Objectives: There are few studies about survival in patients with Cystic Fibrosis (CF) under oxygen therapy (OT). Considering its clinical meaning and impact on patients\u2019 lifestyle, we aimed to determine how OT is associated with known prognostic factors and with lung transplantation (LTx) and death (D).
Methods:We considered patients 6450 years registered in the ECFSPR from 2008 to 2017. An illness-death multi-state model was fitted, denoting LTx as intermediate state. Cox\u2019s proportional hazard models were fitted using age as time scale and left truncation corresponding to age at entry into ECFSPR. Models were used to estimate transition intensities and OT hazard ratio (HR), adjusted for known prognostic factors (age, sex, insulin, Pseudomonas aeruginosa (Pa), Burkholderia cepacia (BC), BMI and FEV1% predicted).
Results: 58576 patients were included in the analysis and 7627 (13%) had OT during the follow-up. 27587 (47.6%) were females, 35784 (61.1%) were <18 yrs old, 5228 (10.6%) had FEV1 <40%predicted, 5185 (9.5%) were underweight (BMI z score < 122), 6386 (10.9%) used insulin, 14037 (26.9%) had Pa, 1236 (2.4%) had BC. During the follow-up, 2509 patients had LTx and 3091 patients died: 2338 before and 753 after LTx. From the multi-state model, patients in OT have higher probability of having LTx (HR = 12.9, 95% CI: 11.6\u201314.4). The HRof death for patients in OT is 7.8 (95% CI: 6.9\u20138.7) before LTX, while it is 1.4 (95% CI: 1.2\u20131.7) after LTx.
Conclusions: The need for oxygen therapy represents a turning point in patients\u2019 life, decreasing their chances of survival, with implications in the post LTX period yet. UndoubtedlyOT should be considered as a marker of CF disease severity, and patients with a supplemental oxygen requirement should have prompt and fully clinical reassessment. Preventing respiratory failure with oxygen requirement remains one of the main goals of CF care
