<u>Background</u>

The variability of Covid-19 severity between patients has driven efforts to identify prognosticating laboratory markers that could aid clinical decision making. Procalcitonin (PCT) is classically used as a diagnostic marker in bacterial infections, but its role in predicting Covid-19 disease severity is emerging. We aimed to identify the association between PCT and Covid-19 disease severity in a critical care setting and whether bacterial co-infection is implicated.

<u>Methods</u>

We retrospectively reviewed Covid-19 patients with PCT levels measured in a critical care setting at our institution between February and September 2020. Laboratory markers including peak PCT values and a range of bacterial culture results were analysed. Outcomes were the requirement and duration of invasive mechanical ventilation as well as inpatient mortality.

<u>Results</u>

In total, 60 patients were included; 68% required invasive mechanical ventilation and 45% died as inpatient. Univariate analysis identified higher peak PCT levels significantly associated with both the requirement for invasive mechanical ventilation (OR: 3.2, 95% CI 1.3-9.0, p=0.02) and inpatient mortality (OR: 2.6, 95% CI 1.1-6.6, p=0.03). Higher peak PCT levels was an independent predictor of mortality on multivariate analysis (OR 3.7, 95% CI 1.1-12.4, p=0.03). There was a significant positive correlation between increased peak PCT levels and duration on invasive mechanical ventilation. No significant difference was found between peak PCT levels of patients with positive and negative bacterial cultures.

<u>Conclusions</u>

Elevated PCT levels in Covid-19 patients are associated with respiratory failure requiring prolonged invasive mechanical ventilation and inpatient mortality. This association may be independent of bacterial co-infection.

<u>背景</u>

患者之间 Covid-19 严重程度的差异促使人们努力确定可以帮助临床决策的预测性实验室标志物。降钙素原 (PCT) 通常用作细菌感染的诊断标志物，但其在预测 Covid-19 疾病严重程度方面的作用正在显现。我们旨在确定重症监护环境中 PCT 与 Covid-19 疾病严重程度之间的关联，以及是否涉及细菌合并感染。

<u>方法</u>

我们回顾性审查了 2020 年 2 月至 2020 年 9 月期间在我们机构的重症监护环境中测量 PCT 水平的 Covid-19 患者。分析了实验室标志物，包括峰值 PCT 值和一系列细菌培养结果。结果是有创机械通气的要求和持续时间以及住院死亡率。

<u>结果</u>

共纳入 60 名患者；68% 需要有创机械通气，45% 在住院期间死亡。单变量分析发现较高的峰值 PCT 水平与有创机械通气的需求（OR：3.2，95% CI 1.3-9.0，p=0.02）和住院死亡率（OR：2.6，95% CI 1.1-6.6，p= 0.03）。在多变量分析中，较高的峰值 PCT 水平是死亡率的独立预测因子（OR 3.7，95% CI 1.1-12.4，p=0.03）。PCT 峰值水平升高与有创机械通气持续时间呈显着正相关。细菌培养阳性和阴性患者的 PCT 峰值水平没有发现显着差异。

<u>结论</u>

Covid-19 患者的 PCT 水平升高与需要长时间有创机械通气的呼吸衰竭和住院死亡率有关。这种关联可能与细菌合并感染无关。