Differences in disease expression between primary ciliary dyskinesia and cystic fibrosis with and without pancreatic insufficiency

Background: Impaired mucociliary clearance causes pulmonary disease in primary ciliary dyskinesia (PCD) and contributes to cystic fibrosis (CF) lung disease. Although the sinopulmonary disease is similar, morbidity and mortality are different. Both patients with PCD and patients with CF with pancreatic sufficiency (CF-PS) show no nutrient malabsorption and are diagnosed at a later age compared with patients with CF with pancreatic insufficiency (CF-PI). Methods: Clinical status, microbiology, FEV₁ , and high-resolution CT (HRCT) scans presented as total Brody score (CT-TBS) were compared for patients with PCD, CF-PI, and CF-PS, all treated at the same medical center, by the same team, and by a similar routine follow-up. Results: One hundred sixty-four patients, 34 with PCD, 88 with CF-PI, and 42 with CF-PS were enrolled. PCD was diagnosed at a similar age as CF-PS but significantly later than CF-PI. Mean FEV₁ % predicted was similar for the three groups. The rate of FEV₁ change with age in PCD was similar to CF-PS but significantly lower than in CF-PI. Severity of structural lung disease (CT-TBS) was similar for PCD and CF-PS and significantly higher in CF-PI. No correlation between TBS or Pseudomonas aeruginosa infection and FEV₁ in PCD was seen, whereas a negative correlation with FEV₁ was observed for both CF groups. Conclusions: Although in our study PCD was similar to CF-PS, the lack of correlation between FEV₁ and age, CT-TBS, and P aeruginosa infection in PCD suggests that impaired mucociliary clearance is not the only cause for inducing pulmonary damage in these diseases. Furthermore, a comparison of disease characteristics for PCD and CF should distinguish between CF-PI and CF-PS as different entities.