Internal or external wall diameter for abdominal aortic aneurysm screening?

INTRODUCTION: The national abdominal aortic aneurysm (AAA) screening programme measures internal wall diameter; however, current UK intervention criteria use external wall diameter. Our aim was to determine the clinical significance of the difference between these two measurements. PATIENTS AND METHODS: Fifty patients on an aneurysm surveillance programme were ultrasound scanned by two experienced vascular scientists, blinded to the other's results. Maximum anteroposterior internal wall and maximum anteroposterior external wall diameters were measured. RESULTS: The median difference between internal and external diameter was 6 mm (IQR 6-7) for scientist 1 and 7 mm (IQR 5-8) for scientist 2. This was statistically significant (P < 0.0002). External wall diameter displayed less interobserver variability (3 mm vs 6 mm). CONCLUSIONS: Screening measurements underestimate aneurysm size by 6 mm and display greater variability in comparison to external wall measurements. These findings should be understood to prevent a delay in the detection and treatment of AAAs.

Theories of serial flow in intergenerational transfers.

Recent improvements in the economic position of the elderly population necessitate a more thorough understanding of the serial flow of economic supports from preceding to succeeding generations. Five theories which might extend our understanding of the decision rules employed in intergenerational transfers are discussed. They are: social exchange theory, the kin selection theory of altruism, human capital theory, social constructivist theory, and rational transfers theory. The underlying assumptions of these theories are presented and compared, and models of intergenerational transactions are developed. Comparative studies are recommended in order to gain deeper insights into the relative strengths and weaknesses of these different views of relationships between the generations.