Background
Coronavirus disease 2019 (COVID-19) has been spreading worldwide since
the first outbreak in China, in December 2019. The Radiological Society
of North America reported that consolidation, reserve halo sign, and
other findings of organizing pneumonia were found in the late phase of
COVID-191. In general, the treatment for secondary
organizing pneumonia (SOP) is similar to that for cryptogenic organizing
pneumonia (COP). The British Thoracic Society guidelines suggested a
steroid pulse therapy (SPT) for some cases with fulminant
COP2. On the other hand, a previous report showed that
systemic corticosteroids delayed viral shedding and that they were
harmful for other coronaviruses3. Therefore, a routine
use of systemic corticosteroids is not recommended for viral infections
at this time. However, some reports suggested that the steroid therapy
might suppress a cytokine storm by COVID-194. One
retrospective study showed that the treatment with methylprednisolone
for COVID-19 reduced mortality in some cases4. SPT was
assumed to be effective in the late phase for SOP with respiratory
failure. This study aimed to investigate the efficacy and safety of SPT
for patients with SOP and respiratory failure due to COVID-19.