Effect of Doxycycline on Aneurysm Growth Among Patients With Small Infrarenal Abdominal Aortic Aneurysms: A Randomized Clinical Trial
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Published on: August 4, 2022
B Timothy Baxter1, Jon Matsumura2, John A Curci3
1Department of Surgery, University of Nebraska School of Medicine, Omaha.
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.
Insights
Doxycycline did not significantly slow the growth of small abdominal aortic aneurysms over two years in a clinical trial. These findings do not support using doxycycline to reduce aneurysm expansion.
Area of Science:
- Cardiovascular Medicine
- Pharmacology
- Clinical Trials
Background:
- Abdominal aortic aneurysms (AAAs) affect over 3% of older adults in the US.
- Small AAAs require monitoring, and effective medical treatments are limited.
Purpose of the Study:
- To evaluate if doxycycline reduces the growth of small abdominal aortic aneurysms over a 2-year period.
- To assess the effect of doxycycline on the maximum transverse diameter of AAAs.
Main Methods:
- A parallel, 2-group, randomized clinical trial involving 261 patients aged 50+ with small infrarenal AAAs.
- Patients received either 100 mg doxycycline twice daily or a placebo for 2 years.
- The primary outcome was the change in AAA maximum transverse diameter measured by CT scans at baseline and 2-year follow-up.
Main Results:
- No significant difference in AAA growth was observed between the doxycycline and placebo groups (1-sided P=.71).
- The mean change in maximum transverse diameter at 2 years was 0.36 cm in both groups.
- Joint pain was a common side effect in both treatment arms (65% doxycycline vs. 63% placebo).
Conclusions:
- Doxycycline did not significantly reduce the growth of small infrarenal abdominal aortic aneurysms compared to placebo over 2 years.
- The study findings do not support the use of doxycycline for managing small AAAs.
- Further research may be needed to explore alternative medical therapies for AAA growth.
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