Objectives The National Early Warning Score 2 (NEWS2) is validated for predicting acute deterioration, however, the binary grading of inspired oxygen fraction (FiO2) may limit performance. We evaluated the incorporation of FiO2 as a weighted categorical variable on NEWS2 prediction of patient deterioration. Setting Two hospitals at a single medical centre, Guy’s and St Thomas’ NHS Foundation Trust. Design Retrospective cohort of all ward admissions, with a viral respiratory infection (SARS-CoV-2/influenza). Participants 3704 adult ward admissions were analysed between 01 January 2017 and 31 December 2021. Methods The NEWS-FiO2 score transformed FiO2 into a weighted categorical variable, from 0 to 3 points, substituting the original 0/2 points. The primary outcome was a composite of cardiac arrest, unplanned critical care admission or death within 24 hours of the observation. Sensitivity, positive predictive value (PPV), number needed to evaluate (NNE) and area under the receiver operating characteristic curve (AUROC) were calculated. Failure analysis for the time from trigger to outcome was compared by log-rank test. Results The mean age was 60.4±19.4 years, 52.6% were men, with a median Charlson Comorbidity of 0 (IQR 3). The primary outcome occurred in 493 (13.3%) patients, and the weighted FiO2 score was strongly associated with the outcome (p=<0.001). In patients receiving supplemental oxygen, 78.5% of scores were reclassified correctly and the AUROC was 0.81 (95% CI 0.81 to 0.81) for NEWS-FiO2 versus 0.77 (95% CI 0.77 to 0.77) for NEWS2. This improvement persisted in the whole cohort with a significantly higher failure rate for NEWS-FiO2 (p=<0.001). At the 5-point threshold, the PPV increased by 22.0% (NNE 6.7) for only a 3.9% decrease in sensitivity. Conclusion Transforming FiO2 into a weighted categorical variable improved NEWS2 prediction for patient deterioration, significantly improving the PPV. Prospective external validation is required before institutional implementation. Data are available upon reasonable request.

中文翻译：

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通过添加吸入氧分数作为加权变量，提高了国家早期预警评分 2 对病毒性呼吸道疾病住院患者的预测价值

目标 国家早期预警评分 2 (NEWS2) 经验证可预测急性恶化，但吸入氧分数 (FiO2) 的二元分级可能会限制性能。我们评估了将 FiO2 作为加权分类变量纳入 NEWS2 预测患者病情恶化的情况。将两家医院设置在一个医疗中心：盖伊医院和圣托马斯国民保健服务基金会信托基金。设计所有入院病房的病毒性呼吸道感染（SARS-CoV-2/流感）的回顾性队列。对2017年1月1日至2021年12月31日期间入院的3704名成人病房的参与者进行了分析。方法NEWS-FiO2评分将FiO2转化为加权分类变量，从0分到3分，代替原来的0/2分。主要结局是心脏骤停、计划外重症监护入院或观察后 24 小时内死亡的综合结果。计算灵敏度、阳性预测值（PPV）、需要评估的数量（NNE）和受试者工作特征曲线下面积（AUROC）。通过对数秩检验比较从触发到结果的时间的故障分析。结果 平均年龄为 60.4±19.4 岁，52.6% 为男性，查尔森合并症中位数为 0 (IQR 3)。主要结果发生在 493 名 (13.3%) 患者中，加权 FiO2 评分与结果密切相关 (p=<0.001)。在接受吸氧的患者中，78.5% 的评分被正确重新分类，NEWS-FiO2 的 AUROC 为 0.81（95% CI 0.81 至 0.81），而 NEWS2 的 AUROC 为 0.77（95% CI 0.77 至 0.77）。这种改善在整个队列中持续存在，NEWS-FiO2 的失败率显着较高（p=<0.001）。在 5 点阈值处，PPV 增加了 22.0% (NNE 6.7)，而灵敏度仅下降了 3.9%。结论 将 FiO2 转换为加权分类变量可以改善 NEWS2 对患者病情恶化的预测，从而显着改善 PPV。在制度实施之前需要进行前瞻性的外部验证。数据可根据合理要求提供。