Fibrotic-like abnormalities notably prevalent one year after hospitalization with COVID-19

Abstract

Background: We investigated whether COVID-19 leads to persistent impaired pulmonary function, fibrotic-like abnormalities or psychological symptoms 12 months after discharge and whether severely ill patients (ICU admission) recover differently than moderately ill patients.

Methods: This single-centre cohort study followed adult COVID-19 survivors for a period of one year after discharge. Patients underwent pulmonary function tests 6 weeks, 3 months and 12 months after discharge and were psychologically evaluated at 6 weeks and 12 months. Computed tomography (CT) was performed after 3 months and 12 months.

Results: 66 patients were analysed, their median age was 60.5 (IQR: 54-69) years, 46 (70%) patients were male. 38 (58%) patients had moderate disease and 28 (42%) patients had severe disease. Most patients had spirometric values within normal range after 12 months of follow-up. 12 (23%) patients still had an impaired lung diffusion after 12 months. Impaired pulmonary diffusion capacity was associated with residual CT abnormalities (OR 5.1,CI-95: 1.2-22.2), shortness of breath (OR 7.0, CI-95: 1.6-29.7) and with functional limitations (OR 5.8, CI-95: 1.4-23.8). Ground-glass opacities resolved in most patients during follow-up. Resorption of reticulation, bronchiectasis and curvilinear bands was rare and independent of disease severity. 81% of severely ill patients and 37% of moderately ill patients showed residual abnormalities after 12 months (OR 8.1, CI-95: 2.5-26.4). A minority of patients had symptoms of post-traumatic stress disorder, anxiety, depression and cognitive failure during follow-up.

Conclusion: Some patients still had impaired lung diffusion 12 months after discharge and fibrotic-like residual abnormalities were notably prevalent, especially in severely ill patients.

Keywords: COVID-19; Chest imaging; Pulmonary fibrosis; Pulmonary function; Respiratory infection.

Fig. 1

Flowchart of this study.

Fig. 2

Change in pulmonary function during follow-up in COVID-19 patients with moderate or severe disease. Mean FVC, FEV1 and DLCOc (white dots) of COVID-19 patients with moderate and severe disease at 6 weeks, 12 weeks and 52 weeks are illustrated with violin plots and box plots. Individual values are shown with connected lines. A mixed model for repeated measures demonstrates that FVC only improved in severely ill patients between 6 and 12 weeks (p = 0.009). There was no change in FEV1 in both groups during follow-up. DLCOc improved between 6 and 12 weeks and continued to improve afterwards in both groups. Severely ill patients had lower spirometric values during follow-up compared to moderately ill patients (all p<0.001). There was no interaction between disease severity and time (FVC: p_interaction=0.160, FEV1: p_interaction =0.061, DLCOc: p_interaction =0.273).

Fig. 2

Change in pulmonary function during follow-up in COVID-19 patients with moderate or severe disease. Mean FVC, FEV1 and DLCOc (white dots) of COVID-19 patients with moderate and severe disease at 6 weeks, 12 weeks and 52 weeks are illustrated with violin plots and box plots. Individual values are shown with connected lines. A mixed model for repeated measures demonstrates that FVC only improved in severely ill patients between 6 and 12 weeks (p = 0.009). There was no change in FEV1 in both groups during follow-up. DLCOc improved between 6 and 12 weeks and continued to improve afterwards in both groups. Severely ill patients had lower spirometric values during follow-up compared to moderately ill patients (all p<0.001). There was no interaction between disease severity and time (FVC: p_interaction=0.160, FEV1: p_interaction =0.061, DLCOc: p_interaction =0.273).

Fig. 3

Temporal evolution of typical radiological abnormalities in COVID-19 patients with moderate or severe disease. Axial CT-images illustrating the typical evolution of radiological abnormalities over time in a severely ill (A, B, C) and moderately ill (D, E, F) COVID-19 patient at baseline, 3 months and 12 months (left to right). During the acute phase of SARS-CoV-2-infection both patients predominantly demonstrate parenchymal consolidation in a pattern most resembling organizing pneumonia (pronounced peripheral involvement, bronchocentric distribution, perilobular pattern) (A, D). In time, parenchymal abnormalities also resolve in a manner similar to that of organizing pneumonia. At 3 months follow-up, resolution of prior consolidations leaves residual GGO, peripheral curvilinear bands and architectural distortion (B, E). At 12 months follow-up, these residual abnormalities have failed to fully resolve (C, F).