Analysis of Factors Associated with SMPP Progression to OB
Of 47 (46.8%) pediatric SMPP patients with mucous emboli, 22 patients
developed OB and no OB was found in children without mucous emboli;
thus, OB incidence in children with mucous emboli was significantly
higher than in children without mucous emboli (P < 0.001). All
8 cases (100%) with plastic bronchitis determined via bronchoscopy
exhibited different degrees of OB. During the convalescent stage, OB
occurred in 4 of 183 cases (2.2%) reporting two or fewer prior
bronchoscopies and 18 of 30 cases (60%) with at least 3 prior
bronchoscopies. The incidence of OB in children with two or fewer
bronchoscopies was significantly lower than OB incidence in children
with at least three prior bronchoscopies (P < 0.001).
Importantly, of 142 children (6.3%) who had the first bronchoscopy
within 10 days of disease onset, 9 developed OB (6.3%); of 71 children
who had their first bronchoscopy on or after 10 days of disease onset,
13 (76.5%) developed OB. Therefore, OB incidence of children undergoing
bronchoscopy within 10 days of disease onset was significantly lower
than that of children undergoing bronchoscopy at or after 10 days
post-disease onset (P < 0.007). Moreover, the average chest CT
number for children with acute stage obstructive bronchitis was 26 u,
while the average CT number for children without OB was 19 u. Thus,
chest CT values of children with OB were significantly higher than those
of children without OB, with the difference between groups reaching
statistical significance (P < 0.05). Notably, OB was found in
all 6 cases afflicted with necrotizing pneumonia (100%), as detected
via pulmonary imaging (Table 2, Figure 3).