Dynamic changes of pulmonary diffusion capacity in survivors of non-critical COVID-19 during the first six months

Abstract

Background The dynamic trends of pulmonary function in coronavirus disease 2019 (COVID-19) survivors since discharge have been rarely described. We aimed to describe the changes of lung function and identify risk factors for impaired diffusion capacity.Methods Non-critical COVID-19 patients admitted to the Guangzhou Eighth People's Hospital, China, were enrolled from March to June 2020. Subjects were prospectively followed up with pulmonary function tests at discharge, three and six months after discharge.Findings Eighty-six patients completed diffusion capacity tests at three timepoints. The mean diffusion capacity for carbon monoxide (D LCO )% pred was 79.8% at discharge and significantly improved to 84.9% at Month-3. The transfer coefficient of the lung for carbon monoxide (K CO )% pred significantly increased from 91.7% at discharge to 95.7% at Month-3. Both of them showed no further improvement at Month-6. The change rates of D LCO % pred and K CO % pred were significantly higher in 0−3 months than in 3−6 months. The alveolar ventilation (V A ) improved continuously during the follow-ups. At Month-6, impaired D LCO % pred was associated with being female ; p = 0.004) and peak total lesion score (TLS) of chest CT > 8.5 ]; p = 0.007). D LCO % pred and K CO % pred were worse in females at discharge. And in patients with impaired diffusion capacity, females' D LCO % pred recovered slower than males.Interpretation The first three months is the critical recovery period for diffusion capacity. The impaired diffusion capacity was more severe and recovered slower in females than in males. Early pulmonary rehabilitation and individualized interventions for recovery are worthy of further investigations.

Risk factors for impaired pulmonary diffusion function in convalescent COVID-19 patients: A systematic review and meta-analysis

“…In most studies, the diagnostic criterion for the impairment of DLCO was DLCO < 80% of predicted. 17 , 25 , 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 Except for the study performed by Ayad Mohammed Salem, 41 the diagnostic criterion was DLCO < 75% of predicted. There were 100% follow-up rates in 14 studies, 17 , 26 , 27 , 28 , 29 , 30 , 33 , 34 , 35 , 36 , 37 , 38 , 40 , 41 90% in two studies 31 , 32 , 51% in one study 25 and 87.3% in one study 39 Seventeen studies 17 , 25 , 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 have reported 14.3% to 67% COVID-19 survivors with impaired diffusing capacity for carbon monoxide.…”

“…All of the 18 included studies are observational studies, of which 16 are cohort studies, 17 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 one is a prospective, cross-sectional study 40 and one is a cross-sectional case-control study. 41 The included studies were published between 2020 and 2021 and were conducted in seven countries including China, Germany, Italy, Spain, Chile, Norway and Saudi Arabia.…”

“…17 papers 17 , 25 , 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 reported risk factors associated with DLCO impairment and 12 studies were included in the meta-analysis. 17 , 25 , 26 , 28 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 One mentioned risk factor for diffusion capacity for nitric oxide (DLNO) impairment. 27 Due to insufficient data and uncertain definitions of DLNO and Restrictive Pattern, this review focuses on a meta-analysis of risk factors for impaired DLCO.…”

“…All selected studies were assessed for methodological quality with NOS. The NOS score of 12 studies included in the meta-analysis was 7.6 (IQR: 7.0–9.0), indicating that all included studies were of high (50%) 17 , 25 , 26 , 28 , 34 , 41 or moderate (50%) 35 , 36 , 37 , 38 , 39 , 40 quality literature. The quality of evidence (GRADE) in the analyzed studies was “low” or “very low”.…”

“…A total of seven studies 25 , 26 , 35 , 36 , 37 , 39 , 41 have shown that being female is associated with a higher risk for impaired DLCO. Female recovered patients showed a 4-fold greater risk of impaired DLCO than male recovered patients (OR: 4.011; 95% CI: 2.928–5.495).…”