Interstitial Lung Fibrosis Following COVID-19 Pneumonia

Abstract

Background and Objectives: Pulmonary fibrosis represents a stage of normal physiologic response to inflammatory aggression, mostly self-limiting and reversible; however, numerous patients treated for SARS-CoV-2 pneumonia present after release from hospital residual lung fibrosis. In this article, we aim to present an optimization method for evaluating pulmonary fibrosis by quantitative analysis, to identify the risk factors/predictors for pulmonary fibrosis in patients with SARS-CoV-2 infection, and to characterize the impact of pulmonary fibrosis on the symptomatology of patients after release from the hospital. Materials and Methods: We performed a prospective observational study on 100 patients with severe forms of pneumonia, with a control group of 61 non-COVID normal patients. Results: We found persistent interstitial changes consistent with fibrotic changes in 69% of patients. The risk of fibrosis was proportional to the values of erythrocyte sedimentation rate (ESR), C reactive protein (CRP), and lactate dehydrogenase (LDH), and to the duration of hospitalization. The imaging parameters correlated with increased risk for interstitial fibrosis were the number of affected pulmonary lobes and the percent of interstitial pulmonary fibrosis. Conclusions: The main risk factors for pulmonary fibrosis post-COVID-19 identified in our study are increased ESR, CRP, LDH, duration of hospitalization and the severity of pneumonia.

Keywords: SARS-COV-2; fibrosis predictors; long COVID; pulmonary fibrosis; quantitative analysis; risk factors.

Figure 1

(a) Bilateral pneumonia with preponderant peripheric topography of inflammatory infiltrates (1); (b) bilateral fibrosis with linear (orange arrows) and “ground glass” pattern (2) and bronchiectasis images (white arrows); (c) bilateral fibrosis with color encoding (green—“ground glass fibrosis and thin reticular fibrosis; orange—linear fibrosis, blue—normal lung densities).

Figure 2

Receiver operating characteristics (ROC) curve for the ability of the “percent of interstitial pulmonary lesions” to predict pulmonary fibrosis. The area under curve (AUC) = 0.827 (0.736–0.918 CI 95%).