Epidemiology

Cystic fibrosis is the most common life-shortening genetic disease in the Caucasian population. It is an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). The CFTR gene encodes the CFTR protein, which is a chloride channel expressed in many epithelial cells.

Cystic fibrosis is a multi-system disease affecting organs and tissues where CFTR is expressed. The most common clinical features are exocrine pancreatic insufficiency and bronchiectasis with chronic airway infection, leading to respiratory failure and premature death. Cystic fibrosis-related symptoms appear throughout life, with great overlap and variability of symptoms and timing from patient to patient.

Symptomatic treatment, with airway clearance and antibiotic therapy for lung disease, and pancreatic enzymes to compensate for exocrine pancreatic insufficiency, have improved the prognosis for cystic fibrosis patients during the last 30 years. Since 2012 however, new drugs aimed at restoring the CFTR protein function are becoming available and are likely to dramatically change cystic fibrosis care and prognosis over the coming decades [O'Sullivan and Freedman, 2009; Elborn, 2016].

Cystic fibrosis affects around 75,000 individuals worldwide. They are primarily of European descent, although the disease has been reported in all races and ethnicities [Cutting, 2015].

In European countries the prevalence of cystic fibrosis was calculated to range from 0.104 per 10,000 in Latvia to 2.98 per 10,000 in Ireland. The mean prevalence was reported as 0.737 per 10,000 in the 27 EU countries, which is similar to the value of 0.797 per 10,000 found in the United States [Farrell, 2008]. The estimated incidence of cystic fibrosis ranges from 1:25000 in Finland to 1:1353 in Ireland [Farrell, 2008], with an overall incidence in Europe between 1:2000 to 1:3000 [Salvatore et al., 2011].

Prevalence of cystic fibrosis in European countries [Farrell, 2008].

Prevalence of cystic fibrosis in European countries [Farrell, 2008].

Ethnicity is important in determining the incidence of cystic fibrosis: in the United States the incidence of cystic fibrosis was estimated at 1:3200 in Caucasians and 1:15,000 in non-Caucasians [Salvatore et al., 2011].

Cystic fibrosis used to be a fatal disease of childhood but with the improvement of care and treatment, the prognosis has improved dramatically over the last 30 years. There are still disparities; young females have a worse prognosis and lower median survival compared with their male counterparts [McIntyre, 2013]. The current median survival is 30–35 years and the expected survival of a child born today with cystic fibrosis is 50 years [MacKenzie et al., 2014]. The number of adults with cystic fibrosis is currently larger than the number of children with cystic fibrosis in several countries. Forecasts for 2025 in western European countries indicate an overall increase in the number of patients with cystic fibrosis by approximately 50%, with an increase in the number of adults with cystic fibrosis by approximately 75% [Burgel et al., 2015].