Background

Clinicians, afraid of missing intracranial injuries, liberally obtain computed tomographic (CT) head imaging in blunt trauma patients. Prior work suggests that clinical criteria (National Emergency X-Radiography Utilization Study [NEXUS] Head CT decision instrument [DI]) can reliably identify patients with important injuries, while excluding injury, and the need for imaging in many patients. Validating this DI requires confirmation of the hypothesis that the lower 95% confidence limit for its sensitivity in detecting serious injury exceeds 99.0%.

A secondary goal of the study was to complete an independent validation and comparison of the Canadian and NEXUS Head CT rules among the subgroup of patients meeting the inclusion and exclusion criteria.

Methods and findings

We conducted a prospective observational study of the NEXUS Head CT DI in 4 hospital emergency departments between April 2006 and December 2015. Implementation of the rule requires that patients satisfy 8 criteria to achieve “low-risk” classification. Patients are excluded from “low-risk” classification and assigned “high-risk” status if they fail to meet 1 or more criteria. We examined the instrument’s performance in assigning “high-risk” status to patients requiring neurosurgical intervention among a cohort of 11,770 blunt head injury patients.

The NEXUS Head CT DI assigned high-risk status to 420 of 420 patients requiring neurosurgical intervention (sensitivity, 100.0% [95% confidence interval [CI]: 99.1%–100.0%]). The instrument assigned low-risk status to 2,823 of 11,350 patients who did not require neurosurgical intervention (specificity, 24.9% [95% CI: 24.1%–25.7%]). None of the 2,823 low-risk patients required neurosurgical intervention (negative predictive value [NPV], 100.0% [95% CI: 99.9%–100.0%]).

The DI assigned high-risk status to 759 of 767 patients with significant intracranial injuries (sensitivity, 99.0% [95% CI: 98.0%–99.6%]). The instrument assigned low-risk status to 2,815 of 11,003 patients who did not have significant injuries (specificity, 25.6% [95% CI: 24.8%–26.4%]). Significant injuries were absent in 2,815 of the 2,823 patients assigned low-risk status (NPV, 99.7% [95% CI: 99.4%–99.9%]).

Of our patients, 7,759 (65.9%) met the inclusion and exclusion criteria of the Canadian Head CT rule, including 111 patients (1.43%) who required neurosurgical intervention and 306 (3.94%) who had significant intracranial injuries. In our study, the Canadian criteria for neurosurgical intervention identified 108 of 111 patients requiring neurosurgical intervention to yield a sensitivity of 97.3% (95% CI: 92.3%–99.4%) and exhibited a specificity of 58.8% (95% CI: 57.7%–59.9%). The NEXUS rule, when applied to this same cohort, identified all 111 patients requiring neurosurgical intervention, yielding a sensitivity of 100% (95% CI: 96.7%–100.0%) with a specificity of 32.6% (95% CI: 31.5%–33.6%). Our study found that the Canadian medium-risk factors identified 301 of 306 patients with significant injuries (sensitivity = 98.4%; 95% CI: 96.2%–99.5%), while the NEXUS rule identified 299 of these patients (sensitivity = 97.7%; 95% CI: 95.3%–99.1%). In our study, the Canadian medium-risk rule exhibited a specificity of 12.3% (95% CI: 11.6%–13.1%), while the NEXUS rule exhibited a specificity of 33.3% (95% CI: 32.3%–34.4%).

Limitations of the study may arise from application of the rule by different clinicians in different environments. Clinicians may vary in their interpretation and application of the instrument’s criteria and risk assignment and may also vary in deciding which patients require intervention. The instrument’s specificity is also subject to spectrum bias and may change with variations in the proportion of “low-risk” patients seen in other centers.

Conclusions

The NEXUS Head CT DI reliably identifies blunt trauma patients who require head CT imaging and could significantly reduce the use of CT imaging.

中文翻译：

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验证国家急诊X射线照相术研究（NEXUS）头部计算机断层摄影（CT）决策工具对钝性颅脑损伤患者进行选择性成像的敏感性：一项观察性研究

背景

临床医生害怕遗漏颅内损伤，因此在钝性创伤患者中广泛获得了计算机断层扫描（CT）头部成像。先前的工作表明，临床标准（美国国家紧急X射线照相应用研究[NEXUS] Head CT决策仪[DI]）可以可靠地识别出重伤患者，而排除了受伤情况，并且许多患者都需要成像。验证此DI要求确认以下假设：较低的95％置信极限对其检测严重伤害的敏感性超过99.0％。

该研究的第二个目标是完成对符合纳入和排除标准的患者亚组中加拿大和NEXUS Head CT规则的独立验证和比较。

方法和发现

我们于2006年4月至2015年12月在4个医院急诊科中对NEXUS Head CT DI进行了前瞻性观察研究。该规则的实施要求患者满足8个标准以实现“低风险”分类。如果患者不符合1个或多个标准，则将其从“低风险”分类中排除，并分配为“高风险”状态。我们检查了该仪器在11770名钝性颅脑损伤患者中为需要神经外科干预的患者分配“高危”状态的性能。

NEXUS Head CT DI将420例需要神经外科干预的患者中的420例归为高危患者（敏感性为100.0％[95％置信区间[CI]：99.1％–100.0％]）。该仪器为不需要神经外科干预的11,350例患者中的2,823例分配了低风险状态（特异性为24.9％[95％CI：24.1％–25.7％]）。2,823名低危患者中没有一个需要进行神经外科手术（负预测值[NPV]，100.0％[95％CI：99.9％–100.0％]）。

DI对767例严重颅内损伤患者中的759例分配了高危状态（敏感性为99.0％[95％CI：98.0％–99.6％]）。该仪器将11,003名未受到重大伤害的患者中的2,815名分配为低风险状态（特异性为25.6％[95％CI：24.8％–26.4％]）。在低风险状态的2,823名患者中，有2,815名没有严重受伤（NPV，99.7％[95％CI：99.4％–99.9％]）。

在我们的患者中，有7759名（65.9％）符合加拿大头部CT规则的纳入和排除标准，包括111名需要神经外科手术的患者（1.43％）和306名（3.94％）严重颅内损伤的患者。在我们的研究中，加拿大的神经外科干预标准确定了111例需要神经外科干预的患者，其中108例的敏感性为97.3％（95％CI：92.3％–99.4％），特异性为58.8％（95％CI：57.7％）。 –59.9％）。NEXUS规则应用于同一队列时，可以识别出所有111名需要神经外科干预的患者，其敏感性为100％（95％CI：96.7％–100.0％），特异性为32.6％（95％CI：31.5％– 33.6％）。我们的研究发现，在306例严重受伤的患者中，加拿大的中危因素确定了301例（敏感性= 98.4％； 95％CI：96.2％–99.5％），而NEXUS规则确定了299例患者（敏感性= 97.7％； 95％CI：95.3％–99.1％）。在我们的研究中，加拿大中等风险规则的特异性为12.3％（95％CI：11.6％–13.1％），而NEXUS规则的特异性为33.3％（95％CI：32.3％–34.4％）。

该研究的局限性可能是由于不同临床医生在不同环境中应用该规则而引起的。临床医生对仪器标准和风险分配的解释和应用可能有所不同，在决定需要干预的患者方面也可能有所不同。该仪器的特异性也会受到频谱偏差的影响，并且可能会随其他中心的“低风险”患者比例的变化而变化。

结论

NEXUS头颅CT DI能够可靠地识别需要头颅CT成像的钝性创伤患者，并且可以显着减少CT成像的使用。