More than half of British babies born with cystic fibrosis today will reach the age of 50, according to a new forecasting method.
The same is true of CF patients who have reached the age of 30 today, researchers said. Reaching 30 is a milestone that signals another 20 years of survival, the team said.
An article on the new forecasting method, and some of the predictions based on it, appeared in the Journal of Cystic Fibrosis. The title is “Up-to-date and projected estimates of survival for people with cystic fibrosis using baseline characteristics: A longitudinal study using UK patient registry data.”
CF is an inherited disease that causes persistent lung infections and worsens patients’ ability to breathe over time. Patients’ survival has greatly improved in recent decades due to advances in treatment and care.
The current forecasting tool is median survival age at birth. Its application is limited to patients beyond a certain age, however. In addition, current survival estimates do not take into account the full range of patient characteristics, including their genetic background, and advances in treatment and care.
This prompted a group of researchers to create a new method for predicting survival in babies and older patients. They used the UK Cystic Fibrosis Registry, a database managed by the Cystic Fibrosis Trust, to obtain patient information. The registry, which covers almost all of Britain’s CF patients, includes long-term follow-up data.
In creating their new forecasting tool, the researchers took into account patients’ sex, CF-related genetic characteristics, age of diagnosis, and decreasing patient mortality trends.
The study’s ultimate goal was to “provide more individually relevant information on survival for people with CF in the U.K. and projections that are relevant for planning future health care resource needs,” the researchers wrote.
They used registry records from 2011 to 2015 to analyze 10,428 patients.
One finding was that men survived longer than women.
A number of other findings centered on whether a person had one or two copies of the most common CF genetic abnormality — the F508del mutation. People normally inherit two copies of a gene, one from their mother and one from their father. In the case of a mutation, sometimes there is one copy, and sometimes two.
If there was one copy, the older a person was when diagnosed with CF, the longer they survived, researchers found. In contrast, the number of copies had no effect on the survival of individuals diagnosed at birth.
Another finding was that men who were diagnosed at birth, and who had two copies of the mutation, survived a median of 46 years, versus 41 years for women.
Similarly, men diagnosed at age 5 with only one copy of the mutation lived a median of 57 years, compared with 51 for women.
If a man with two copies of the mutation lived to age 30, they were likely to continuing surviving until 52, researchers found. The figure was 49 for women.
Importantly, the analysis showed that between 2006 and 2015, CF death rates decreased by 2 percent a year. If this trend holds, its suggests that men with two copies of the F508del mutation will live until 65 and women to 56.
“These up-to-date survival statistics will be important to inform planning of healthcare services, given the evidence for continued improvements in survival in CF over time,” the researchers wrote.
The findings match previous research indicating that men with CF survive longer than women. “More research using longitudinal data is needed to elucidate the pathways to worse outcome for females,” the team wrote.
For patients beyond a certain age, measures such as lung function will be more relevant to survival forecasting than other characteristics, the researchers observed. They are working on adding these estimates to the registry.