Diffusion Capacity Abnormalities for Carbon Monoxide in Patients with COVID-19 At Three-Month Follow-up

Eur Respir J. 2021 Feb 11;2003677. doi: 10.1183/13993003.03677-2020. Online ahead of print.


Objective: To evaluate pulmonary function and clinical symptoms in coronavirus disease 2019 (COVID-19) survivors within 3 months after hospital discharge, and to identify risk factors associated with impaired lung function.

Methods and material: COVID-19 patients were prospectively followed up with pulmonary function tests and clinical characteristics for 3 months following discharge from a hospital in Wuhan, China between January and February 2020.

Results: 647 patients were included. 87 (13%) patients presented with weakness, 63 (10%) with palpitation and 56 (9%) with dyspnea. Prevalences of the three symptoms were markedly higher in severe patients than non-severe patients (19% versus 10% for weakness, p=0.003; 14% versus 7% for palpitation, p=0.007; 12% versus 7% for dyspnea, p=0.014). Results of multivariable regression showed an increased odd in the ongoing symptoms among severe patients (OR: 1.7, 95%CI: 1.1-2.6, p=0.026) or patients with longer hospital stay (OR: 1.03, 95%CI: 1.00-1.05, p=0.041). Pulmonary function test results were available for 81 patients, including 41 non-severe and 40 severe patients. In this subgroup, 44 (54%) patients manifested abnormal diffusion capacity for carbon monoxide (DLCO) (68% severe versus 42% non-severe patients, p=0.019). Chest CT total severity score (TSS)>10.5 (OR: 10.4; 95%CI: 2.5-44.1; p=0.001) on admission and ARDS (OR: 4.6; 95%CI: 1.4-15.5; p=0.014) were significantly associated with impaired DLCO. Pulmonary interstitial damage may be associated with abnormal DLCO.

Conclusion: Pulmonary function, particularly DLCO, declined in COVID-19 survivors. This decrease was associated with TSS of chest CT >10.5 and ARDS occurrence. Pulmonary interstitial damage might contribute to the imparied DLCO.