Objective assessment of the severity of pectus excavatum (PE) mainly depends on internal imaging examination, which poses radiation exposure risks and high financial costs. Our study explores the feasibility of caliper-based external measurements of the body surface to assess PE severity.

Patients with PE aged 4–18 years who underwent both internal imaging examinations and external measurements were chosen for the study. Overall, 176 patients underwent surgery and 21 underwent regular observation. The Haller index (HI) and correction index (CI) were used to derive the external measurement indices, HI-caliper and CI-caliper. Receiver-operator characteristic analysis provided the optimal cut-off values and compared the diagnostic values of HI-caliper and CI-caliper. Spearman's correlation coefficient and Cohen's kappa coefficient were used to analyze the correlation and consistency between HI-caliper or CI-caliper and HI-CT or CI-CT, respectively. Also, a paired samples t-test was used to compare the differences of HI-caliper or CI-caliper before and after surgery.

HI-caliper and CI-caliper measurements had strong correlations with HI-CT and CI-CT results (rs = 0.70, p < 0.001; rs = 0.69, p < 0.001), respectively. The optimal cut-off values of HI-caliper and CI-caliper were 1.83 (sensitivity = 0.841, specificity = 0.905) and 12% (sensitivity = 0.881, specificity = 0.857), exhibiting comparable diagnostic values with HI-CT and CI-CT. HI-caliper > 1.83 or CI-caliper > 12% had medium intensity consistency with HI-CT ≥ 3.25 or CI-CT ≥ 28% (k = 0.545, 95% confidence interval: 0.374–0.716, p < 0.001). The HI-caliper and CI-caliper values were significantly different before and after surgery.

Caliper-based external measurement is a feasible method to screen patients who require surgical intervention and for monitoring the progression of PE severity.

漏斗胸（PE）严重程度的客观评估主要依靠内部影像学检查，存在辐射暴露风险和高昂的财务成本。我们的研究探讨了基于卡尺的体表外部测量来评估 PE 严重程度的可行性。

选择接受内部成像检查和外部测量的 4-18 岁 PE 患者进行研究。总体而言，176 名患者接受了手术，21 名患者接受了定期观察。Haller 指数 (HI) 和校正指数 (CI) 用于推导外部测量指标 HI-caliper 和 CI-caliper。接受者-操作者特征分析提供了最佳截止值，并比较了 HI-caliper 和 CI-caliper 的诊断值。分别采用Spearman相关系数和Cohen's kappa系数分析HI-caliper或CI-caliper与HI-CT或C​​I-CT的相关性和一致性。此外，成对样本吨-test用于比较手术前后HI-caliper或CI-caliper的差异。

HI-caliper 和 CI-caliper 测量与 HI-CT 和 CI-CT 结果有很强的相关性（rs = 0.70，p< 0.001; rs = 0.69，p< 0.001)，分别。HI-caliper 和 CI-caliper 的最佳截止值为 1.83（敏感性 = 0.841，特异性 = 0.905）和 12%（敏感性 = 0.881，特异性 = 0.857），显示出与 HI-CT 和 CI-CT 相当的诊断值. HI-caliper > 1.83 或 CI-caliper > 12% 与 HI-CT ≥ 3.25 或 CI-CT ≥ 28% 具有中等强度一致性（ķ= 0.545, 95% 置信区间：0.374–0.716,p< 0.001)。手术前后HI-caliper和CI-caliper值有显着差异。

基于卡尺的外部测量是筛选需要手术干预的患者和监测 PE 严重程度进展的可行方法。