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Original Investigation
May 26, 2020

Effect of Doxycycline on Aneurysm Growth Among Patients With Small Infrarenal Abdominal Aortic Aneurysms: A Randomized Clinical Trial

Author Affiliations
  • 1Department of Surgery, University of Nebraska School of Medicine, Omaha
  • 2Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison
  • 3Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee
  • 4Axio Research, LLC, Seattle, Washington
  • 5Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore
  • 6Genentech, Oakland, California
JAMA. 2020;323(20):2029-2038. doi:10.1001/jama.2020.5230
Key Points

Question  Does doxycycline reduce the growth of small (3.5-5.0 cm in men, 3.5-4.5 cm in women) infrarenal abdominal aortic aneurysms?

Findings  In this randomized clinical trial that included 254 adults, doxycycline 100 mg orally twice daily compared with placebo did not significantly reduce aneurysm growth at 2 years as measured by a rank score accounting for change in maximum transverse diameter and clinical outcomes of death and repair (mean increase in maximum transverse diameter of abdominal aortic aneurysm, 0.36 cm vs 0.36 cm).

Meaning  Doxycycline did not significantly reduce growth of small abdominal aortic aneurysms after 2 years.


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