In adults with cystic fibrosis (CF), pancreatic status — that is, being pancreatic sufficient vs being pancreatic insufficient — has been shown to have a pronounced effect on the average rate of decline in lung function. An analysis of UK data from the National CF Registry was conducted between 2015 and 2017 and the results were published in the Journal of Cystic Fibrosis.

Investigators sought to establish the national rate of decline in percent predicted forced expiratory volume in 1 second (FEV1) in adult patients with CF in the United Kingdom who were attending specialist care centers. In their analysis, age, sex, and pancreatic status were all taken into account. All values for ppFEV1 were reported as the mean and the difference in percent predicted FEV1 between pancreatic sufficient and pancreatic insufficient adults with CF, which were compared via use of a t-test.

A total of 5554 adults with CF were included in the dataset, with 9 of them excluded from the analysis because their rate of change in percent predicted FEV1 was >150%. Overall, 54.5% of the participants were male and 45.5% of them were female. The mean patient age was 31.5±11.1 years. The majority of the participants (83.3%) were taking pancreatic supplements, with only 16.5% of them classified as being pancreatic sufficient. The pancreatic status was unknown in 10 of the patients.

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The overall annual decline in percent predicted FEV1 was -1.52% (95% CI, -1.66% to -1.38%) and -0.55% (95% CI, -0.86% to -0.23%) in pancreatic insufficient vs pancreatic sufficient adult patients, respectively. Additionally, differences were observed between the age groups. The most rapid rate of decline was reported in patients between ages 18 and 28 years who were taking pancreatic supplements.

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Variations were also reported with respect to gender. In men, the trend observed was that the annual rate of decline in percent predicted FEV1 decreased with increasing age, whereas in women, the rate of decline decreased with increasing age until the age of 51+ years, at which time the rate rose.

Furthermore, the pattern observed also differed in patients not taking pancreatic supplements. In women, the greatest annual rate of decline in percent predicted FEV1 was observed in those between ages 18 and 28 years, whereas in men, the greatest decrease was reported among those between ages 29 and 39 years. By 51+ years of age in men, however, a mean annual increase in percent predicted FEV1 was reported (95% CI, -0.23 to 1.95).

The investigators concluded that additional studies are warranted, which are designed to evaluate tools that compare an individual’s actual and predicted rate of decline in percent predicted FEV1. This would, hopefully, prove beneficial in triggering early intervention and preventing clinical deterioration in this patient population.


Caley L, Smith L, White H, Peckham DG. Average rate of lung function decline in adults with cystic fibrosis in the United Kingdom: data from the UK CF registry [published online May 4, 2020]. J Cyst Fibros. doi:10.1016/j.jcf.2020.04.008