RT Journal Article SR Electronic T1 Post-exertion oxygen saturation as a prognostic factor for adverse outcome in patients attending the emergency department with suspected COVID-19: a substudy of the PRIEST observational cohort study JF Emergency Medicine Journal JO Emerg Med J FD BMJ Publishing Group Ltd and the British Association for Accident & Emergency Medicine SP 88 OP 93 DO 10.1136/emermed-2020-210528 VO 38 IS 2 A1 Steve Goodacre A1 Ben Thomas A1 Ellen Lee A1 Laura Sutton A1 Amanda Loban A1 Simon Waterhouse A1 Richard Simmonds A1 Katie Biggs A1 Carl Marincowitz A1 José Schutter A1 Sarah Connelly A1 Elena Sheldon A1 Jamie Hall A1 Emma Young A1 Andrew Bentley A1 Kirsty Challen A1 Chris Fitzsimmons A1 Tim Harris A1 Fiona Lecky A1 Andrew Lee A1 Ian Maconochie A1 Darren Walter YR 2021 UL http://emj.bmj.com/content/38/2/88.abstract AB Background Measurement of post-exertion oxygen saturation has been proposed to assess illness severity in suspected COVID-19 infection. We aimed to determine the accuracy of post-exertional oxygen saturation for predicting adverse outcome in suspected COVID-19.Methods We undertook a substudy of an observational cohort study across 70 emergency departments during the first wave of the COVID-19 pandemic in the UK. We collected data prospectively, using a standardised assessment form, and retrospectively, using hospital records, from patients with suspected COVID-19, and reviewed hospital records at 30 days for adverse outcome (death or receiving organ support). Patients with post-exertion oxygen saturation recorded were selected for this analysis. We constructed receiver-operating characteristic curves, calculated diagnostic parameters, and developed a multivariable model for predicting adverse outcome.Results We analysed data from 817 patients with post-exertion oxygen saturation recorded after excluding 54 in whom measurement appeared unfeasible. The c-statistic for post-exertion change in oxygen saturation was 0.589 (95% CI 0.465 to 0.713), and the positive and negative likelihood ratios of a 3% or more desaturation were, respectively, 1.78 (1.25 to 2.53) and 0.67 (0.46 to 0.98). Multivariable analysis showed that post-exertion oxygen saturation was not a significant predictor of adverse outcome when baseline clinical assessment was taken into account (p=0.368). Secondary analysis excluding patients in whom post-exertion measurement appeared inappropriate resulted in a c-statistic of 0.699 (0.581 to 0.817), likelihood ratios of 1.98 (1.26 to 3.10) and 0.61 (0.35 to 1.07), and some evidence of additional prognostic value on multivariable analysis (p=0.019).Conclusions Post-exertion oxygen saturation provides modest prognostic information in the assessment of selected patients attending the emergency department with suspected COVID-19.Trial registration number ISRCTN Registry (ISRCTN56149622) http://www.isrctn.com/ISRCTN28342533.