Predictors and Outcome of Low Initial Forced Expiratory Volume in 1 Second Measurement in Children with Cystic Fibrosis.

Objective: To identify the characteristics of children with cystic fibrosis with low initial forced expiratory volume in 1 second (FEV₁) % predicted and to investigate their outcome. Study design: Patients were categorized into low or high initial FEV₁ groups using cluster analysis. Comparisons of the demographic and clinical data were performed between the 2 groups. Results: From 122 children, 21 clustered into the low and 101 into the high FEV₁ group. The mean FEV₁ was 69% ± 12% predicted for the low and 95% ± 12% predicted for the high FEV₁ group (P < .001). The low FEV₁ group had lower body mass index percentiles (P = .003), were hospitalized more frequently (P = .001), and had been on dornase alfa longer (P = .006). Low FEV₁ group had more patients with positive cultures for Pseudomonas aeruginosa (P = .002) and Stenotrophomonas maltophilia (P < .001) and had more total number of cultures positive for mucoid P aeruginosa (P = .009) and methicillin resistant Staphylococcus aureus + P aeruginosa (P = .005). The low FEV₁ group continued to have low FEV₁ measurements, their FEV₁ declined slower, required more hospitalizations per year (P = .01), and had more cultures for mucoid (P = .003) and nonmucoid P aeruginosa (P = .02) ± methicillin resistant S aureus (P = .002) in comparison with the high FEV₁ group. Poor adherence was associated with lower initial FEV₁ values in females, and early, rapid decline of FEV₁ in males. Conclusions: Some children with cystic fibrosis may present with poor lung function early in life and continue to have subnormal lung function associated with reduced body mass index, more frequent hospitalization, and higher rates of infection. Such children may benefit from careful evaluation and close follow-up. [Copyright &y& Elsevier]