Cystic fibrosis survival: the changing epidemiology

Tracking patient outcomes using cystic fibrosis (CF) national data registries, we have seen a dramatic improvement in patient survival. As there are multiple ways to measure survival, it is important for readers to understand these different metrics in order to clearly translate this information to patients and their families. The aims of this review were to describe measures of survival and to review the recent literature pertaining to survival in CF to capture the changing epidemiology.

Although survival has improved on a population level, several individual factors continue to impact survival such as sex, age of diagnosis, ethnic background and lung function. Survival estimates, conditional on surviving to a specified age, are more relevant to individuals living with CF today and are higher than the reported overall median age of survival. There is some evidence to suggest that newborn screening (NBS) has resulted in prolonged survival in CF.

Prognosis in CF is often described by reporting the median age of survival, the median age of death, the median survival conditional on living to a certain age and the survival by birth cohort. Each of these metrics provide useful information depending on an individual's personal disease trajectory. The median age of survival continues to increase in CF in many countries while mortality rates are decreasing. Several factors have been associated with worse survival such as female sex, ethnicity, worse nutritional status, lower lung function and microbiology. When comparing survival between countries, one needs to ensure that similar data collection and processing techniques are used to ensure valid and robust comparisons.