In critically ill immunocompromised patients with acute respiratory failure (ARF), the mortality rate did not differ between HFNO alone and non-invasive ventilation (NIV) alternating with high-flow nasal oxygen (HFNO). However, study power was limited, so results should be interpreted with caution.

Between Jan 21, 2017 to March 4, 2019, of 497 eligible patients, 300 were randomly assigned but one patient withdrew consent, leaving 299 patients included in the intention-to-treat analysis (154 assigned to the HFNO alone group and 145 assigned to NIV group).

Mortality rate at day 28 was 36% (95% CI 29·2 to 44·2; 56 of 154 patients) in the HFNO alone group and 35% (27·9 to 43·2; 51 of 145 patients) in the NIV group (absolute difference 1·2% [95% CI −9·6 to 11·9]; p=0·83).

None of the other prespecified secondary outcomes were different between groups except for greater decreased discomfort after initiation of HFNO than with NIV (−4 mm on visual analogic scale [IQR −18 to 4] vs 0 mm [–16 to 17]; p=0·040).

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