Effects of COVID-19 infection in patients with autoimmune pulmonary alveolar proteinosis: a single-center study

<bold>Background and objective:</bold> Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare interstitial lung disease. COVID-19 is associated with worse prognosis in previous lung diseases patients. But the prognosis of aPAP patients after infection with COVID-19 is unclear. In this study, we aim to explore the clinical outcomes of aPAP patients infected with COVID-19. <bold>Methods:</bold> The patients included in the study were all from the Chinese PAP registry study follow-up cohort. A post-COVID-19 infection health status questionnaire and telephone follow-up will be administered to all registered patients through the Xingshulin MedClip app and completed between January 1 and February 15, 2023. <bold>Results:</bold> A total of 39 aPAP patients were included in this study. 30.77% patients had a decrease in oxygen saturation after COVID-19 infection. We compared the two groups of patients with or without decreased oxygen saturation after COVID-19 infection and found that patients who had previous oxygen therapy (decreased oxygen saturation vs. non decreased oxygen saturation: 6/12 vs. 4/27, P = 0.043), with lower baseline arterial oxygen partial pressure (74.50 ± 13.61 mmHg vs. 86.49 ± 11.92 mmHg, P = 0.009), lower baseline DLCO/VA% [77.0 (74.3, 93.6) % vs. 89.5 (78.2, 97.4) %, P = 0.036], shorter baseline 6MWD [464 (406, 538) m vs. 532 (470, 575) m, P = 0.028], higher disease severity score (P = 0.017), were more likely to have decreased oxygen saturation after COVID-19 infection. <bold>Conclusion:</bold> aPAP patients with poor baseline respiration have a higher probability of hypoxia after COVID-19 infection, but fatal events were rare.