Progression of lung disease in primary ciliary dyskinesia: is spirometry less accurate than CT?

Despite its extensive use, there is no evidence that spirometry is useful in the assessment of progression of lung disease in primary ciliary dyskinesia (PCD). We hypothesize that high-resolution computed tomography (HRCT) is a better indicator of PCD lung disease progression than spirometry. We retrospectively evaluated two paired spirometry and HRCT examinations from 20 PCD patients (age, 11.6 years; range, 6.5-27.5 years). The evaluations were performed in stable state and during unstable lung disease. HRCT scans were scored blind by two raters. Compared to the first assessment, at the second evaluation spirometry did not change while HRCT scores significantly worsened (P < 0.01). Age was significantly related to HRCT total (r = 0.5; P = 0.02) and bronchiectasis scores (r = 0.5; P = 0.02). At both evaluations, HRCT total score correlated with FEV(1) (r = -0.5, P = 0.01; r = -0.7, P = 0.001, respectively) and FVC Z scores (r = -0.6, P = 0.006; r = -0.7, P = 0.001, respectively), and bronchiectasis score was related to FEV(1) (r = -0.5, P = 0.03; r = -0.6; P = 0.002, respectively) and FVC Z scores (r = -0.6, P = 0.008; r = -0.7, P = 0.001, respectively). No relationship was found between the change in HRCT scores and the change in spirometry. In PCD, structural lung disease may worsen despite spirometry being stable.