blood cell, NEUT = neutrophil, LY = lymphocyte, PLT = platelet, CRP = C-reactive protein, IL-6 = interleukin-6, RA = residual abnormalities.*P value < 0.05.

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  Fig. 4 Graphs show the changes in CT abnormalities over time. (A) The bar graph shows main patterns of lung abnormalities on CT at baseline and 1-month follow-up for different groups. (B) The stacked bar graphs show the distribution of the percentage of involved lung lobes. Paired Wilcoxon signed-rank test comparing changes in CT scores (C) and the number of involved lung lobes (D) between baseline and 1-month follow-up.CT = computed tomography, CR = complete resolution, RA = residual abnormalities, GGO = ground-glass opacity.*P value < 0.05, **P value < 0.01, ***P value < 0.001.

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  Fig. 5 Risk factors associated with CT abnormalities at baseline (A), and RA at 1-month follow-up. OR and corresponding 95% CI were obtained from multivariable logistic regression analysis (Enter method).OR = odds ratio, CI = confidence interval, BMI = body mass index, DAV = days after vaccination, LY = lymphocyte, IL-6 = interleukin-6, CT = computed tomography, CR = complete resolution, RA = residual abnormalities.

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  Fig. 6 The omicron infected patient whose IL-6 was 3.6 pg/mL at baseline. (A) Chest CT obtained at baseline showed bilateral subpleural GGOs. (B) Chest CT obtained at 1-week follow-up showed increased extent of bilateral subpleural consolidations with interlobular septal thickening or reticular lesion. (C) Chest CT obtained 1-month follow-up showed residual consolidations with parenchymal bands. The omicron infected patient whose IL-6 was 2.0 pg/mL at baseline. (D) Chest CT obtained at baseline showed slight subpleural GGOs in the right low lobe. (E) Chest CT obtained at 1-week follow-up showed increased extent of subpleural consolidations in the right low lobe. (C) Chest CT obtained 1-month follow-up showed complete resolution of the lesion in the right low lobe.CT = computed tomography, GGO = ground-glass opacity.

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