RATIONALE: Chest computed tomography (CT) is the gold standard for demonstrating cystic fibrosis (CF) airways disease. However, there are no standardised outcome measures appropriate for children under 6 years.

OBJECTIVES: We developed the Perth-Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF), a quantitative measure of airways disease, and compared it to the commonly used CF-CT scoring method.

METHODS: CT scans from the Australian Respiratory Early Surveillance Team for CF (AREST CF) cohort in Western Australia were included. PRAGMA-CF was performed by annotating a grid overlaid on ten axial slices for the presence of bronchiectasis, mucous plugging or other airway abnormalities (inspiratory scans) and trapped air (expiratory scans). The separate proportions of total disease (%Dis), bronchiectasis (%Bx) and trapped air (%TA) were determined. Thirty scans were used for observer reliability, and thirty paired scans obtained at 1 and 3-years old were used for comparison with a validated standard and biological plausibility.

MEASUREMENTS AND MAIN RESULTS: Intraobserver, intraclass correlation coefficients (95% confidence interval) for %Dis, %Bx and %TA were 0.93 (0.86 - 0.97), 0.93 (0.85 - 0.96) and 0.96 (0.91 - 0.98), respectively. The change in %Dis (p = 0.004) and %Bx (p = 0.001) with PRAGMA-CF was related to neutrophil elastase (NE) presence at age 3, whereas only the change in bronchiectasis score was related to NE (p < 0.001) with CF-CT. Sample size calculations for various effect sizes are presented.

CONCLUSIONS: PRAGMA-CF is a sensitive and reproducible outcome measure for assessing the extent of lung disease in very young children with CF.