Screening for aortic aneurysm: the surgical perspective

Quantifying the risks of hypertension, age, sex and smoking in patients with abdominal aortic aneurysm

BACKGROUND

The prevalence of abdominal aortic aneurysm (AAA) in a community-based sample of men and women aged 65-79 years was correlated with known risk factors. In addition, the effect of high blood pressure and the use of antihypertensive medication on growth of AAAs were studied.

METHODS

Aortic diameter was assessed by ultrasonography and data on risk factors were collected by self-administered questionnaire for 5356 men and women as part of a randomized controlled trial.

RESULTS

Current hypertension increased the risk of having an aortic aneurysm by 30-40 per cent while use of antihypertensive medication increased the risk by 70-80 per cent, adjusting for current blood pressure. There was no clear relationship between hypertension and growth rates of existing aneurysms in this study, although these results were largely from data on small aneurysms. Men were nearly six times more likely to develop an AAA than women; the risk increased by 40 per cent every 5 years after the age of 65 years. Smoking was an independent risk factor for AAA, with level of exposure being more significant than duration.

CONCLUSION

Male sex, smoking and hypertension are strong risk factors for the development of AAA. In this study hypertension did not significantly increase the growth rate of existing aneurysms. Smoking remains the most important avoidable risk factor for AAA. The analyses presented here suggest that selection for screening, other than by age and sex, is not worthwhile.

Part II. Evidence-based medicine: a passing fancy or the future of primary care?

Reliable experimental evidence provides a firm scientific foundation for only a minority of the clinical decisions primary care practitioners must make each day. Thus clinicians' experience and judgment must complement and supplement their knowledge of published research studies. This presents a dynamic and difficult challenge to the practitioner--one that is magnified when combined with the never ending influx of medical information, with patients' and physicians' uneasiness with clinical uncertainty, and with new external pressures to standardize care. With these factors in mind, this article will review evidence-based medicine, a process and philosophy for the practice and teaching of clinical medicine that has sparked much controversy in recent years. Clinical scenarios commonly encountered in adult primary care--acute low back pain, hypertension, and screening for vascular disease--illustrate some strengths and limitations of evidence-based medicine.