Diffusion capacity abnormalities for carbon monoxide in patients with COVID-19 at 3-month follow-up

Abstract

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 palpitations and 56 (9%) with dyspnoea. The prevalence of each of the three symptoms were markedly higher in severe patients than nonsevere patients (19% versus 10% for weakness, p=0.003; 14% versus 7% for palpitations, p=0.007; 12% versus 7% for dyspnoea, p=0.014). Results of multivariable regression showed increased odds of ongoing symptoms among severe patients (OR 1.7, 95% CI 1.1-2.6; p=0.026) or patients with longer hospital stays (OR 1.03, 95% CI 1.00-1.05; p=0.041). Pulmonary function test results were available for 81 patients, including 41 nonsevere and 40 severe patients. In this subgroup, 44 (54%) patients manifested abnormal diffusing capacity of the lung for carbon monoxide (D _LCO) (68% severe versus 42% nonsevere patients, p=0.019). Chest computed tomography (CT) total severity score >10.5 (OR 10.4, 95% CI 2.5-44.1; p=0.001) on admission and acute respiratory distress syndrome (ARDS) (OR 4.6, 95% CI 1.4-15.5; p=0.014) were significantly associated with impaired D _LCO. Pulmonary interstitial damage may be associated with abnormal D _LCO.

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

FIGURE 1

Percentage of predicted diffusing capacity of the lung for carbon monoxide (D_LCO) at 3 months after discharge in nonsevere and severe coronavirus disease 2019 patients.

FIGURE 2

Receiver operating characteristic curve analysis of total computed tomography severity score (TSS) on admission for prediction of impaired diffusing capacity of the lung for carbon monoxide during 3-month follow-up. With the cut-off value of 10.5 for the TSS, the area under the curve was 0.765 (95% CI 0.663–0.867; p<0.001) with sensitivity 64% and specificity 84%.

FIGURE 3

Factors associated with impaired diffusing capacity of the lung for carbon monoxide (D_LCO) during 3-month follow-up in multivariable regression analysis. TSS: total severity score; MPA: main pulmonary artery; ARDS: acute respiratory distress syndrome.