Results
The characteristics of the 43 children/adolescents at their initial evaluation are described in Table 1. At their second visit, the adolescents had a median age of 14.9 [13.5; 16.2] years. The figure 1 describes the change in DLCO and its components between the two visits. Overall, a significant decrease in DLCO indices is evidenced that is also true for spirometry indices with the exception of FEV1/FVC: at the second evaluation, the FEV1 % predicted was 87 % [77; 94] (versus visit 1, see Table 1, p=0.0004), the FVC % predicted was 91 % [84; 98] (versus visit 1, p=0.0011) and the FEV1/FVC % predicted was 96 % [90; 99] (versus visit 1, p=0.0656).
The median decrease from visit 1 to visit 2 in DLCOcorrected % predicted was 46% [31; 70], in KCOcorrected % predicted was 43% [29; 59] and in VA % predicted was 14% [4; 25]. The conditional change scores of DLCO indices are provided in the online supplement further demonstrating the decrease in VA, KCO, KCOcorrected and DLCOcorrected. The decrease in DLCO corrected was independently related to both KCO and VA decreases in a multiple regression (r2=0.92; p<0.0001). The DLCOcorrected % predicted change negatively correlated with serum LDH while the KCOcorrected % predicted change positively correlated with baseline Vc/VA (R= -0.33, p=0.036 and R= 0.34, p=0.037; respectively, see figure in the online supplement). These decreases also positively correlated with their baseline (visit 1) % predicted values (R= 0.85; p<0.0001 for DLCO and R= 0.58; p=0.0002 for KCO, respectively).
The decrease in KCOcorrected % predicted was more severe in boys than in girls: 56% [41; 64] versus 37 % [20; 56], p=0.0189.