Antibodies Can Last for More Than 1 Year After SARS-CoV-2 Infection: A Follow-Up Study From Survivors of COVID-19

Background: COVID-19 is a global pandemic. The prevention of SARS-CoV-2 infection and the rehabilitation of survivors are currently the most urgent tasks. However, after patients with COVID-19 are discharged from the hospital, how long the antibodies persist, whether the lung lesions can be completely absorbed, and whether cardiopulmonary abnormalities exist remain unclear.Methods: A total of 56 COVID-19 survivors were followed up for 12 months, with examinations including serum virus-specific antibodies, chest CT, and cardiopulmonary exercise testing.Results: The IgG titer of the COVID-19 survivors decreased gradually, especially in the first 6 months after discharge. At 6 and 12 months after discharge, the IgG titer decreased by 68.9 and 86.0%, respectively. The IgG titer in patients with severe disease was higher than that in patients with non-severe disease at each time point, but the difference did not reach statistical significance. Among the patients, 11.8% were IgG negative up to 12 months after discharge. Chest CT scans showed that at 3 and 10 months after discharge, the lung opacity had decreased by 91.9 and 95.5%, respectively, as compared with that at admission. 10 months after discharge, 12.5% of the patients had an opacity percentage >1%, and 18.8% of patients had pulmonary fibrosis (38.5% in the severe group and 5.3% in the non-severe group, P < 0.001). Cardiopulmonary exercise testing showed that 22.9% of patients had FEV1/FVC%Pred <92%, 17.1% of patients had FEV1%Pred <80%, 20.0% of patients had a VO2 AT <14 mlO2/kg/min, and 22.9% of patients had a VE/VCO2 slope >30%.Conclusions: IgG antibodies in most patients with COVID-19 can last for at least 12 months after discharge. The IgG titers decreased significantly in the first 6 months and remained stable in the following 6 months. The lung lesions of most patients with COVID-19 can be absorbed without sequelae, and a few patients in severe condition are more likely to develop pulmonary fibrosis. Approximately one-fifth of the patients had cardiopulmonary dysfunction 6 months after discharge.

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Cardiopulmonary Exercise Testing in Combined Pulmonary Fibrosis and Emphysema

Respiration ◽

10.1159/000513848 ◽

2021 ◽

pp. 369-377

Author(s):

Michael Westhoff ◽

Patric Litterst ◽

Ralf Ewert

Keyword(s):

Body Weight ◽

Pulmonary Fibrosis ◽

Sensitivity And Specificity ◽

Exercise Testing ◽

Cardiopulmonary Exercise Testing ◽

Arterial Oxygen ◽

Peak Exercise ◽

Cutoff Value ◽

Cardiopulmonary Exercise ◽

Peak Vo2

Background: Combined pulmonary fibrosis and emphysema (CPFE) is a distinct entity among fibrosing lung diseases with a high risk for lung cancer and pulmonary hypertension (PH). Notably, concomitant PH was identified as a negative prognostic indicator that could help with early diagnosis to provide important information regarding prognosis. Objectives: The current study aimed to determine whether cardiopulmonary exercise testing (CPET) can be helpful in differentiating patients having CPFE with and without PH. Methods: Patients diagnosed with CPFE in 2 German cities (Hemer and Greifswald) over a period of 10 years were included herein. CPET parameters, such as peak oxygen uptake (peak VO2), functional dead space ventilation (VDf/VT), alveolar-arterial oxygen difference (AaDO2), arterial-end-tidal CO2 difference [P(a-ET)CO2] at peak exercise, and the minute ventilation-carbon dioxide production relationship (VE/VCO2 slope), were compared between patients with and without PH. Results: A total of 41 patients with CPET (22 with PH, 19 without PH) were analyzed. Right heart catheterization was performed in 15 of 41 patients without clinically relevant complications. Significant differences in peak VO2 (861 ± 190 vs. 1,397 ± 439 mL), VO2/kg body weight/min (10.8 ± 2.6 vs. 17.4 ± 5.2 mL), peak AaDO2 (72.3 ± 7.3 vs. 46.3 ± 14.2 mm Hg), VE/VCO2 slope (70.1 ± 31.5 vs. 39.6 ± 9.6), and peak P(a-ET)tCO2 (13.9 ± 3.5 vs. 8.1 ± 3.6 mm Hg) were observed between patients with and without PH (p < 0.001). Patients with PH had significantly higher VDf/VT at rest, VT1, and at peak exercise (65.6 ± 16.8% vs. 47.2 ± 11.6%; p < 0.001) than those without PH. A cutoff value of 44 for VE/VCO2 slope had a sensitivity and specificity of 94.7 and 72.7%, while a cutoff value of 11 mm Hg for P(a-ET)CO2 in combination with peak AaDO2 >60 mm Hg had a specificity and sensitivity of 95.5 and 84.2%, respectively. Combining peak AaDO2 >60 mm Hg with peak VO2/body weight/min <16.5 mL/kg/min provided a sensitivity and specificity of 100 and 95.5%, respectively. Conclusion: This study provided initial data on CPET among patients having CPFE with and without PH. CPET can help noninvasively detect PH and identify patients at risk. AaDO2 at peak exercise, VE/VCO2 slope, peak P(a-ET)CO2, and peak VO2 were parameters that had high sensitivity and, when combined, high specificity.

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