Use of the first National Early Warning Score recorded within 24 hours of admission to estimate the risk of in-hospital mortality in unplanned COVID-19 patients: a retrospective cohort study
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Abstract
Although the National Early Warning Score (NEWS) and its latest version NEWS2 are recommended for monitoring deterioration in patients admitted to hospital, little is known about their performance in COVID-19 patients. We aimed to compare the performance of the NEWS and NEWS2 in patients with COVID-19 versus those without during the first phase of the pandemic.
Design
A retrospective cross-sectional study.
Setting
Two acute hospitals (Scarborough and York) are combined into a single dataset and analysed collectively.
Participants
Adult (≥18 years) non-elective admissions discharged between 11 March 2020 and 13 June 2020 with an index or on-admission NEWS2 electronically recorded within ±24 hours of admission to predict mortality at four time points (in-hospital, 24 hours, 48 hours and 72 hours) in COVID-19 versus non-COVID-19 admissions.
Results
Out of 6480 non-elective admissions, 620 (9.6%) had a diagnosis of COVID-19. They were older (73.3 vs 67.7 years), more often male (54.7% vs 50.1%), had higher index NEWS (4 vs 2.5) and NEWS2 (4.6 vs 2.8) scores and higher in-hospital mortality (32.1% vs 5.8%). The c-statistics for predicting in-hospital mortality in COVID-19 admissions was significantly lower using NEWS (0.64 vs 0.74) or NEWS2 (0.64 vs 0.74), however, these differences reduced at 72hours (NEWS: 0.75 vs 0.81; NEWS2: 0.71 vs 0.81), 48 hours (NEWS: 0.78 vs 0.81; NEWS2: 0.76 vs 0.82) and 24hours (NEWS: 0.84 vs 0.84; NEWS2: 0.86 vs 0.84). Increasing NEWS2 values reflected increased mortality, but for any given value the absolute risk was on average 24% higher (eg, NEWS2=5: 36% vs 9%).
Conclusions
The index or on-admission NEWS and NEWS2 offers lower discrimination for COVID-19 admissions versus non-COVID-19 admissions. The index NEWS2 was not proven to be better than the index NEWS. For each value of the index NEWS/NEWS2, COVID-19 admissions had a substantially higher risk of mortality than non-COVID-19 admissions which reflects the increased baseline mortality risk of COVID-19.
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SciScore for 10.1101/2020.07.13.20144907: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization We determined the discrimination of NEWS and NEWS2 using the concordance or c-statistic which is interpreted as the probability that a deceased patient has a higher risk of death than a randomly chosen non-deceased patient. Blinding not detected. Power Analysis not detected. Sex as a biological variable For each emergency admission, we obtained a pseudonymised patient identifier, patient’s age (years), gender (male/female), ethnicity, body mass index (BMI kg/m2), discharge status (alive/dead), admission and discharge date and time, diagnoses codes based on the 10th revision of the International Statistical Classification of Diseases … SciScore for 10.1101/2020.07.13.20144907: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization We determined the discrimination of NEWS and NEWS2 using the concordance or c-statistic which is interpreted as the probability that a deceased patient has a higher risk of death than a randomly chosen non-deceased patient. Blinding not detected. Power Analysis not detected. Sex as a biological variable For each emergency admission, we obtained a pseudonymised patient identifier, patient’s age (years), gender (male/female), ethnicity, body mass index (BMI kg/m2), discharge status (alive/dead), admission and discharge date and time, diagnoses codes based on the 10th revision of the International Statistical Classification of Diseases (ICD-10) [9] [10], NEWS2 (including its subcomponents respiratory rate, temperature, systolic pressure, pulse rate, oxygen saturation, oxygen supplementation, oxygen scales 1 & 2, and alertness including confusion) [4,5]. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:There are several limitations to our study. (1) This study data is from a single NHS Trust and the extent to which these findings are generalisable, especially to minority ethnic groups with higher COVID-19 mortality, needs further study. (2) We used the index NEWS2 which reflects the ‘on-admission’ risk of mortality of the patients. Nonetheless, NEWS2 is repeatedly updated for each patient according to local hospital protocols, and the extent to which changes in NEWS2 over time reflect changes in mortality risk needs further study. (3) Although we found no evidence of NEWS2 as having a superior performance to NEWS, it is important to note that our index NEWS data are hypothetical in the sense that the Trust has been using NEWS2 since April 2019. Nevertheless, it is worth noting that a recent, albeit small Italian study based on 71 hospitalised COVID-19 patients found NEWS2 to be a good predictor (with a high c-statistic 0.90) of subsequent ICU admission for COVID-19 patients but was not able to consider mortality because of insufficient events [6]. Our study did not consider ICU admissions as an outcome because the number of ICU admissions were low but Kostakis et al [7] used it as a composite outcome with in-hospital mortality (5).
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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