Pulmonary Function
Spirometry values were significantly lower in the EP-BPD group than in the other groups (Table 2, Figure 2). There were no statistically significant differences in spirometry between the EP-noBPD and MLP groups. The percentage of patients with spirometry parameters below the lower limit of normal (LLN) (1.645 standard deviations below the predicted value) was significantly higher in the EP-BPD group than in the other groups (Table 2). The unadjusted analysis showed that the percentage of positive results in bronchodilator testing was higher in the EP-BPD group than in the other groups, but the differences were not statistically significant.
The adolescents in the EP-BPD group had significantly greater air-trapping (represented by the ratio RV/TLC) than those in the MLP group. There were no differences in the remaining plethysmographic parameters between groups. DLCO values were significantly lower in the EP groups, regardless of whether participants had BPD, than in the MLP group. KCO values were also lower in the EP groups, but the differences only reached significance between the EP-NoBPD and MLP groups (E-table 2).
In the adjusted regression models, the percentage of positive results in bronchodilator testing became significantly higher in the EP-BPD group than in the other groups (E-table 3). In addition, RV/TLC was significantly higher in the BPD group than in the EP-noBPD group (E-table 4). Moreover, pulmonary function differences between groups remained similar to those found in the unadjusted analysis.
The adolescents in the “high severity” BPD subgroup had significantly worse spirometry results than those in the “low severity” BPD subgroup, but there were no differences in lung volume or diffusion measurements. These 2 subgroups were comparable in terms of GA and birth weight (E-table 5).