Introduction:_x000D_ The first studies on the normal diameter of the abdominal aorta date to the 1960s, and determined that the mean diameter in men was 21.4 mm and in women 18.7 mm. Based on these data, they considered that a diameter >30mm is sufficiently greater than the mean (+2 standard deviations, SD) to establish the limit between a normal and an aneurysmal aorta. In the 1970s, the diagnosis of abdominal aortic aneurysm (AAA) was proposed if the aortic diameter (AD) is greater than or equal to 30 mm, the currently most widely used definition. Since then, different definitions have been proposed, either establishing a cut-off point between normality and pathology, or establishing a value relative to the expected normal AD, but in all cases based on the diameters observed in the earliest studies._x000D_ _x000D_ Scientific justification:_x000D_ We currently do not have data on normal AD in the general population of our health area, and worldwide publications are based on specific populations and reflect specific moments in time, therefore, we do not have global knowledge of what is happening in the world and we do not know if the population data may have undergone changes over time. Up-to-date knowledge of normal AD could be very useful to more accurately adjust the diagnosis of AAA to the characteristics of each population group and individuals._x000D_ _x000D_ Hypothesis and objectives:_x000D_ Our hypothesis is that the current AD is lower than that reported in the literature, and that in each individual it is influenced by different factors. Probably the normal AD in general population has undergone changes over time, so the current reference values may not be valid._x000D_ Our objective is to define the current reference values of AD, to know the determining factors and to evaluate the temporal evolution._x000D_ _x000D_ Design and methodology:_x000D_ First, we designed a cross-sectional analytical observational study in 65-year-old men and women in our environment in the context of a pilot AAA population screening program. The main variable was the maximum inner-inner infrarenal AD measured with Doppler ultrasound._x000D_ Second, we designed a systematic review (SR) and meta-analysis on normal AD in the general population worldwide according to PRISMA recommendations. We used a random effects model to estimate the overall mean AD, and meta-regression analysis to study the determinant effects of AD._x000D_ _x000D_ Results:_x000D_ The overall mean AD in our health area population is 16.51mm (95%CI 16.38-16.65), significantly higher in males (17.91mm (95%CI 17.69-18.13) versus 15.25mm (95%CI 15.13-15.40)). Body size, active smoking, and a history of abdominal non-aortic aneurysm were associated with a higher AD, and dyslipidemia showed an inverse relationship. With the variables related to AD, we created an individual prediction model of normal AD according to the characteristics of each subject._x000D_ The SR included 32 studies, with a total of 941144 participants. Male sex, body surface area, and outer-to-outer ultrasound technique were significantly related to a higher DA. In men we observed geographic differences, with AD being lower in Asia and higher in Oceania. The global mean AD in Europe population has decreased significantly in the last decades._x000D_ _x000D_ _x000D_ Conclusion:_x000D_ Normal infrarenal AD in general population, both in our health area and worldwide, is associated with specific individual factors such as sex and body size, and has experienced a reduction compared to the classical reference values used up to now. In addition, there are differences according to the geographical area worldwide. Therefore, rather than being a specific value, AD is a dynamic concept that is influenced by individual and population characteristics, a fact that could imply a change in the diagnostic criteria for AAA.
Diàmetre aòrtic infrarenal normal en la població general. Definició, factors determinants i estimació individual.
Gené Mola, A. (Author). 29 Mar 2023
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis