Smoking, lung function and the prognosis of abdominal aortic aneurysm. The UK Small Aneurysm Trial Participants

BACKGROUND: the UK Small Aneurysm Trial was established to test the benefit of prophylactic elective surgery for small abdominal aortic aneurysms (4.0-5.5 cm in diameter) and identify prognostic risk factors, including smoking. PATIENTS, METHODS AND OUTCOMES: one thousand and ninety patients (902 men and 188 women, mean age 69.3 years) were randomised to either early elective surgery or ultrasonography surveillance until the aneurysm diameter exceeded 5. 5 cm, mean follow-up was 4.6 years. Baseline assessments included lung function tests and cotinine (a smoking marker). The principal outcome measures were all-cause mortality and aneurysm rupture. RESULTS: during the course of the trial, aneurysm rupture was diagnosed in 25 patients and 309 patients died. Whereas self-reported smoking status was not significantly associated with survival, patients without any trace of plasma cotinine had a significantly improved long-term (6-year) survival, p=0.02. Current smokers had a lower FEV(1)than past- and never-smokers. FEV(1)was the most powerful predictor of long-term (6-year) survival, the crude death rates per 100 person-years were 9.1, 6.9 and 4.6 for those with FEV(1) 2.5 l respectively, p=0.001. Moreover, the rupture rate was 1.9% per year for patients positive for plasma cotinine compared with 0.5% in those without trace of plasma cotinine, p=0.004. CONCLUSIONS: self-reported smoking status underestimates the effect of continued smoking on the prognosis of patients with small abdominal aortic aneurysm. Patients with high plasma cotinine concentrations (smokers) have an increased risk of aneurysm rupture and poorer long-term survival.