Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). This is a multinational, multicentre, prospective cohort study embedded in the ISARIC-WHO COVID-19 Clinical Characterisation Protocol. Patients with laboratory-confirmed SARS-CoV-2 infection who required hospital admission were recruited prospectively. Patients treated with HFNC, NIV, or IMV within the first 24 h of hospital admission were included in this study. Descriptive statistics, random forest, and logistic regression analyses were used to describe clinical characteristics and compare clinical outcomes among patients treated with the different types of advanced respiratory support. A total of 66,565 patients were included in this study. Overall, 82.6% of patients were treated in HIC, and 40.6% were admitted to the hospital during the first pandemic wave. During the first 24 h after hospital admission, patients in HICs were more frequently treated with HFNC (48.0%), followed by NIV (38.6%) and IMV (13.4%). In contrast, patients admitted in lower- and middle-income countries (LMICs) were less frequently treated with HFNC (16.1%) and the majority received IMV (59.1%). The failure rate of non-invasive respiratory support (i.e. HFNC or NIV) was 15.5%, of which 71.2% were from HIC and 28.8% from LMIC. The variables most strongly associated with non-invasive ventilation failure, defined as progression to IMV, were high leukocyte counts at hospital admission (OR [95%CI]; 5.86 [4.83–7.10]), treatment in an LMIC (OR [95%CI]; 2.04 [1.97–2.11]), and tachypnoea at hospital admission (OR [95%CI]; 1.16 [1.14–1.18]). Patients who failed HFNC/NIV had a higher 28-day fatality ratio (OR [95%CI]; 1.27 [1.25–1.30]). In the present international cohort, the most frequently used advanced respiratory support was the HFNC. However, IMV was used more often in LMIC. Higher leucocyte count, tachypnoea, and treatment in LMIC were risk factors for HFNC/NIV failure. HFNC/NIV failure was related to worse clinical outcomes, such as 28-day mortality. Trial registration This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable.

中文翻译：

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国际严重急性呼吸系统疾病和新发感染 (ISARIC) COVID-19 研究中重症 COVID-19 患者的呼吸支持：一项前瞻性、多国、观察性研究

高达 30% 的 COVID-19 住院患者需要高级呼吸支持，包括高流量鼻插管 (HFNC)、无创机械通气 (NIV) 或有创机械通气 (IMV)。我们的目的是描述高收入国家 (HIC) 和中低收入国家在大流行的头两年期间接受重症 COVID-19 治疗的患者无创呼吸支持失败的临床特征、结果和风险因素 (中低收入国家）。这是一项包含在 ISARIC-WHO COVID-19 临床表征方案中的多国、多中心、前瞻性队列研究。前瞻性招募了需要住院的经实验室确诊的 SARS-CoV-2 感染患者。本研究包括入院后 24 小时内接受 HFNC、NIV 或 IMV 治疗的患者。使用描述性统计、随机森林和逻辑回归分析来描述临床特征并比较接受不同类型高级呼吸支持治疗的患者的临床结果。本研究共纳入 66,565 名患者。总体而言，82.6% 的患者在 HIC 接受治疗，40.6% 的患者在第一波大流行期间入院。在入院后的前 24 小时内，HICs 患者更频繁地接受 HFNC (48.0%) 治疗，其次是 NIV (38.6%) 和 IMV (13.4%)。相比之下，在低收入和中等收入国家 (LMIC) 收治的患者接受 HFNC 治疗的频率较低 (16.1%)，大多数患者接受 IMV (59.1%)。无创呼吸支持（即HFNC或NIV）的失败率为15.5%，其中71.2%来自HIC，28.8%来自LMIC。与无创通气失败（定义为进展为 IMV）最密切相关的变量是入院时的高白细胞计数（OR [95%CI]；5.86 [4.83–7.10]）、在 LMIC 中的治疗（OR [95% CI]；2.04 [1.97–2.11]）和入院时呼吸急促（OR [95%CI]；1.16 [1.14–1.18]）。HFNC/NIV 失败的患者具有更高的 28 天死亡率（OR [95%CI]；1.27 [1.25–1.30]）。在目前的国际队列中，最常用的高级呼吸支持是 HFNC。然而，IMV 在 LMIC 中使用得更多。LMIC 中较高的白细胞计数、呼吸急促和治疗是 HFNC/NIV 失败的危险因素。HFNC/NIV 失败与较差的临床结果相关，例如 28 天死亡率。试验注册 这是一项前瞻性观察研究；所以，