Study participants
Between January 2006 and December 2017, 428 children received allogeneic
HSCT at Asan Medical Center. A detailed description for study
participants is provided in the online supplement . In the
present study, 21 children met lung function criteria modified from the
National Institutes of Health consensus guidelines for diagnosis of BOS
(E-figure 1) 11,20,21. No subject has concurrent
pulmonary infection. In addition, all subjects underwent chest CT scans,
and 13 children showed air trapping, small airway thickening, or
bronchiectasis. A lung perfusion/ventilation scan was performed on eight
children who showed no clear evidence of BOS according to the CT
results. Of those eight, five had heterogeneous multiple matched
perfusion defects. Lung biopsies were performed on nine children, and
constrictive bronchiolitis was confirmed in all nine. Echocardiograms
showed that all 21 patients displayed normal heart function at the time
of BOS diagnosis.
The median observation period for all subjects after BOS diagnosis was
34.4 months (IQR, 11.5-62.0 months). In our current analysis, pulmonary
function tests (PFTs) were gathered during 24 months after BOS
diagnosis, and CT values were gathered during 12 months after diagnosis.
All subjects started treatment immediately upon diagnosis. All subjects
received 6 to 17 cycles of methylprednisolone (mPD) (i.v. 20mg/kg/day
for 3 days, with an interval of 1 month) except one subject who died
within 6 months after BOS diagnosis. The median mPD pulse therapy period
for all subjects was 12.0 months (IQR: 7.5-12.0 months) (E-table 1). A
detailed description is provided in the online supplement .
Diagnosis and treatment of BOS and lung function monitoring followed the
Pediatric Hemato-oncology Division of Asan Medical Center protocol
regarding BOS after HSCT, which was developed with the Pediatric
Pulmonology Division in 2011.
We divided subjects into two groups according to BOS prognosis and
compared the clinical characteristics, lung function parameters, and
chest CT findings between the good and poor prognosis groups. The poor
prognosis group included patients who had died or required lung TPL
(hereafter labeled Group 1) and Group that had required
O2 therapy after BOS diagnosis (hereafter labeled Group
3), and the good prognosis group included survivors that did not require
lung TPL (hereafter labeled Group 2) or Group that did not require
O2 therapy after BOS diagnosis (hereafter labeled Group
4). O2 therapy was defined as O2 therapy
for more than 1 day due to dyspnea after BOS diagnosis and
O2 therapy was applied when dyspnea was accompanied by
less than 90% of SPO222.