key: cord-1024585-k9qupfho authors: Lancet, Elizabeth A.; Gonzalez, Dario; Alexandrou, Nikolaos A.; Zabar, Benjamin; Lai, Pamela H.; Hall, Charles B.; Braun, James; Zeig‐Owens, Rachel; Isaacs, Douglas; Ben‐Eli, David; Reisman, Nathan; Kaufman, Bradley; Asaeda, Glenn; Weiden, Michael D.; Nolan, Anna; Teo, Hugo; Wei, Eric; Natsui, Shaw; Philippou, Christopher; Prezant, David J. title: Prehospital hypoxemia, measured by pulse oximetry, predicts hospital outcomes during the New York City COVID‐19 pandemic date: 2021-03-17 journal: J Am Coll Emerg Physicians Open DOI: 10.1002/emp2.12407 sha: d046cbfeac6f3a483b0702d215fe6ea9e1451997 doc_id: 1024585 cord_uid: k9qupfho OBJECTIVE: To determine if oxygen saturation (out‐of‐hospital SpO2), measured by New York City (NYC) 9‐1‐1 Emergency Medical Services (EMS), was an independent predictor of coronavirus disease 2019 (COVID‐19) in‐hospital mortality and length of stay, after controlling for the competing risk of death. If so, out‐of‐hospital SpO2 could be useful for initial triage. METHODS: A population‐based longitudinal study of adult patients transported by EMS to emergency departments (ED) between March 5 and April 30, 2020 (the NYC COVID‐19 peak period). Inclusion required EMS prehospital SpO2 measurement while breathing room air, transport to emergency department, and a positive severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) reverse transcription polymerase chain reaction test. Multivariable logistic regression modeled mortality as a function of prehospital SpO2, controlling for covariates (age, sex, race/ethnicity, and comorbidities). A competing risk model also was performed to estimate the absolute risks of out‐of‐hospital SpO2 on the cumulative incidence of being discharged from the hospital alive. RESULTS: In 1673 patients, out‐of‐hospital SpO2 and age were independent predictors of in‐hospital mortality and length of stay, after controlling for the competing risk of death. Among patients ≥66 years old, the probability of death was 26% with an out‐of‐hospital SpO2 >90% versus 54% with an out‐of‐hospital SpO2 ≤90%. Among patients <66 years old, the probability of death was 11.5% with an out‐of‐hospital SpO2 >90% versus 31% with an out‐of‐hospital SpO2 ≤ 90%. An out‐of‐hospital SpO2 level ≤90% was associated with over 50% decreased likelihood of being discharged alive, regardless of age. CONCLUSIONS: Out‐of‐hospital SpO2 and age predicted in‐hospital mortality and length of stay: An out‐of‐hospital SpO2 ≤90% strongly supports a triage decision for immediate hospital admission. For out‐of‐hospital SpO2 >90%, the decision to admit depends on multiple factors, including age, resource availability (outpatient vs inpatient), and the potential impact of new treatments. tient, was found to be an independent predictor of COVID-19 related in-hospital mortality. 10, 11 Hypoxemia is a common physiologic finding in severe COVID-19 related pneumonia, sepsis, myocardial dysfunction, or embolic disease. Oxygen saturation measured by pulse oximetry (SpO2) is inexpensive and can be obtained easily and rapidly. The primary goal of this study was to determine if oxygen saturation, measured by SpO2 in the prehospital EMS setting, was an independent predictor of COVID-19 in-hospital mortality and length of stay, in which case, out-of-hospital SpO2 could provide added accuracy to improve patient triage decisions with respect to hospitalization. This is a population-based longitudinal study using data from adult In 1673 patients, we examined the association of prehospital SpO2 obtained from the FDNY-EMS database with in-hospital mortality and length of stay, after controlling for the competing risk of death from the NYC H+H database. Mortality was coded as a binary variable (yes/no). Patients who died after being discharged from the hospital (n = 66) or those that remained hospitalized (n = 10) at the end of follow-up were considered alive in our mortality analyses. Length-of-stay was computed as the difference in the number of hours between the date and time of discharge (from inpatient unit or ED) or death, whichever came first, and the date and time of ED arrival. Patients still in the hospital at the end of follow-up were censored (n = 10). Unadjusted outcomes were compared using descriptive statistics. Continuous data (out-of-hospital SpO2, age, and hospital length of stay) were compared using medians and interquartile ranges (IQR) and The Bottom Line an FDNY-EMS out-of-hospital SpO2 and those without; however, the study cohort had a higher proportion of comorbid medical conditions than those without an out-of-hospital SpO2 (Table 1 ). Results from our multivariable model of out-of-hospital SpO2 and inhospital mortality are shown in Table 2 (Table 2) . When the analysis was stratified by age in quartiles or out-of-hospital SpO2 in 10% increments, no additional risk factors were statistically significant. We found that the positive predicted values of out-of-hospital SpO2 level on death differed significantly by age group ( Results from our competing risk model are shown in Table 4 . A limitation of our study is that it included only FDNY-EMS patients transported for subsequent ED evaluation at 11 NYC H+H acutecare hospitals. First, FDNY-EMS accounts for over 60% of all NYC 9-1-1 ambulances. 16 There is no reason to believe patients would be treated any differently by other 9-1-1 ambulance emergency medical with pulse oximetry and increased call volume may have led to missing F I G U R E 1 Cumulative incidence functions for the probability of being discharged from the hospital alive after accounting for death, by out-of-hospital SpO2 level and age. Shading represents 95% confidence intervals measurements or data entry. We also note that our mortality rates were higher than that seen in other parts of the country; however, this was expected as NYC was the early epicenter of COVID-19 in the United States and knowledge on its treatment was in its infancy. Although most patient characteristics were similar between those with and without an FDNY-EMS out-of-hospital SpO2 measurement a bias may have been introduced because those with measurement had a higher proportion of comorbid medical conditions ( We report on 1673 COVID-19 patients with out-of-hospital SpO2 measured by FDNY-EMS in the prehospital setting who were then transported to NYC H+H ED for further evaluation and possible admission. Both age and out-of-hospital SpO2 were independent predictors of in-hospital mortality and length of stay, after controlling for the competing risk of death. Among older patients ≥66 years old, the proportion who died in those with an out-of-hospital SpO2 > 90% was 26% compared to 54% in those with an out-of-hospital SpO2 ≤90%. Among younger patients ≤65 years old with an out-of-hospital SpO2 > 90%, 11.5% died compared to 31% in those with an outof-hospital SpO2 ≤90%. After controlling for the competing risk of death, patients with an out-of-hospital SpO2 level ≤90% was associated with over a 50% decreased likelihood of being discharged alive (HR, 0.48; 95% CI, 0.43-0.54; P < 0.001), regardless of age. In contrast to prior reports, 8 we did not find that race/ethnicity or medical history was significant in predicting in-hospital mortality or length of stay after controlling for the competing risk of death, but this may be lack of power because differences were found in our sensitivity analyses when including patients who did not have out-of-hospital SpO2 measured. To date, several peer-reviewed COVID-19 studies have detailed the association between commonly accepted risk factors (ie, age, race/ethnicity, comorbidities, inflammatory biomarkers) and inhospital 4-8 and out-of-hospital mortality. 3 Although all studies found increasing age to be an independent predictor of mortality, we could find only 2 studies that included out-of-hospital SpO2 in their mortality analyses. Both found that out-of-hospital SpO2, measured day 1 of hospital admission while breathing supplemental oxygen, was an independent predictor of in-hospital mortality. In the NYU study, 10 hypoxic patients (out-of-hospital SpO2 < 88% vs 92%) were twice as Triage decisions must be made. Our data inform such decisions while at the same time making a convincing argument that patients not admitted remain at risk and should be provided with close outpatient monitoring. Though we expect the association between prehospital hypoxemia and disease severity to remain a critical factor in the admission decision, the availability of new treatment options will further affect this decision. Several algorithms exist for risk-stratifying patients with community acquired bacterial pneumonias, of which the best validated are the CURB-65 Scale (Confusion, Urea, Respiratory rate, Blood pressure ,and age ≥65 years) and the Pneumonia Severity Index. 24, 25 However, there is concern that these algorithms may not be predictive for patients with COVID-19 pneumonia as they proved inaccurate in riskstratifying patients with viral pneumonia during the Influenza A (H1N1) 2009 pandemic. 26 In the EMS prehospital setting, critical laboratory data required for these algorithms are not available, even if they were validated for this infection. In contrast, age and SpO2 were simple to obtain, readily available, and proved predictive of both in-hospital mortality and length of stay after controlling for the competing risk of death. In conclusion, age and SpO2 measured in the prehospital setting predict in-hospital mortality and length of stay and improve our ability to risk-stratify COVID-19 infected patients. An out-of-hospital SpO2 ≤90% strongly supports a triage decision for immediate hospital admission, regardless of patient age. For out-of-hospital SpO2 >90%, the decision to admit depends on multiple factors including age, resource availability (outpatient vs inpatient) and the potential impact of new treatments. This study did not address alternative care situations for patients with normal out-of-hospital SpO2 values such as close remote home monitoring using telemedicine assisted by frequent outof-hospital SpO2, temperature, and symptom checks. Further research is needed to determine if age and out-of-hospital SpO2 coupled with other patient characteristics (eg, sex, race/ethnicity, medical history, symptoms, temperature, and other biomarkers) could further improve our accuracy in risk-stratifying COVID-19 infected patients in the outpatient and prehospital settings. 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The European respiratory journal Making sense of scoring systems in community acquired pneumonia Severity of influenza A 2009 (H1N1) pneumonia is underestimated by routine prediction rules. Results from a prospective, population-based study DG and NAA conceived the study and all authors designed the trial.JB and HT managed the data. EAL and CBH provided statistical advice on study design and analyzed the data; PHL and BZ chaired the data oversight committee. DG, NAA, and DJP drafted the manuscript, and all authors contributed substantially to its revision. DJP takes responsibility for the paper as a whole. The authors have no conflicts of interest to report. This research was supported by the Fire Department of the City of New York.