Importance Abdominal aortic aneurysms affect more than 3% of US older adults. Objective To test whether doxycycline reduces the growth of abdominal aortic aneurysm over 2 years as measured by maximum transverse diameter. Design, Setting, and Participants Parallel, 2-group, randomized clinical trial that was conducted at 22 US clinical centers between May 2013 and January 2017, and enrolled patients 50 years or older with small (3.5-5.0 cm for men, 3.5-4.5 cm for women) infrarenal aneurysms. The final date of follow-up was July 31, 2018. Interventions Patients were randomized to receive twice daily for 2 years doxycycline 100 mg orally (as capsules) (n = 133) or placebo (n = 128). Main Outcomes and Measures The primary outcome was change in abdominal aortic aneurysm maximum transverse diameter measured from CT images at baseline and follow-up at 2 years. Patients were assigned ranks based on the maximum transverse diameter (measured or imputed) of the aorta and also if they underwent aneurysm repair or died. The ranks were converted to scores having a normal distribution to facilitate the primary analysis ("normal scores"). Results Of 261 patients randomized, no follow-up CT scans were obtained on 7 (3%), leaving a final analysis set of 129 patients assigned to doxycycline and 125 to placebo (mean [SD] age, 71.0 years [7.4 years], 35 women [14%]). The outcome normal scores used in the primary analysis were based on maximum transverse diameter (measured or imputed) in 113 patients (88%) in the doxycycline group and 112 patients (90%) in the placebo group; aneurysm repair in 13 (10%) and 9 (7%), and death in 3 (2%) and 4 (3%), respectively. The primary outcome, normal scores reflecting change in aortic diameter, did not differ significantly between the 2 groups, mean change in normal scores, 0.0262 vs -0.0258 (1-sided P = .71). Mean (SD) baseline maximum transverse diameter was 4.3 cm (0.4 cm) for doxycycline and 4.3 cm (0.4 cm) for placebo. At the 2-year follow-up, the change in measured maximum transverse diameter was 0.36 cm (95% CI, 0.31 to 0.40 cm) for 96 patients in the doxycycline group vs 0.36 cm (95% CI, 0.30 to 0.41 cm) for 101 patients in the placebo group (difference, 0.0; 95% CI, -0.07 to 0.07 cm; 2-sided P = .93). No patients were withdrawn from the study because of adverse effects. Joint pain occurred in 84 of 129 patients (65%) with doxycycline and 79 of 125 (63%) with placebo. Conclusions and Relevance Among patients with small infrarenal abdominal aortic aneurysms, doxycycline compared with placebo did not significantly reduce aneurysm growth at 2 years. These findings do not support the use of doxycycline for reducing the growth of small abdominal aortic aneurysms. Trial Registration ClinicalTrials.gov Identifier: NCT01756833.

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多西环素对肾下型腹主动脉瘤患者动脉瘤生长的影响

重要性 腹主动脉瘤影响超过 3% 的美国老年人。目的通过最大横径测量多西环素在2年内是否能减少腹主动脉瘤的生长。设计、设置和参与者 2013 年 5 月至 2017 年 1 月在美国 22 个临床中心进行的平行、2 组、随机临床试验，招募了 50 岁或以上的患者（男性为 3.5-5.0 厘米，男性为 3.5-4.5厘米（女性））肾下动脉瘤。随访的最后日期为 2018 年 7 月 31 日。 干预措施 患者随机接受每天两次口服强力霉素 100 毫克（作为胶囊）（n = 133）或安慰剂（n = 128），为期 2 年。主要结果和测量主要结果是根据基线和随访 2 年的 CT 图像测量的腹主动脉瘤最大横向直径的变化。患者根据主动脉的最大横向直径（测量或推算）以及他们是否接受了动脉瘤修复或死亡来分配等级。等级被转换为具有正态分布的分数以促进主要分析（“正态分数”）。结果 在随机分配的 261 名患者中，7 名 (3%) 未进行后续 CT 扫描，最终分析组 129 名患者分配至强力霉素组，125 名患者分配至安慰剂组（平均 [SD] 年龄，71.0 岁 [7.4 岁]， 35 名女性 [14%]）。主要分析中使用的结果正常评分基于强力霉素组 113 名患者 (88%) 和安慰剂组 112 名患者 (90%) 的最大横向直径（测量或推算）；分别有 13 名 (10%) 和 9 名 (7%) 动脉瘤修复，3 名 (2%) 和 4 名 (3%) 死亡。主要结果，反映主动脉直径变化的正常评分，两组之间没有显着差异，正常评分的平均变化为 0.0262 对 -0.0258（单侧 P = .71）。多西环素的平均 (SD) 基线最大横向直径为 4.3 厘米（0.4 厘米），安慰剂为 4.3 厘米（0.4 厘米）。在 2 年随访中，多西环素组 96 名患者测得的最大横径变化为 0.36 厘米（95% CI，0.31 至 0.40 厘米），而强力霉素组为 0.36 厘米（95% CI，0.30 至 0.41 厘米）安慰剂组 101 名患者（差异，0.0；95% CI，-0.07 至 0.07 厘米；两侧 P = .93）。没有患者因不良反应而退出研究。多西环素组 129 名患者中有 84 名（65%）发生关节疼痛，安慰剂组 125 名患者中有 79 名（63%）发生关节疼痛。结论和相关性 在肾下小腹主动脉瘤患者中，与安慰剂相比，多西环素在 2 年时并未显着降低动脉瘤的生长。这些发现不支持使用强力霉素来减少小腹主动脉瘤的生长。试验注册 ClinicalTrials.gov 标识符：NCT01756833。与安慰剂相比，多西环素在 2 年时没有显着减少动脉瘤的生长。这些发现不支持使用强力霉素来减少小腹主动脉瘤的生长。试验注册 ClinicalTrials.gov 标识符：NCT01756833。与安慰剂相比，多西环素在 2 年时没有显着减少动脉瘤的生长。这些发现不支持使用强力霉素来减少小腹主动脉瘤的生长。试验注册 ClinicalTrials.gov 标识符：NCT01756833。