Re-Thinking and Expanding Screening for Abdominal Aortic Aneurysm
What are event rates, incidence, early case fatality, and long-term outcome of acute abdominal aortic aneurysm (AAA) events during 2002-2014 in a prospective study, both overall and in relation to the key risk factors for aneurysm formation (smoking, hypertension, male gender, and age)?
The Oxford Vascular Study was a prospective, population-based study in Oxfordshire, United Kingdom. The incidence and outcome of acute AAA events were determined. Case ascertainment was by prospective daily searches for acute events in hospital (“hot pursuit”) and retrospective searches of hospital, primary care administrative and diagnostic coding data, and centralized death certification (“cold pursuit”) for cases missed by hot pursuit and deaths in the community. To assess the impact of screening in relation to risk factors documented in primary care, data from primary health care records for all cases, and for all of the underlying study population, were obtained (individual patient data for cases and age-/sex-specific tabular data for the population) on history of hypertension and smoking status. Event and aneurysm-related death rates were projected to the whole UK population based on the 2010 census population. Future rates were projected for 2020 and 2030.
A total of 103 incident acute AAA events were analyzed. Incidence/100,000/year was 55 in men ages 65-74 years, but increased to 112 at 75-85 years, and 298 at ≥85 years, with 66.0% of all events occurring at ≥75 years. By 2030, the total number of acute aneurysm-related deaths will be static, but over 90% will occur at age ≥75 years, 61.6% at ≥85 years, and 28.6% will be in women. If the current screening program were extended to include a repeat scan in all men age 75 years and a first scan in all women age 75 years, this would prevent about 28.1% of acute incident events, 24.9% of aneurysm-related deaths, and 37.7% of life-years lost. Smoking was a powerful risk factor for premature disease in both men and women. Hypertension was the predominant risk factor in women at all ages, but was less important in men, with only 7.1% of female cases being normotensive versus 41.3% of male cases (p < 0.0001).
The authors concluded that two thirds of acute AAAs occurred at ≥75 years of age in this prospective, population-based study.
While limited by a small analytic sample of 103 acute events, this is an important study that draws attention to the limitation of the current AAA screening strategy. The authors make a convincing argument for ‘extension of the current UK screening program to all men and women at age 75’ by drawing attention to the much higher incidence of acute AAA events at ages 75-84 years than at 64-75 years, and the higher case fatality rate at older ages.
Keywords: Aortic Aneurysm, Abdominal, Blood Pressure, Geriatrics, Hypertension, Incidence, Primary Health Care, Primary Prevention, Risk Factors, Smoking
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