Supplementary Material for: Ward-based high-flow nasal oxygen therapy in acute respiratory failure – a retrospective analysis of long-term mortality

Introduction: High-flow nasal oxygen therapy (HFNO) for acute respiratory failure (ARF) has been used in the intensive care units (ICU), but more recently also on respiratory wards (RW). Little data are available regarding in-hospital, short-term and long-term mortality in the latter setting.
Methods: We performed a retrospective analysis of patients ≥ 16 years old treated with HFNO on the RW between 01/2020 and 09/2022 with a follow-up until 09/2023. We grouped patients by main diagnosis and do-not-intubate (DNI) order. Cox proportional hazard models were used.
Results: We analysed 145 HFNO patients (36% women, median age 70 years [quartile range (Q1-Q3) 62-79)], BMI 25.8 [IQR 22.6-28.5] kg/m2) with ARF mostly due to COVID-19 (n=84, 57.9%), other pneumonia (n=25, 17.2%), and mixed other diagnoses (n=36, 25%). 71 patients (48.9%) started HFNO on ICU and continued on the RW, treatment was tolerated in 94% of patients. In-hospital mortality was 24.8% (n=35), of whom 33 patients had a DNI-order. The mortality rates after 30 days, 90 days and one year were 30% (n=44), 38% (n=54) and 43% (n=62). Long-term mortality did not differ between diagnostic groups (p>0.05), a higher BMI was associated with lower mortality [hazard ratio (HR) 0.95 (95% CI 0.91-0.99)]. A DNI-order and a palliative setting were associated with higher mortality [1 year: HR 3.03 (95% CI 1.15-7.69), p=0.024 and HR 4.01 (2.21-7.26), p<0.001].
Conclusion: In our cohort of patients with ARF treated with HFNO, the underlying diagnosis of ARF was not associated with an increased mortality risk. In DNI-patients, RW HFNO allows for advanced care without burdening ICU resources.