Bouras and colleagues attempted to use the cortisol total/CRP ratio for the prediction of hospital-acquired pneumonia (HAP) and initiation of corticosteroid therapy in patients with severe traumatic brain injury (TBI) and with adrenal insufficiency [1]. They found that a cortisol total/CRP ratio > 3 upon admission may predict the development of HAP in patients with severe TBI [1]. The study is interesting, while we have some concerns about the study design and interpretation of the data. The CORTI-TC trial [2] revealed that low-dose hydrocortisone with fludrocortisone did not improve the outcome of patients with TBI. Although the relatively small sample size is considered as a reason for negative findings, we believe that stratified analyses are more important for such a study. HAP is a form of nosocomial pneumonia, which is distinct from VAP [3]. In a published guideline from the Infectious Diseases Society of America and the American Thoracic Society, the term HAP denotes an episode of pneumonia not associated with mechanical ventilation [4, 5]. As acknowledged also by the authors, mechanical ventilation promotes a specific histological pattern of pneumonia [1]. Hence, patients with HAP and ventilator-associated pneumonia (VAP) should be categorized into two distinct groups. All cases of recorded HAP were VAP [1], which means all these patients received mechanical ventilation. Thus, we are eager to know about the patients without HAP. What is the percentage of mechanical ventilation use in these patients? In this post hoc analysis of the CORTI-TC trial, the authors may hypothesize that the cortisol total/CRP ratio may or may not predict HAP. However, HAP is more associated with disease severity per se, e.g., consciousness state, prophylactic use of antibiotics, duration of intensive care, and mechanical ventilation, with many comorbidities potentially acting as confounding factors. We are then interested to know about the prophylactic use of antibiotics in the CORTI-TC trial. Seemingly, results from Table 1 and Table 2 are conflicting [1]. Whereas in Table 1, up to 20% patients without HAP (versus 5.6% in those without HAP) had body temperature > 39.0 °C upon admission, in Table 2, multivariate analysis revealed that body temperature > 39.0 °C was closely associated with HAP [1]. Besides, the unit of the leucocyte count in Table 1 is grams per liter, which should be typographical errors. In summary, HAP is common after TBI and closely associated with its outcome. More studies are warranted to seek surrogate biomarkers to predict the occurrence of HAP.

中文翻译：

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皮质醇总量/CRP比值用于预测创伤性脑损伤患者的医院获得性肺炎和开始皮质类固醇治疗

Bouras 及其同事尝试使用皮质醇总量/CRP 比率来预测医院获得性肺炎 (HAP) 和严重创伤性脑损伤 (TBI) 和肾上腺功能不全患者的皮质类固醇治疗 [1]。他们发现，入院时皮质醇总量/CRP 比值 > 3 可以预测重度 TBI 患者发生 HAP [1]。这项研究很有趣，但我们对研究设计和数据解释有些担忧。CORTI-TC 试验 [2] 表明，低剂量氢化可的松与氟氢可的松并没有改善 TBI 患者的预后。尽管样本量相对较小被认为是负面结果的一个原因，但我们认为分层分析对于此类研究更为重要。HAP 是一种医院获得性肺炎，这与 VAP [3] 不同。在美国传染病学会和美国胸科学会发布的指南中，术语 HAP 表示与机械通气无关的肺炎发作 [4, 5]。作者也承认，机械通气促进了肺炎的特定组织学模式 [1]。因此，HAP 和呼吸机相关性肺炎 (VAP) 患者应分为两个不同的组。所有记录的 HAP 病例均为 VAP [1]，这意味着所有这些患者都接受了机械通气。因此，我们渴望了解没有 HAP 的患者。这些患者使用机械通气的百分比是多少？在 CORTI-TC 试验的这个事后分析中，作者可能假设皮质醇总量/CRP 比率可能会或可能不会预测 HAP。然而，HAP 与疾病严重程度本身更相关，例如意识状态、预防性使用抗生素、重症监护的持续时间和机械通气，许多合并症可能作为混杂因素。然后我们有兴趣了解 CORTI-TC 试验中抗生素的预防性使用。表 1 和表 2 的结果似乎是相互矛盾的 [1]。而在表 1 中，高达 20% 的无 HAP 患者（而无 HAP 的患者为 5.6%）在入院时体温 > 39.0 °C，而在表 2 中，多变量分析显示体温 > 39.0 °C 与 HAP 密切相关[1]。另外，表1中白细胞计数的单位是克/升，应该是印刷错误。总之，HAP 在 TBI 后很常见，并且与其结果密切相关。