Early Elective Surgery or Ultrasonographic Surveillance for Small Abdominal Aortic Aneurysms - UK Small Aneurysms

Description:

The UK small aneurysm trial was a prospective, randomized, placebo-controlled multicenter study designed to evaluate whether prophylactic open surgery was associated with decreased long-term mortality risks for small aortic aneurysms.

Hypothesis:

Early elective open surgical repair of small aortic aneurysms will be associated with decreased long-term mortality from small aortic aneurysms.

Study Design

Study Design:

Patients Screened: 1,276
Patients Enrolled: 1,090
Mean Follow Up: Six years
Mean Patient Age: 65-73 years
Female: 18

Patient Populations:

Patients with asymptomatic (nontender), infrarenal, abdominal aortic aneurysms of 4.0-5.5 cm in diameter

Exclusions:

Patients unfit for elective surgery or unable to attend for follow-up or unable to give informed consent and patients with tender aneurysms

Primary Endpoints:

Mortality and survival rates at two, four, and six years after randomization

Secondary Endpoints:

30-day operative mortality rates and aneurysm rupture from surgical repair of aortic aneurysms

Drug/Procedures Used:

The patients were randomly assigned to undergo surgery or ultrasonographic (US) surveillance of aneurysm diameter. Randomization was done centrally by computer-generated simple random numbers. Surgery was performed according to normal local procedures. Patients randomized to US surveillance were reviewed at regular intervals, and results were reported to the local surgeon.

Patients with aneurysms 4.0-4.9 cm in diameter were reviewed every six months, and those with aneurysms 5.0-5.5 cm were reviewed every three months. If diameter of the aortic aneurysm exceeded 5.5 cm, the growth was more than 1 cm per year, the aneurysm became tender, or iliac or thoracic repair was needed, elective surgical repair was recommended.

One month after surgery, patients were reviewed by the participating surgeon. All deaths that occurred within two weeks of elective surgery were attributed to abdominal aortic aneurysm.

Concomitant Medications:

N/A

Principal Findings:

A total of 1,090 randomized patients who consented to randomization were assigned to either undergo early elective surgery (563 patients) or US surveillance (527 patients), and were followed for a total of six years. Baseline demographic, clinical, and biochemical characteristics were balanced among the two groups. For patients in the early-surgery group, elective surgery with a prosthetic inlay graft was performed in 517. Of the patients assigned to the US surveillance group, 489 adhered to the trial protocol. The median time to surgery in the surveillance group was 2.9 years.

Overall survival in the two groups did not differ significantly (64% vs. 64%, p=0.56). Survival was worse initially in the early-surgery group and subsequently worse in the surveillance group. The absolute differences in the risk of death by two, four, and six years, respectively, were 1.9% more, 3% less, and 0.3% more in the early-surgery group than in the surveillance group (p=0.33, p=0.29, and p=0.94). Analysis of survival by treatment received showed that the 30-day operative mortality (adjusted for age and sex) was 5.8% in the early-surgery group and 7.1% in the US surveillance group (p=0.14).

Older age, larger aneurysm diameter, lower ankle/brachial pressure index, and poorer lung function (lower FEV1) at baseline were independently related to an increased risk of death. Death from aneurysmal rupture was reported more commonly in the surveillance group (17 deaths) than in the early surgery group (six deaths).

Interpretation:

Among patients with small, asymptomatic abdominal aortic aneurysms, elective surgical repair was not associated with a long-term survival advantage compared with US surveillance. US surveillance provides an alternative method of management.

References:

Mortality results for randomised controlled trial of early elective surgery or ultrasonographic surveillance for small abdominal aortic aneurysms. The UK Small Aneurysm Trial Participants. Lancet 1998;352:1649-55.

Clinical Topics: Vascular Medicine

Keywords: Surgical Procedures, Elective, Aortic Aneurysm, Abdominal


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