ROX Index for Severity Tracking and Adverse outcomes in Respiratory patients in the Emergency Department (ROXSTAR-ED)

Peter Curtis, Adriaan Venter, Michael Davoren, Syeda Begum

Site: Wagga Wagga Base Hospital                                          Duration: 6 months prospective study

Background:

Site: Wagga Wagga Base Hospital                                          Duration: 6 months prospective study

The ROX index was devised in 2016 as a tool to predict failure of HFNPs in patients with CAP who would go on to require intubation[1]. The ROX score is a simple bedside calculation using non-invasive variables which is defined as the ratio of oxygen saturation measured by pulse oximetry (SpO2)/FiO2 to respiratory rate (RR) [2].  It was subsequently validated in a multicenter cohort study which demonstrated that a ROX >=4.88 was associated with lower risk of progressing to intubation[2]. The ROX index has been demonstrated to be valid for assessing failure of HFNPs in a non-ICU setting[3], and in predicting mortality in patients with acute hypoxic respiratory failure[4]. Its scope as a predictive tool has since expanded due to its utility as a simple non-invasive bedside tool especially during the Covid-19 pandemic to assess patients at triage and predict outcomes[3,5–9]. A large Dutch retrospective observational study with a quarter-million patients found the ROX to be more accurate than the NEWS2 at predicting 24-hour mortality in ED patients regardless of their reason for presentation[10].

Project Aims:

We aim to ascertain if serial ROX calculations can predict worse outcomes in individuals presenting to the emergency department with suspicion for respiratory pathology defined as a presenting complaint of shortness of breath/cough. Our hypothesis is a downwards trend in the ROX score will be able to identify the patients admitted to hospital with pneumonia/respiratory pathology who proceed to have negative outcomes in hospital.

Progress:

A research protocol has been constructed and is undergoing final editing. The study will be run over 6 months with data analysis and publication to follow.

References:

• 1.            Roca O, Messika J, Caralt B, García-de-Acilu M, Sztrymf B, Ricard JD, et al. Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index. J Crit Care 2016;35:200–5.
• 2.            Roca O, Caralt B, Messika J, Samper M, Sztrymf B, Hernández G, et al. An Index Combining Respiratory Rate and Oxygenation to Predict Outcome of Nasal High-Flow Therapy. Am J Respir Crit Care Med 2019;199(11):1368–76.
• 3.            Vega ML, Dongilli R, Olaizola G, Colaianni N, Sayat MC, Pisani L, et al. COVID-19 Pneumonia and ROX index: Time to set a new threshold for patients admitted outside the ICU. Pulmonology 2022;28(1):13–7.
• 4.            Liu K, Ma XY, Xiao H, Gu WJ, Lyu J, Yin HY. Association between the ROX index and mortality in patients with acute hypoxemic respiratory failure: a retrospective cohort study. Respir Res 2024;25(1):143.
• 5.            Singh R, Goswami G, Mathur T, Sirohiya P, Kumar B, Ratre BK. ROX index: A non-invasive tool in monitoring and guiding oxygen therapy in critically ill patients-A narrative review. Trends Anaesth Crit Care 2022;47:15–9.
• 6.            Gianstefani A, Farina G, Salvatore V, Alvau F, Artesiani ML, Bonfatti S, et al. Role of ROX index in the first assessment of COVID-19 patients in the emergency department. Intern Emerg Med 2021;16(7):1959–65.
• 7.            Zarama V, Quintero JA, Barbosa MM, Rodriguez S, Angel AM, Muñoz AM, et al. NEWS2, S/F-ratio and ROX-index at emergency department for the prediction of adverse outcomes in COVID-19 patients: An external validation study. Am J Emerg Med 2024;83:101–8.
• 8.            Mukhtar A, Rady A, Hasanin A, Lotfy A, El Adawy A, Hussein A, et al. Admission SpO2 and ROX index predict outcome in patients with COVID-19. Am J Emerg Med 2021;50:106–10.
• 9.            Yang S, Zhang Y, He Y, Liu S. Comparison of Prognostic Scores for Patients with COVID-19 Presenting with Dyspnea in the Emergency Department. J Emerg Med 2023;65(6):e487–94.
• 10.         Candel BGJ, de Groot B, Nissen SK, Thijssen WAMH, Lameijer H, Kellett J. The prediction of 24-h mortality by the respiratory rate and oxygenation index compared with National Early Warning Score in emergency department patients: an observational study. Eur J Emerg Med 2023;30(2):110.