Methods
This prospective national observational study targeted centers for
pediatric pulmonology from all regions of the Czech Republic. From
January to June 2021, 11 pediatric pulmonologists enrolled all children
aged 2 to 18 years with persistent respiratory symptoms after COVID-19
referred by pediatricians from inpatient or outpatient settings.
Inclusion criteria were: (1) presence of dyspnea at rest or on exertion,
cough, or chest pain twelve or more weeks after infection with severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2); and (2)
documentation of preceding SARS-CoV-2 infection by positive PCR test or
detection of significant elevation of antibodies; and (3) absence of any
pre-existing chronic respiratory disease. We applied a standardized
protocol to evaluate structural and functional anomalies and exclude
alternative diagnoses. Initially, medical history, physical examination,
lung function testing comprising spirometry, fraction of exhaled nitric
oxide (FeNO), diffusing capacity (DLCO), and 6-minute walk test (6MWT),
plain chest radiograph, and blood tests were performed in all enrolled
children. Laboratory tests comprised blood count, basic biochemistry and
allergy panel, D-dimer levels, and SARS-CoV-2 antibodies. In children
with abnormal results of the initial panel, we considered individually
an extended spectrum of investigative methods: chest ultrasound, spiral
chest CT scan with high-resolution reconstruction, CT-pulmonary
angiograms, ventilation/perfusion (VP) lung scan. For all enrolled
subjects, we scheduled at least two outpatient visits within six months.
We compared numerical variables using One-way ANOVA and categorical
variables with Fisher’s exact test. All analyses were performed using
IBM SPSS Statistics software version 21. This study was approved by the
Ethics Committee with multicentric competence (ID A-21-01).