Europe's cystic fibrosis population became mostly adult in a single decade

Cystic fibrosis used to be a paediatric disease in the demographic sense: most patients were children, because most patients did not become adults. An analysis of the European Cystic Fibrosis Society Patient Registry, published in The Lancet Respiratory Medicine this month, documents the decade in which that stopped being true across Europe [s1].

The registry collects annual data on more than 55,000 people with cystic fibrosis [s1]. This analysis used longitudinal data from 20 European countries with high patient coverage — above 85% — from 2014 to 2024, representing 80% of the whole registry cohort [s1]. Differences in annual cross-sectional estimates were assessed using regression models [s1].

The demographic shift

Between 2014 and 2024, the number of adults with cystic fibrosis in the analysed cohort increased by 45.0% [s1]. Over the same period, adults went from 50.9% of the total cystic fibrosis population to 60.5% [s1]. The number of adults older than 30 nearly doubled [s1].

That is a population changing shape, not just growing. A cohort where six in ten patients are adults and the over-30 group is the fastest-growing segment has different clinical needs from one built around paediatric clinics, and the paper's central argument is about exactly that mismatch [s1].

Lung function, weight, infection

Among adults who had not received a transplant, mean percent predicted FEV1 — the standard measure of airflow obstruction — improved from 66.1% to 78.8% across the decade, with most of the gain occurring after 2020 [s1]. The p value for that change was below 0.0001 [s1].

A shift of that size in mean predicted lung function, at population level, is a large effect in a progressive lung disease where the historical expectation was steady annual decline. The timing of the gain — concentrated after 2020 — is the part that carries the causal hint.

Chronic Pseudomonas aeruginosa infection declined significantly over the period [s1]. Mean body mass index increased significantly, halving the proportion of people who were underweight [s1]. Both changes reached p below 0.0001 [s1].

What the authors attribute it to

Uptake of elexacaftor-tezacaftor-ivacaftor — the triple CFTR modulator combination usually shortened to ETI — rose from 2% of the cohort in 2019 to 71% in 2024 [s1]. The largest improvements in health indicators were seen in individuals with at least one variant responsive to ETI [s1].

The authors' interpretation is that the expansion of the adult population is due to marked improvements in treatment, particularly following the availability of ETI triple therapy from 2018-19 onwards [s1], and that the improvements observed are consistent with substantial effects from improved care and CFTR modulators [s1].

That framing is deliberately careful, and it should stay careful in the retelling. This is registry data, not a trial. Nobody was randomised. The period covered also includes the pandemic, which changed infection exposure, clinic attendance and physical activity for people with chronic lung disease in ways that are hard to disentangle from drug effects. The concentration of gains among ETI-responsive genotypes is the strongest internal evidence that the modulators are doing much of the work, but it is a within-cohort comparison, not a controlled one.

The complications that went the other way

The less-quoted half of the result is that not everything improved. Age-related complications, such as malignancy, increased across the decade, while cystic-fibrosis-specific complications and insulin-treated diabetes declined [s1].

This is what success looks like in a genetic disease: the disease-specific problems recede and the problems of ageing arrive. A population that used to die before accumulating cancer risk now accumulates it. Nothing in the data suggests the modulators cause malignancy; the straightforward reading is that more people are living long enough for age-related disease to appear.

It also means that cystic fibrosis care is becoming, in part, general adult medicine — cancer screening, metabolic monitoring, comorbidity management — delivered by services historically organised around infection control and nutrition.

Limits

Registry analyses inherit the completeness of their inputs. Restricting to countries with above 85% coverage mitigates that but does not eliminate it, and it also means the result describes 20 European countries rather than Europe as a whole [s1]. Countries excluded for low coverage are not a random sample; they tend to be those with less developed specialist services, where modulator access has also been slower.

The analysis reports annual cross-sectional estimates compared over time, not individual trajectories, so a rising mean lung function partly reflects who is in the denominator each year as well as how existing patients are doing [s1].

The study reports no funding [s1].

What to watch

Two questions follow directly. The first is whether the improvement curve flattens now that ETI uptake has reached 71% — the remaining gains have to come from somewhere else [s1]. The second is what happens to people whose variants are not responsive to ETI — a group the registry can identify, since the largest improvements were confined to those with at least one responsive variant [s1], and whose outcomes will increasingly diverge from the cohort mean.

Sources

• [s1] Clinical characteristics and outcomes in the adult cystic fibrosis population in Europe from 2014 to 2024: analysis of the European Cystic Fibrosis Society Patient Registry — The Lancet Respiratory Medicine, published online 3 June 2026. https://doi.org/10.1016/S2213-2600(26)00149-9