Evaluation of pragmatic oxygenation measurement as a proxy for Covid-19 severity

Maaike C. Swets, Steven Kerr, James Scott-Brown, Adam Brown, Rishi K Gupta, Jonathan Millar, Enti Spata, Fiona McCurrach, Andrew D Bretherick, Annemarie B Docherty, David Harrison, Kathy Rowan, Neil Young, Geert H Groeneveld, Jake Dunning, Jonathan S. Nguyen-Van-Tam, Peter Openshaw, Peter Horby, Ewen M Harrison, Natalie StaplinMalcolm G Semple, Nazir I Lone, J Kenneth Baillie

Research output: Contribution to journal β€Ί Article β€Ί peer-review

Abstract / Description of output

Choosing optimal outcome measures maximizes statistical power, accelerates discovery and improves reliability in early-phase trials. We devised and evaluated a modification to a pragmatic measure of oxygenation function, the 𝑆/𝐹 ratio.
Because of the ceiling effect in oxyhaemoglobin saturation, 𝑆/𝐹 ratio ceases to reflect pulmonary oxygenation function at high 𝑆𝑝𝑂2 values. We found that the correlation of 𝑆/𝐹 with the reference standard (π‘ƒπ‘Žπ‘‚2/𝐹𝐼𝑂2 ratio) improves substantially when excluding 𝑆𝑝𝑂2 > 0.94 and refer to this measure as 𝑆/𝐹94.
Using observational data from 39,765 hospitalised COVID-19 patients, we demonstrate that 𝑆/𝐹94 isn predictive of mortality, and compare the sample sizes required for trials using four different outcome measures. We show that a significant difference in outcome could be detected with the smallest sample
size using 𝑆/𝐹94.
We demonstrate that 𝑆/𝐹94 is an effective intermediate outcome measure in COVID-19. It is a noninvasive measurement, representative of disease severity and provides greater statistical power.
Original languageEnglish
Article number7374
Pages (from-to)1-10
Number of pages10
JournalNature Communications
Issue number1
Early online date15 Nov 2023
Publication statusPublished - 15 Nov 2023


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