Phenotypic Features Compared According to VHI % Quartiles
Children with VHI % in the upper quartile had phenotypic features
unique from those in children in the lower quartile (Table I and Figure
2). Children with VHI % in the upper 75th %ile had
greater non-white racial/ethnic backgrounds (73% vs 20%, p = .006),
more lifetime ICU admissions (range of 0-6 vs 0-4, p = .04), and were
treated with twice the number of daily controller medications (4.0 vs
2.0 , p = .02) compared to children in the lower 25th%ile.
Accordingly, children with VHI % in the upper 75th%ile had reduced lung function with greater airflow limitation and
bronchodilator responsiveness compared to children in the lower
25th %ile (Table I). Differences included lower
pre-BD FEV1 % (80 vs 100, p = .02), and lower pre-BD
FEV1/FVC % (83 vs 94, p = .04) in children with the
upper 25th %ile VHI %. Both the pre- and post-BD
FEF25-75 % (55 vs 89 and 61 vs 91, respectively, p
< .05 for both) were less than mid-flows in children with VHI
% in the lower 25th %ile. Furthemore children with
VHI % in the upper 75th %ile had overall greater
bronchodilator reversibility, and the % change in the
FEV1 % from baseline was higher in the 75th versus
25th-75th %iles (22 vs 11, p =
.01).
VHI % sub-groups likewise had difference in the magnitude of type 2
inflammatory markers (Table I). Children with VHI % in the
75th %ile had higher absolute eosinophil counts (620
cells/ ul vs 220 cells/ ul blood, p = .001), a higher proportion with
absolute eosinophil counts ≥ 300 cells/ul blood (87% versus 20%, p =
.001) and higher FeNO (36 ppb vs 22 ppb, p = .03) compared to lower
%iles. VHI % sub-groups did not differentiate total IgE and the number
of positive specific IgE tests. Overall correlations between VH
indicators and scaled outcomes were modest to poor (See E-supplement,
results and Table E-2).