WS4.1 Treatment burden in patients with CF and at least one class 4 or 5 mutation

Abstract

According to their disease-causing mechanism, many of the CF mutations can be grouped in one of five mutation classes. These partially explain the heterogeneous presentation of CF. Several studies have demonstrated that patients having at least one mutation of class 4 or 5, usually present with a milder phenotype. We wanted to compare disease severity and, especially, treatment burden between these patients and subjects with two class 1, 2 or 3 mutations. Therefore, we included all CF patients enrolled in the 2010 database of the Belgian CF Registry who could be assigned to one of these two cohorts. 271 children and 335 adults with 2 known class 1/2/3 mutations were included, plus 42 children and 49 adults with at least one class 4/5 mutation. In both age categories mean sweat chloride was significantly lower and age at diagnosis was higher in class 4/5 patients. Pancreatic insufficiency, chronic Pseudomonas infection and CF related diabetes were less common. Mean FEV1 was lower in adults with class 4/5 mutations. Independent of age, class 4/5 patients had a lower mean number of clinic visits, days in hospital, days with intravenous antibiotics; a lower proportion used rhDNASe, mucolytics, oral or inhaled antibiotics, azithromycin, and inhaled corticosteroids. This study confirms the milder phenotype seen in patients with CF and at least one class 4 or 5 mutation. In addition, we demonstrate their significantly lower treatment burden compared to patients who have two class 1/2/3 mutations. These findings contribute to providing better individual counseling at time of diagnosis for patients with CF.