Association of Oxygen Therapy with the Natural Disease Progression of Cystic Fibrosis: A Multi-State Model of the European Cystic Fibrosis Society Patient Registry

Background: Association between dependence on oxygen therapy (OT) and natural disease progression in people with cystic fibrosis (pwCF) has not been estimated yet. The aim of this study is to understand the prognosis for pwCF on OT, evaluating how the transition probabilities from being alive without lung transplantation (LTx) to LTx and to death, and from being alive after LTx to death change in pwCF with and without OT. Methods: We used 2008– 2017 data from the 35-country European CF Society Patient Registry. A multi-state model was fitted to assess the effects of individual risk factors on transition probabilities. Results: We considered 48,343 pwCF aged from 6 to 50 years. OT (HR 5.78, 95% CI: 5.32– 6.29) and abnormal FEV1 (HR 6.41, 95% CI: 5.28– 7.79) were strongly associated with the probability of having LTx; chronic infection with Burkholderia cepacia complex (HR 3.19, 95% CI: 2.78– 3.67), abnormal FEV1 (HR 5.00, 95% CI: 4.11– 6.08) and the need for OT (HR 4.32, 95% CI: 3.93– 4.76) showed the greatest association with the probability of dying without LTx. Once pwCF received LTx, OT (HR 1.75, 95% CI: 1.41– 2.16) and abnormal FEV1 (HR 1.63, 95% CI: 1.18– 2.25) were the main factors associated with the probability of dying. An association of gross national income with the probability of receiving LTx and with the probability of dying without LTx was also found. Conclusion: Oxygen therapy is associated with poor survival in pwCF with and without LTx; harmonization of CF care throughout European countries and minimization of the onset of pulmonary gas exchange abnormalities using all available means remains of paramount importance.