Department of Veterans Affairs Cooperative Studies Program Coordinating Center, West Haven, Connecticut 2Yale School of Public Health, Yale University, West Haven, Connecticut.
Department of Veterans Affairs Cooperative Studies Program Coordinating Center, West Haven, Connecticut 2Yale School of Public Health, Yale University, West Haven, Connecticut3Department of Rehabilitation Sciences, University of Hartford, West Hartford, C.
JAMA Surg. 2015 Jan;150(1):44-50. doi: 10.1001/jamasurg.2014.2025.
Because of the high mortality rate after rupture of small abdominal aortic aneurysms (AAAs), surveillance is recommended to detect aneurysm expansion; however, the effects of clinical risk factors on long-term patterns of AAA expansion are poorly characterized.
To identify significant clinical risk factors associated with the AAA expansion rate for both constant and accelerated expansion trajectories.
DESIGN, SETTING, AND PARTICIPANTS: A multivariate mixed-effects model was established to identify clinical risk factors associated with the AAA expansion rate. Separate shape factor analysis was used to characterize steady vs accelerated expansion over time. Five hundred sixty-seven patients hospitalized at Veterans Affairs medical centers were randomized to the surveillance arm of the Aneurysm Detection and Management (ADAM) study conducted by the Veterans Affairs Cooperative Studies Program from 1992 to 2000. The patients had an AAA with a maximum diameter from 3.0 to 5.4 cm, which was monitored until a 5.5-cm maximum diameter was reached or the aneurysm became symptomatic. Thirty-three participants were not included in this analysis owing to missing or extraneous values in key predictor variables. The mean (SD) follow-up time was 3.7 (2.0) years.
The primary outcome measure was the AAA expansion rate, determined by measurement of the maximum diameter by ultrasonography at regular intervals. The objective to assess the association of clinical variables with the expansion of the AAA was formulated after data collection.
The mean (SD) linear expansion rate of AAAs was 0.26 (0.01) cm/y. Current smoking was associated with a 0.05 (0.01)-cm/y increase in the linear expansion rate (95% CI, 0.25-0.28; P < .001), diastolic blood pressure with a 0.02 (0.01)-cm/y increase per 10 mm Hg (95% CI, 0.01-0.04; P = .001), and diabetes mellitus with a 0.11 (0.02)-cm/y decrease (95% CI, 0.07-0.16; P < .001). Diastolic blood pressure and baseline AAA diameter were associated with accelerated AAA expansion (P = .001 and P < .001, respectively).
Smoking cessation and control of diastolic blood pressure are direct actions that should be taken to reduce the rate of AAA expansion. Other clinical risk factors, except for diabetes, were not associated with the AAA expansion rate. This study also provides evidence of differing trajectories in AAA expansion over time, a finding that merits further investigation.
由于小的腹主动脉瘤（AAA）破裂后的死亡率很高，因此建议进行监测以发现动脉瘤的扩张；然而，临床危险因素对长期 AAA 扩张模式的影响仍描述不佳。
确定与 AAA 扩张率相关的显著临床危险因素，包括恒定扩张率和加速扩张率。
设计、地点和参与者：建立了一个多变量混合效应模型，以确定与 AAA 扩张率相关的临床危险因素。分别使用形状因子分析来描述随时间的稳定或加速扩张。1992 年至 2000 年，退伍军人事务合作研究计划（Veterans Affairs Cooperative Studies Program）开展的腹主动脉瘤检测和管理（Aneurysm Detection and Management，ADAM）研究中，退伍军人事务医疗中心的 567 名患者被随机分配到监测组。这些患者的 AAA 最大直径为 3.0 至 5.4cm，在达到 5.5cm 最大直径或动脉瘤出现症状之前，对其进行监测。由于关键预测变量存在缺失或异常值，有 33 名参与者未纳入本分析。平均（SD）随访时间为 3.7（2.0）年。
主要结局指标为通过定期超声测量最大直径确定的 AAA 扩张率。在数据收集后制定了评估临床变量与 AAA 扩张关联的目标。
AAA 的平均（SD）线性扩张率为 0.26（0.01）cm/y。当前吸烟与线性扩张率增加 0.05（0.01）cm/y 相关（95%CI，0.25-0.28；P<0.001），舒张压每增加 10mmHg 与线性扩张率增加 0.02（0.01）cm/y 相关（95%CI，0.01-0.04；P=0.001），糖尿病与线性扩张率降低 0.11（0.02）cm/y 相关（95%CI，0.07-0.16；P<0.001）。舒张压和基线 AAA 直径与加速 AAA 扩张相关（P=0.001 和 P<0.001）。
戒烟和控制舒张压是降低 AAA 扩张率的直接措施。除糖尿病外，其他临床危险因素与 AAA 扩张率无关。本研究还提供了 AAA 随时间扩张轨迹不同的证据，这一发现值得进一步研究。
