The Association Between Neurologic Pupillary Index (NPi) and Functional Outcomes in Critically Ill Children

The neurologic pupillary index (NPi) is an objective measurement of pupillary reactivity which may play a role in prognostication after critical illness. We hypothesized the minimum measured NPi in critically ill children would correlate with unfavorable outcomes (UO) at hospital discharge. In this single-center retrospective observational cohort study, the minimum NPi (NPimin) was compared with outcome. Unfavorable outcome was defined by death or a change in functional status scale (FSS) score of > 3 points from baseline to hospital discharge. Additionally, UO was further sub-classified into categories of severe disability (SD), defined as total discharge composite FSS of > 16 points or death and no severe disability (NSO), survivors with discharge FSS < 16. Data were extracted from one-hundred and six patients, 77 (72.6%) of whom had a primary neurologic diagnosis and 25.5% of whom died. As expected, NPimin was significantly lower in children who experienced an unfavorable outcome compared to those with a favorable outcome (0.8 versus 3.7; p< 0.001). Prognostic performance of NPimin for UO was assessed using logistic regression which demonstrated an area under the receiver operative curve (AUROC) of 0.82 and optimal NPi threshold of < 2.1. Models for SO and death performed similarly. We concluded that NPi is a clinical biomarker which may enhance future pediatric-specific prognostic models.神经瞳孔指数（neurologic pupillary index, NPi）是一种评估瞳孔反应性的客观指标，其在危重症患者的预后评估中可能具有潜在应用价值。本研究提出假说：危重症儿童的最低测量NPi值（NPimin）将与出院时的不良预后（unfavorable outcomes, UO）存在相关性。本项单中心回顾性观察队列研究旨在对比最低NPi值与患者临床结局的关联。不良预后的定义为：患者死亡，或至出院时功能状态量表（functional status scale, FSS）评分较基线水平变化超过3分。此外，我们将不良预后进一步细分为两个亚类：重度残疾（severe disability, SD），即出院时综合FSS评分＞16分或合并死亡；以及非重度残疾（no severe disability, NSO），即存活且出院时FSS评分＜16分。本研究共纳入106例患者，其中77例（72.6%）存在原发性神经系统疾病，25.5%的患者最终死亡。正如预期，出现不良预后的儿童其NPimin值显著低于预后良好的儿童（0.8 vs 3.7；p＜0.001）。我们采用logistic回归评估NPimin对不良预后的预测性能，结果显示其受试者工作特征曲线（receiver operative curve, AUROC）下面积为0.82，最佳NPi阈值为＜2.1。针对良好预后及死亡的预测模型性能与之相近。本研究最终得出结论：NPi是一种临床生物标志物，有望在未来的儿童特异性预后模型中发挥辅助作用。