Supplementary Material for: Pulmonary Recovery 12 Months after Non-Severe and Severe COVID-19: The Prospective Swiss COVID-19 Lung Study

<b><i>Background:</i></b> Lung function impairment persists in some patients for months after acute coronavirus disease 2019 (COVID-19). Long-term lung function, radiological features, and their association remain to be clarified. Objectives: We aimed to prospectively investigate lung function and radiological abnormalities over 12 months after severe and non-severe COVID-19. <b><i>Methods:</i></b> 584 patients were included in the Swiss COVID-19 lung study. We assessed lung function at 3, 6, and 12 months after acute COVID-19 and compared chest computed tomography (CT) imaging to lung functional abnormalities. <b><i>Results:</i></b> At 12 months, diffusion capacity for carbon monoxide (DLCO_corr) was lower after severe COVID-19 compared to non-severe COVID-19 (74.9% vs. 85.2% predicted, <i>p</i> &lt; 0.001). Similarly, minimal oxygen saturation on 6-min walk test and total lung capacity were lower after severe COVID-19 (89.6% vs. 92.2%, <i>p</i> = 0.004, respectively, 88.2% vs. 95.1% predicted, <i>p</i> = 0.011). The difference for forced vital capacity (91.6% vs. 96.3% predicted, <i>p</i> = 0.082) was not statistically significant. Between 3 and 12 months, lung function improved in both groups and differences in DLCO between non-severe and severe COVID-19 patients decreased. In patients with chest CT scans at 12 months, we observed a correlation between radiological abnormalities and reduced lung function. While the overall extent of radiological abnormalities diminished over time, the frequency of mosaic attenuation and curvilinear patterns increased. <b><i>Conclusions:</i></b> In this prospective cohort study, patients who had severe COVID-19 had diminished lung function over the first year compared to those after non-severe COVID-19, albeit with a greater extent of recovery in the severe disease group.

***背景：*** 部分急性新型冠状病毒肺炎（coronavirus disease 2019, COVID-19）患者在发病后数月仍持续存在肺功能损害，其长期肺功能状态、放射学特征及二者的关联仍有待阐明。本研究旨在前瞻性探究重型与非重型COVID-19患者发病后12个月内的肺功能与放射学异常情况。
***方法：*** 本研究纳入瑞士COVID-19肺部研究的584例患者，于急性COVID-19发病后3、6及12个月时评估其肺功能，并将胸部计算机断层扫描（computed tomography, CT）影像结果与肺功能异常情况进行对比。
***结果：*** 发病后12个月时，重型COVID-19患者的校正一氧化碳弥散量（diffusion capacity for carbon monoxide, DLCO_corr）较非重型患者更低（预计值百分比分别为74.9%与85.2%，*P*<0.001）。类似地，重型COVID-19患者的6分钟步行试验（6-minute walk test）最低血氧饱和度及肺总量亦更低（分别为89.6%与92.2%，*P*=0.004；预计值百分比分别为88.2%与95.1%，*P*=0.011）。用力肺活量（forced vital capacity）的组间差异（预计值百分比分别为91.6%与96.3%，*P*=0.082）无统计学意义。在3至12个月期间，两组患者的肺功能均有所改善，非重型与重型COVID-19患者之间的DLCO差异逐渐缩小。对12个月时接受胸部CT检查的患者进行分析可见，放射学异常与肺功能降低存在相关性。尽管放射学异常的总体范围随时间推移有所减小，但马赛克衰减征（mosaic attenuation）与线条状影（curvilinear patterns）的出现频率有所升高。
***结论：*** 本前瞻性队列研究显示，与非重型COVID-19患者相比，重型COVID-19患者在发病后1年内的肺功能更差，但重型患者的恢复幅度更大。