Lost in translation? Therapeutic contrasts in CF and non-CF bronchiectasis

Non-cystic fibrosis bronchiectasis is a significant cause of morbidity and mortality and its prevalence is increasing. Unlike CF, non-cystic fibrosis bronchiectasis (NCFB) is a heterogeneous disease, with a variety of predisposing factors and disease mechanisms implicated in its pathogenesis. However, the “vicious cycle” hypothesis is the generally accepted explanation for the evolution of bronchiectasis, both in CF as in NCFB.

Pharmacologic and nonpharmacologic therapies are used in CF and NCFB with varying success. The routine use of bronchodilator therapies or steroids in CF and NCFB is not recommended except when there is airflow reversibility or allergic bronchopulmonary aspergillosis. Long-term azithromycin consistently shows a reduction in exacerbations and as a consequence is widely used in patients with both CF and NCFB and is recommended for use in patients with and without Pseudomonas aeruginosa (PA) infection. The use of antibiotics in patients with NCFB is driven mostly by studies in patients with CF. In CF and NCFB, exacerbation frequency, lung function, and disease extent are worse in patients infected with PA. As in CF, eradication of PA in NFCB should be attempted, especially following initial colonization. Inhaled antibiotics reduce airway bacterial load and associated airway inflammation in NCFB. Unlike data in the CF population, where inhaled antibiotics have been shown to reduce exacerbations and hospital admissions, studies in NCFB did not persuasively demonstrate a reduction in exacerbation frequency. Hypertonic saline benefits patients with CF by improving quality of life, reducing pulmonary exacerbations and improving lung function. Although there are no strong data or recommendations for routine use of hypertonic saline in NCFB, some patients seem to benefit from this therapy. Aerosolized dornase alpha reduces mucus viscosity, improves lung function, and reduces hospitalizations in patients with CF but in NCFB was found to cause greater reductions in FEV1.

Many aspects of the management of bronchiectasis in patients with no CF have thus been based on the experience gained from and the more extensive research studies performed in CF. However, therapies for NCFB cannot simply be extrapolated from CF, and some treatments, such as the use of inhaled DNase, may actually result in harm. The differences in efficacy likely result from differences in pathophysiology and patient demographics. Clinical studies that specifically target patients with NCFB are sorely needed.