Background:Abdominal aortic aneurysm (AAA) can occur in patients who are ineligible for routine ultrasound screening. A simple AAA risk score was derived and compared with current guidelines used for ultrasound screening of AAA.Methods:United Kingdom Biobank participants without previous AAA were split into a derivation cohort (n=401 820, 54.6% women, mean age 56.4 years, 95.5% White race) and validation cohort (n=83 816). Incident AAA was defined as first hospital inpatient diagnosis of AAA, death from AAA, or an AAA-related surgical procedure. A multivariable Cox model was developed in the derivation cohort into an AAA risk score that did not require blood biomarkers. To illustrate the sensitivity and specificity of the risk score for AAA, a theoretical threshold to refer patients for ultrasound at 0.25% 10-year risk was modeled. Discrimination of the risk score was compared with a model of US Preventive Services Task Force (USPSTF) AAA screening guidelines.Results:In the derivation cohort, there were 1570 (0.40%) cases of AAA over a median 11.3 years of follow-up. Components of the AAA risk score were age (stratified by smoking status), weight (stratified by smoking status), antihypertensive and cholesterol-lowering medication use, height, diastolic blood pressure, baseline cardiovascular disease, and diabetes. In the validation cohort, over 10 years of follow-up, the C-index for the model of the USPSTF guidelines was 0.705 (95% CI, 0.678–0.733). The C-index of the risk score as a continuous variable was 0.856 (95% CI, 0.837–0.878). In the validation cohort, the USPSTF model yielded sensitivity 63.9% and specificity 71.3%. At the 0.25% 10-year risk threshold, the risk score yielded sensitivity 82.1% and specificity 70.7% while also improving the net reclassification index compared with the USPSTF model +0.176 (95% CI, 0.120–0.232). A combined model, whereby risk scoring was combined with the USPSTF model, also improved prediction compared with USPSTF alone (net reclassification index +0.101 [95% CI, 0.055–0.147]).Conclusions:In an asymptomatic general population, a risk score based on patient age, height, weight, and medical history may improve identification of asymptomatic patients at risk for clinical events from AAA. Further development and validation of risk scores to detect asymptomatic AAA are needed.

中文翻译：

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症状性腹主动脉瘤 10 年风险评分的推导和验证：近 500 000 人的队列研究

背景：腹主动脉瘤 (AAA) 可能发生在不符合常规超声筛查条件的患者中。得出一个简单的 AAA 风险评分，并与当前用于 AAA 超声筛查的指南进行比较。方法：将之前没有 AAA 的英国生物库参与者分成一个推导队列（n=401 820，54.6% 为女性，平均年龄 56.4 岁，95.5 岁） % 白种人）和验证队列（n=83 816）。事件 AAA 被定义为 AAA 的首次医院住院诊断、AAA 死亡或 AAA 相关外科手术。在推导队列中将多变量 Cox 模型开发为不需要血液生物标志物的 AAA 风险评分。为了说明 AAA 风险评分的敏感性和特异性，我们建立了一个理论阈值，将 10 年风险为 0.25% 的患者转诊为超声检查。将风险评分的区分与美国预防服务工作组 (USPSTF) AAA 筛查指南的模型进行比较。结果：在推导队列中，在中位 11.3 年的随访中，有 1570 例 (0.40%) AAA 病例。AAA 风险评分的组成部分是年龄（按吸烟状况分层）、体重（按吸烟状况分层）、抗高血压和降胆固醇药物的使用、身高、舒张压、基线心血管疾病和糖尿病。在验证队列中，经过 10 年以上的随访，USPSTF 指南模型的 C 指数为 0.705（95% CI，0.678–0.733）。作为连续变量的风险评分的 C 指数为 0.856（95% CI，0.837–0.878）。在验证队列中，USPSTF 模型的敏感性为 63.9%，特异性为 71.3%。在 0.25% 的 10 年期风险阈值下，与 USPSTF 模型相比，风险评分产生了 82.1% 的敏感性和 70.7% 的特异性，同时还改善了净重分类指数 +0.176（95% CI，0.120–0.232）。与单独的 USPSTF 相比，风险评分与 USPSTF 模型相结合的组合模型也改善了预测（净重新分类指数 +0.101 [95% CI，0.055-0.147]）。结论：在无症状的一般人群中，基于风险评分的风险评分对患者年龄、身高、体重和病史的分析可能会提高对处于 AAA 临床事件风险中的无症状患者的识别。需要进一步开发和验证风险评分以检测无症状的 AAA。由此风险评分与 USPSTF 模型相结合，与单独的 USPSTF 相比也改善了预测（净重新分类指数 +0.101 [95% CI，0.055–0.147]）。结论：在无症状的一般人群中，基于患者年龄的风险评分，身高、体重和病史可能会改善无症状患者的识别，这些患者有 AAA 临床事件的风险。需要进一步开发和验证风险评分以检测无症状的 AAA。由此风险评分与 USPSTF 模型相结合，与单独的 USPSTF 相比也改善了预测（净重新分类指数 +0.101 [95% CI，0.055–0.147]）。结论：在无症状的一般人群中，基于患者年龄的风险评分，身高、体重和病史可能会改善无症状患者的识别，这些患者有 AAA 临床事件的风险。需要进一步开发和验证风险评分以检测无症状的 AAA。