Infant spirometry as a predictor of lung function at early childhood in cystic fibrosis patients.

BACKGROUND: Infant pulmonary function testing using the raised volume rapid thoracoabdominal compression (RVRTC) technique requires sedation and is time consuming. Many cystic fibrosis (CF) centers do not have access to equipment and the utility of routine testing remains to be determined. We aimed to assess whether RVRTC tests performed during infancy predict spirometry at early school age. METHODS: The RVRTC-based forced expiratory flow measures in infants were compared to the first adequately performed spirometry at school age. All tests were carried out during routine clinic visits and expressed as age related z-scores; only test occasions where patients were considered stable were included in the analysis. RESULTS: 47 patients had useable infant RVRTC as well as matching school age spirometry data. There was weak correlation between infant FEV0.5 and early school age FEV1 (R = 0.29, p = 0.05). Four infants had significantly low zFEV0.5 (zFEV0.5 < -1.96), of which one of those remained under that limit at childhood. Changes in spirometry between infancy and early childhood were negatively correlated to baseline FEV0.5 (R = 0.61 p<0.001) reflecting that the change was driven by where individuals started off with. There was no difference in clinical characteristics between those improving, those with stable or deteriorating in lung function. CONCLUSION: Infant RVRTC measures were not predictive of pulmonary function in early school age, likely due to the high proportion of measures of forced expiratory flows within the normal range at both time points.

The effect of dornase alfa on ventilation inhomogeneity in patients with cystic fibrosis.

Outcome measures to assess therapeutic interventions in cystic fibrosis (CF) patients with mild lung disease are lacking. Our aim was to determine if the lung clearance index (LCI) can detect a treatment response to dornase alfa in paediatric CF patients with normal spirometry. CF patients between 6-18 yrs of age with FEV(1 )≥ 80% pred were eligible. In a crossover design, 17 patients received 4 weeks of dornase alfa and placebo in a randomised sequence separated by a 4-week washout period. The primary end-point was the change in LCI from dornase alfa versus placebo. A mixed model approach incorporating period-dependent baselines was used. The mean ± sd age was 10.32 ± 3.35 yrs. Dornase alfa improved LCI versus placebo (0.90 ± 1.44; p = 0.022). Forced expiratory flow at 25-75% expired volume measured by % pred and z-scores also improved in subjects on dornase alfa (6.1% ± 10.34%; p = 0.03 and 0.28 ± 0.46 z-score; p = 0.03). Dornase alfa significantly improved LCI. Therefore the LCI may be a suitable tool to assess early intervention strategies in this patient population.