A study by the United Kingdom Small Aneurysm Trial participants showed no benefit in five-year survival from early repair of abdominal aortic aneurysms (AAAs) up to 5.5 cm in diameter, and this result has recently been confirmed by a large American trial. The United Kingdom investigators now report data on survival after an average of eight years of follow-up.
From 93 hospitals in the United Kingdom, the authors identified 1,276 patients with infrarenal AAAs that were 4.0 to 5.5 cm in diameter. Consent for randomization was obtained from 1,090 subjects, who were assigned to either early surgical repair or serial ultrasonographic surveillance. Those in the surveillance group were subsequently offered surgery if the aneurysm grew larger than 5.5 cm or expanded by more than 1 cm in a given year, if repair of a proximal or iliac aneurysm was scheduled, or if the aneurysm became symptomatic. More than one half of the surveillance group eventually had surgical repair. Rates of smoking cessation were monitored, and success rates after one year were verified by serum measurement of nicotine metabolite (cotinine).
Short-term (30 days postoperative) mortality rates were not significantly higher among patients in the surveillance group who later underwent surgical repair (7.2 percent mortality) versus those assigned to early repair (5.5 percent). As noted in the earlier report of this trial, after five years of follow-up there was no significant difference in survival with early aneurysm repair. With longer-term follow-up data available, a small mortality benefit was seen with early repair (53 percent in the early surgery group versus 45 percent in the surveillance and later repair group). The authors considered the possibility that the surveillance group’s survival disadvantage could be due to increased rates of aneurysm rupture, but there was no strong evidence to support that hypothesis. Compared with men, women had almost three times the risk of death from aneurysm rupture (14 percent versus 5 percent).
The trial authors noted that after one year of follow-up, smoking rates in the surveillance group were substantially higher than rates in the early-surgery group (48 percent versus 28 percent). They postulated that the greater success with smoking cessation among those assigned to early surgery might explain their overall survival advantage.
The authors concluded that with longer-term follow-up, a modest survival benefit became apparent for early surgical repair of small AAAs. Women had higher rates of death from aneurysm rupture than men did, and they may be less appropriate candidates for surveillance.