O-015 - THE MEDICAL MANAGEMENT OF SMALL ABDOMINAL AORTIC ANEURYSMS: CAN WE DO BETTER?

TOPIC:
Abdominal Aortic Aneurysms
AUTHORS:
Nastasi D. (James Cook University ~ Townsville ~ Australia)
Introduction:
People with Abdominal Aortic aneurysms (AAA) suffer a high risk of adverse cardiovascular major vascular events (MVE) and peripheral vascular events (PVE). Although medical therapies such as lowering LDL-C are critical in preventing these events, people with AAA are often under treated. This study assessed the incidence of MVE and PVE in people with small AAA and modelled the theoretical benefits and costs of an intensified low density lipoprotein cholesterol (LDL-C) lowering program in this cohort.
Methods:
A total of 583 participants with AAAs measuring 30 to 54 mm were included in this study. The control of LDL-C and prescription of lipid lowering drugs were assessed by dividing participants into approximately equal groups depending on their year of recruitment into the study. The occurrence of MVE (myocardial infarction, stroke, cardiovascular death and coronary or non-coronary revascularisation) and PVE (non-coronary revascularisation, AAA repair and major amputation) were recorded prospectively and the incidence of these events was calculated using Kaplan Meier analysis. The relative risk reduction reported for these events in a previous randomised control trial (RCT) were then applied to these figures to model absolute risk reduction and numbers needed to treat (NTT) that could theoretically be achieved with a mean LDL-C lowering of 1mmol/L. The maximum allowable expense for a cost-effective intensive LDL-C lowering program was estimated using a cost utility analysis.
Results:
At entry only 28.5% of participants had an LDL-C of <1.8mmol/L and only 18.5% were prescribed a high potency statin (Atorvastatin 80mg or Rosuvastatin 40mg). The 5-year incidence of MVE and PVE were 38.1% and 44.7% respectively. It was estimated that if the mean LDL-C of the cohort had been reduced by 1mmol/L, this could have reduced the absolute risk of MVE and PVE by 6.5% (95% CI 4.4, 8.7%; NNT 15) and 5.3% (1.4, 7.5%; NNT 19) respectively. It was estimated that the maximum allowable expense for a cost-effective LDL-C lowering program would be between $1,239 AUD (€768) and $1,582 AUD (€981) per person per annum over a 5-year period.
Conclusion:
People with small asymptomatic AAA are at high risk of MVE and PVE. This study provides evidence on the possible benefits and allowable expense for a cost-effective intensive LDL-C lowering program in this population.