Measurement of arterial stiffness in subjects with vascular disease: Are vessel wall changes more sensitive than increase in intima-media thickness?

BACKGROUND AND AIMS: It is widely accepted that subjects with vascular disease have increased arterial stiffness and intima-media thickness (IMT) when compared with healthy controls. The aim of this study was to investigate indices of arterial stiffness and IMT in the common carotid arteries (CCAs) of subjects with and without peripheral arterial disease (PAD), in order to look for evidence of change in wall quality and quantity to explain increased stiffness that has been found in the arteries of subjects with vascular disease. METHODS AND RESULTS: The arterial distension waveform (ADW), IMT, diameter and brachial blood pressure were measured to calculate Young's Modulus (E) and elastic modulus (Ep) in the common carotid arteries of subjects with and without PAD. 38 subjects with confirmed PAD were compared with 43 normal controls matched for age, sex, smoking and hypertension. The mean diameter (8.35mm [95% CI 7.93-8.77] vs. 6.93mm [6.65-7.20] P<0.001, increase 20%), IMT (0.99mm [0.92-1.07] vs. 0.88mm [0.82-0.93] P=0.020, increase 12.5%), Ep (315kPa [185-444] vs. 190kPa [164-216] P=0.034, increase 66%) and E (1383kPa [836-1930] vs. 744kPa [641-846] P=0.006, increase 86%) were all significantly higher in subjects with PAD. CONCLUSIONS: This study suggests that increased stiffness observed in subjects with peripheral vascular disease is a result of change in both quantity and quality of the arterial wall. Changes in indices of arterial stiffness were much higher than changes in IMT and diameter. These preliminary observations may be an indication that indices of arterial stiffness are a sensitive early marker of atherosclerosis.

The low incidence of surgery for non-cardiac vascular disease in UK Asians may be explained by a low prevalence of disease.

AIMS: Firstly, to compare rates of surgery for non-cardiac vascular disease in Caucasians and Asians and secondarily to assess the prevalence of peripheral arterial disease (PAD) and abdominal aortic aneurysm (AAA) in the male UK Asian population. METHODS: Analysis of a prospective database followed by an epidemiological survey of 100 unselected Pakistani males, in which demographic and anthropometric data were collected alongside aortic ultrasonography and measurement of ankle: brachial pressure index (ABPI). RESULTS: Although 14.1% of our catchment area is Asian, after correction for age, they only accounted for 64/2268 (2.8%) of procedures for PAD and AAA. Specifically, Asians were 10 times less likely to undergo AAA repair and 3 times less likely to undergo procedures for lower limb peripheral bypass, amputation and endovascular intervention. In the epidemiological study, 26 subjects had a significant history of ischaemic heart disease, 21 were diabetic, 32 had hypertension and 60 were current or ex-smokers. Median aortic diameter [IQR] was 17.6 mm [16.3-19.1 mm] and no subject had an AAA. In 200 limbs, median ABPI [IQR] was 1.12 [1.04-1.21]. Only 2 patients had an ABPI < 0.9. CONCLUSION: Despite a high prevalence of cardiovascular risk factors and ischaemic heart disease, the prevalence of PAD and AAA is much lower than would have been expected in an age- and sex-matched Caucasian population. These data suggest that the reduced incidence of surgery for PAD and AAA in UK Asians is due to a low prevalence of disease.

Peri-operative myocardial injury in patients undergoing surgery for critical limb ischaemia.

INTRODUCTION: Although up to a half of patients undergoing abdominal aortic aneurysm (AAA) repair suffer myocardial injury, as indicated by a rise in cardiac troponin I (cTnI), this is infrequently accompanied by a rise in creatine kinase (CK)-MB fraction or electrocardiogram (ECG) changes. This study compares for the first time peri-operative cTnI, CK-MB and ECG changes in patients undergoing surgery for critical lower limb ischaemia (CLI). METHODS: Twenty-nine patients (20 men, median age 75 [range, 57-95] years) were studied prospectively. cTnI, CK/CK-MB ratio and ECG were performed pre-operatively and on post-operative days 1, 2 and 3. RESULTS: Eleven (38%) patients had an elevated cTnI >0.5 ng/ml. Five (17%) patients had an elevated CK-MB fraction >4% and all of these patients had an elevated cTnI. Eleven (38%) patients had ischaemic changes on ECG including seven of 11 (64%) patients with elevated cTnI and all five patients with elevated CK-MB fraction. There was no relationship between pre-operative cardiac status, antiplatelet use or type of anaesthesia and post-operative cTnI rise. Patients with a cTnI rise were younger (p=0.01), and were more likely to have presented with gangrene (p=0.04) and have a longer operation time (p=0.01) than patients who did not demonstrate a cTnI rise. Four patients developed clinically apparent cardiac complications: cardio-pulmonary arrest (n=1), cardiogenic shock (n=1), acute CCF (n=1) and rapid atrial fibrillation (n=1). Survival at 6 months was 26 of 29 (90%) patients. CONCLUSION: These data demonstrate that over a third of patients operated for CLI sustain peri-operative myocardial injury, many of which are not clinically apparent. Pre-operative medical optimisation may improve prognosis in this group of patients.

ACE inhibitors increase type III collagen synthesis: a potential explanation for reduction in acute vascular events by ACE inhibitors.

INTRODUCTION: Large trials have shown that angiotensin converting enzyme inhibitor (ACE-I) therapy reduces the risk of myocardial infarction and stroke. Acute vascular events are thought to be initiated by plaque rupture. Animal models of atherosclerosis show an increase in extra cellular matrix when given ACE-I therapy. ACE-I therapy could influence collagen synthesis, one of the major constituents of the atherosclerotic cap. METHODS: A nested case-control study was performed within the Huntingdon Aneurysm Screening Project. Subjects were assessed for arterial disease, drug history and smoking. Blood samples were taken for a measure of collagen synthesis, the amino-terminal propeptide of type III procollagen (PIIINP), lipid levels, iron metabolism and cotinine levels. RESULTS: Information was available for 420 subjects. Thirty-five were taking ACE-I therapy and 385 were not. Mean serum PIIINP level was 3.5 microg/l (sd 1.3 microg/l, range: 1.7-16.5 microg/l. There was a marked increase in mean collagen turnover between subjects taking ACE-I therapy compared to those not. Mean PIIINP level for cases and controls was 4.26 microg/l (95% CI: 3.73-4.79 microg/l) versus 3.61 microg/l (95% CI: 3.48-3.75 microg/l). No differences were found for patients taking other antihypertensive drugs. After adjusting for age, weight, height, lipid levels and ferritin, PIIINP levels remained significantly higher in cases than controls: 4.14 microg/l (95% CI: 3.72-4.57 microg/l) versus 3.62 microg/l (95% CI: 3.49-3.75 microg/l) (P-value 0.02). DISCUSSION: These results suggest that ACE-I therapy up-regulates collagen synthesis, and could improve plaque stabilisation. This may provide an explanation for the decrease in acute vascular events observed in patients on ACE-I therapy.

LDL cholesterol is associated with small abdominal aortic aneurysms.

OBJECTIVE: To examine the relationship between serum lipids and abdominal aortic aneurysms (AAA). METHODS: Two hundred and six males (>50 years) with AAA (> or =30 mm) detected in a population based screening programme were compared with 252 age-matched male controls in a nested case-control study. Smoking status, previous medical and family histories, height, weight, blood pressure, ankle brachial pressure index (ABPI) and non-fasting lipid profile were recorded. RESULTS: Cases were found to have significantly higher LDL cholesterol than controls. LDL cholesterol was an independent predictor of the risk for aneurysms in a logistic regression model adjusting for smoking status, family history of AAA, history of ischaemic heart disease, presence of peripheral vascular disease, use of lipid lowering medication and treatment for hypertension. There was a linear effect with increased levels of LDL cholesterol increasing the risk of having a small aneurysm (test for trend p=0.03). CONCLUSION: The highly significant association between LDL cholesterol and small aneurysms suggests that LDL, possibly acting via inflammatory mediated matrix degeneration, could be an initiating factor in the development of AAA. The ability of statin therapy to prevent AAA formation requires further investigation.

Near patient cholesterol testing in patients with peripheral arterial disease.

AIMS: To assess the bias, precision and utility of the Bioscanner 2000 for near patient testing of total cholesterol (NPTC) in patients with peripheral arterial disease (PAD). METHODS: One hundred consecutive patients attending a hospital-based clinic with symptomatic PAD underwent non-fasting NPTC using finger prick blood sample and a laboratory total cholesterol (TC) using blood drawn from an antecubital fossa vein. RESULTS: The Bioscanner 2000 showed good precision with a coefficient of variation of 1.8-3.8%. NPTC was significantly lower than laboratory TC (mean (S.D.) 4.67 (1.1) vs. 5.12 (1.2) mmol/l), p < or = 0.01, paired Student's t-test. Comparing the two methods using Deming regression revealed a 15% negative bias for the Bioscanner 2000 compared to laboratory testing, which was demonstrated to be a systematic bias using a Bland-Altman plot. Almost half (46%) of the readings differed by > 0.5 mmol/l, 16% by > 1.0 mmol/l and 3% by > 2 mmol/l. This means that if the cut-off for statin treatment were taken as a TC of 5.0 or 3.5 mmol/l then, based on NPTC, alone 18 and 6% of patients, respectively, would not have received a statin. CONCLUSIONS: In the present study, NPTC significantly under-estimated TC when compared to laboratory testing. However, in the majority of cases, this would not have affected the decision to prescribe a statin and NPTC testing allows the immediate institution or titration of statin treatment.

The utilisation of superficial venous surgery for chronic venous insufficiency by the U.K. Asian population.

BACKGROUND: The epidemiology of superficial venous disease is relatively well defined in the U.K. Caucasian population. By contrast, there are currently no data available for Asians, who comprise 3.6% of the U.K., and 14.1% of this institution's catchment population. The aim of this study was to compare surgery for superficial venous disease in Caucasians and Asians in this institution, in the context of our local population. METHODS: A prospectively gathered database of all 2011 superficial venous operations performed between January 1997 and April 2002 was retrospectively analysed with regard to ethnicity. The ethnic, gender and age composition of our catchment area was determined from U.K. census data. The full institutional records of 100 Asian and 100 randomly selected age and sex-matched Caucasian patients were compared in a case control study. RESULTS: After adjusting for age and gender according to census data, Asians were 40% less likely to undergo superficial venous surgery (SVS). Considering the 2011 operated patients as a whole, Asians were significantly younger and more likely to be male. In the case control study, Asians were significantly less likely to be operated for recurrent disease and significantly more likely to be operated for advanced disease. CONCLUSIONS: Although Asians are significantly less likely to undergo SVS; those that do are more likely to be young, male and operated for skin changes and ulcers. This strongly suggests that the under-representation of Asians is due to cultural, genetic or environmental factors and unmet health care need, rather than a lower prevalence of clinically significant venous disease in the Asian population.

Effectiveness and cost of screening for abdominal aortic aneurysm: results of a population screening program.

OBJECTIVES: We undertook this study to calculate the cost per life-year gained in the first round of a screening program for abdominal aortic aneurysm (AAA) and to estimate the costs in a subsequent round. METHODS: This was an intervention study, with follow-up for ruptured aneurysms. Men older than 50 years were screened for asymptomatic AAA. Outcome measures included cost per life-year saved and number of men needed to be screened to save one life. RESULTS: The incidence of ruptured AAA was 2.6 per 10,000 person- years in the screening group and 7.1 per 10,000 person-years in the control group. Screening is estimated to have prevented 10.8 ruptured AAA and 8 deaths per year, gaining 51 life-years per year for the study population, and to have reduced the incidence of ruptured AAA by 64% (95% CI, 42%-77%). Each life-year gained during the first screening round cost $1107. To save one life, 1000 men need to be screened and 5 elective operations performed. We predict that a second round of screening can be cost neutral. CONCLUSIONS: The cost-effectiveness of screening for AAA compares favorably with screening programs for other disorders in adults.

Ethnicity and peripheral arterial disease.

INTRODUCTION: the prevalence of peripheral arterial disease (PAD) is relatively well defined for the Caucasian population. Given the susceptibility of Asians and Afro-Caribbeans to coronary heart disease and stroke respectively, and the high prevalence of cardiovascular risk factors in both groups, one would expect a high prevalence of peripheral arterial disease. METHODS: a search of MEDLINE (1966-2002) was undertaken for studies on the incidence and prevalence of PAD, abdominal aortic aneurysms (AAA) and cerebrovascular disease in different ethnic groups. RESULTS: there are very few population-based prevalence studies assessing PAD, AAA or cerebrovascular disease in non-Caucasians. A review of hospital-based series demonstrates different patterns of PAD between ethnic groups. Blacks and Asians have a tendency towards more distal occlusive disease and AAA appear to be predominantly a disease of Caucasians. It is not clear whether these studies provide a true representation of the prevalence of arterial disease in various ethnic groups or are the result of an unmet health care need. CONCLUSIONS: further studies are required to establish the prevalence, natural history and response to treatment of PAD, AAA and cerebrovascular disease in non-Caucasians. Only when this has been achieved, can clinically and cost-effective health care be delivered to affected individuals from different ethnic groups.

Accuracy of serial screening for abdominal aortic aneurysms by ultrasound.

OBJECTIVES: To assess the accuracy of screening for abdominal aortic aneurysms (AAAs) by ultrasound (US). SETTING: An aneurysm screening programme in Huntingdon. METHODS: False negative tests were identified by tracing all patients with a ruptured aneurysm who were screened and then finding the number classified as normal on US. False positive tests were identified by calculating the number of aneurysmal aortas on US that were classified as normal on CT. Measurement variability of the infrarenal aortic diameter between US and CT was estimated. RESULTS: 14 out of 93 patients with a ruptured AAA since 1991 had been screened. No ruptured aneurysm had been classified as normal on US. All 64 patients with an AAA larger than 4.5 cm on US had their aneurysm confirmed on CT. The mean difference between CT and US measurements was 4 mm. The limit of variability between CT and US was 12 mm. CONCLUSION: No false negative scans were found using a cut off point of 3 cm as abnormal. No false positives were found if subjects with an AAA exceeding 4.5 cm were referred for further procedures. A serial US screening policy has excellent screening performance, justifying its use as a screening tool.

Cecal volvulus occurring after laparoscopic appendectomy.

Less than 2% of cases of intestinal obstruction in adults is caused by cecal volvulus. Although recent abdominal surgery has been implicated, no previous case of cecal volvulus has been reported after laparoscopic appendectomy.

The incidence of small abdominal aortic aneurysms and the change in normal infrarenal aortic diameter: implications for screening.

AIM: to study the incidence of small abdominal aortic aneurysms (AAA), and to investigate what proportion of normal infrarenal aortic diameters (IAD) expand with age. METHODS: longitudinal follow-up in a population-based aneurysm screening programme. The infrarenal aortic diameter (IAD) was measured by ultrasound. A second scan was performed in subjects with a normal aorta after an average of 5.5 years. RESULTS: data were analysed from 4072 subjects, 464 with a small AAA and 3608 with a normal aorta. The infrarenal aorta expanded in 15% of subjects, but significant growth (>5 mm) occurred in only 7%. Age and initial diameter were independent predictors for aortic dilatation. The effect of diameter at first screen was non-linear. The relative risk for expansion increased dramatically for IADs over 2.5 cm (test for departure of trend: chi2=52, p<0.0001). The effect of age was also non-linear, the risk of expansion was highest in the 60-69 year old age group; test for departure of trend (chi2=13, p=0.002). The incidence of new aneurysms was 3.5 per 1000 person-years (py) (95% CI: 2.8-4.4). The highest incidence of new aneurysms was found in the 60 to 69 year old age group. CONCLUSION: only a small proportion of the population is prone to aortic dilatation. Patients over 70 with an IAD <2.5 cm can be discharged from follow-up.

The association between connective tissue laxity and the risk of an abdominal aortic aneurysm.

AIMS: to investigate whether connective tissue laxity is associated with abdominal aortic aneurysms (AAA). METHODS: a nested case control study in a population-based screening programme. The presence of pes planus, scoliosis, pectus deformities, flexible auricular cartilages and Gorling's sign were combined with the Beighton joint mobility score to form a connective tissue laxity score. The association between connective tissue laxity and the risk of AAA was investigated through a logistic regression model. Type III collagen turnover was assessed using a serum radio-immunoassay for type III procollagen (PIIINP). RESULTS: data from 231 controls (aortic diameter <2.5 cm) and 190 cases (AAA >2.9 cm) were analysed. Odds ratios (OR), adjusted for known confounders were 3.1 (95% CI: 1. 1-8.6) for the highest group of connective tissue scores and 2.4 (95% CI: 1.0-5.4) for the middle group, compared with those with no signs of abnormal connective tissue function. There was no difference in mean collagen turnover between cases and controls, nor between those with a stable AAA >4 cm and those with an expanding AAA. CONCLUSION: connective tissue laxity is associated with a higher risk of having an AAA. The collagen turnover is similar in subjects with an AAA and controls. Aneurysms may be associated with abnormal connective tissue rather than an increased breakdown of normal collagen.

Incidence among men of asymptomatic abdominal aortic aneurysms: estimates from 500 screen detected cases.

OBJECTIVES: To determine the incidence of asymptomatic abdominal aortic aneurysms and the implications for an ultrasound screening programme in England and Wales. METHODS: First screen data were obtained from the Chichester and Huntingdon screening studies and used to estimate the prevalence of abdominal aortic aneurysms. The incidence of new, asymptomatic aneurysms was estimated from the prevalence rates observed in the Huntingdon screening study. SETTING: Screening programmes in Huntingdon and Chichester using ultrasound to screen all men over the age of 50 and men over age 65 respectively. RESULTS: The prevalence of abdominal aortic aneurysms ranged between 5.32% and 8.02% and between 6.18% and 9.88% of men aged between 65 and 79 in Chichester and Huntingdon respectively. Annual incidence rates, estimated by age, rose steadily reaching a peak of 0.67% of the Huntingdon population per year at age 65. Thereafter incidence falls. Estimates of the incidence of new asymptomatic abdominal aortic aneurysms, based on the observed prevalence data, were calculated and showed a peak at age 65. CONCLUSIONS: Hypotheses are offered to explain this unexpected early peak in incidence. This information should allow the definition of the optimum age for screening, and the relative benefits of screening at different intervals if widespread screening is adopted in the future.

Ruptured abdominal aortic aneurysm in the Huntingdon district: a 10-year experience.

A study was undertaken to establish the true incidence of ruptured abdominal aortic aneurysms (RAAA) in the Huntingdon districts. RAAAs in the Huntingdon district between 1986 and 1995 were studied retrospectively. Data were collected from hospital records and hospital and community autopsies. There was a total of 139 cases of RAAA; 119 were males and 20 females, giving a M:F ratio of 6:1. The incidence of RAAAs was 17.8/100,000 person years (py) in males and 3.0/100,000 py in females. Mean age at rupture was 75.5 years in men (95% confidence intervals (CI) 74-78 years) and 80.2 in women (95% CI 78.8-83 years). There was an age-specific increase in incidence after the age of 65 years in men and after 80 years in women, although 12.6% of all RAAAs occurred in men under 65 years. In all, 100 patients were confirmed to have died of RAAA during the 10-year period. This represents 79% of all ruptures discovered. Almost three-quarters of patients did not reach the operating theatre. Of the 61 patients operated on, 29 survived (48%). The size of the aneurysm at rupture was recorded in 68 cases (49%). The mean size was 8.14 cm (SD 2.0 cm). In five cases (7.4%), rupture occurred in AAAs smaller than 6 cm. The overall mortality from RAAA in Huntingdon health district is approximately 80% and three-quarters of all deaths occurred without an operation.

The infrarenal aortic diameter in relation to age: only part of the population in older age groups shows an increase.

OBJECTIVES: To resolve whether the infrarenal aortic diameter (IAD) continues to increase throughout life; to ascertain the relationship between IAD and age, sex, body size, and smoking status, and to determine whether these factors influence the IAD over the entire range of aortic diameters or only in a proportion. SETTING: Combined cross-sectional data from two population-based screening programmes for abdominal aortic aneurysms (AAA) in Huntingdon (U.K.) and Rotterdam (The Netherlands). METHODS: The antero-posterior diameter of the infrarenal aorta was measured. The influences of age, gender, body size and smoking status were examined. RESULTS: Data were analysed from 3066 women and 8270 men. In men, mean IAD rose from 20.7 mm to 23.5 mm in the older age groups. However, IADs remained constant below the 75th perentile in men and the 85th percentile in women. Similarly only the top 15-25% of the aortic diameters were larger in smokers compared with non-smokers. CONCLUSIONS: The aortic diameter increased with age in only a minority of the population. Furthermore, known risk factors for AAA contributed to aortic dilatation in only the upper tail of the frequency distribution. Thus only 25% of men and 15% of women may be prone to aortic dilatation.

Epidemiology and potential for prevention of abdominal aortic aneurysm.

BACKGROUND: Ruptured abdominal aortic aneurysm (AAA) is a common cause of death which is preventable by elective repair of an asymptomatic AAA. METHODS: The literature was reviewed with emphasis on epidemiological studies and population-based screening surveys. RESULTS AND CONCLUSION: The prevalence of small AAA ranges between 3 and 8 per cent. The incidence of asymptomatic AAA seems to be increasing, although exact incidence estimates vary. The most important risk factors for AAA are male sex, age, family history and smoking. Hypertension is associated with a mildly increased risk, but diabetes is not associated with any increase. Primary prevention of AAA is not a realistic option. There is no evidence of an effective medical treatment to prevent growth of small AAAs, although trials with propranolol are under way. The only intervention to prevent death from aneurysm is elective repair of the asymptomatic lesion. Screening for asymptomatic AAA can reduce the incidence of rupture. However, further studies are needed to determine the cost effectiveness of screening compared with that of other health programmes.

Growth rates and risk of rupture of abdominal aortic aneurysms.

BACKGROUND: Early identification of abdominal aortic aneurysms (AAAs) may reduce the risk of death from rupture by providing the opportunity for elective repair. Before a screening policy for AAA is implemented, the growth rates of AAAs and the accompanying risk of rupture without intervention should be established. METHODS: The growth rates of AAAs were calculated using longitudinal aneurysmal growth data from screening studies in Chichester and Huntingdon. Estimates of the growth rates of AAAs and the risks of rupture over time were made taking measurement error and individual variability into account. RESULTS: Growth rate estimates were found to vary by initial aortic diameter, with a more rapid growth seen in large aneurysms (50 mm or more). The rate of aneurysm growth did not differ with age or sex. The estimated risk of rupture of an AAA with an initial diameter of 45 mm did not exceed 20-5 per cent over 5 years. An AAA with an initial diameter of 30 mm has a 4.0 per cent or less chance of rupture over 5 years. CONCLUSION: The study provides a more accurate assessment of the risk of aneurysm rupture without surgery and helps to define rescreening intervals for those with an enlarged aortic diameter.

Overview of the epidemiology of colorectal cancer.

INTRODUCTION: The epidemiology of colorectal cancer has generated more interest recently, because recent developments in genetics, molecular biology, and genetic epidemiology have increased our understanding of the role of genes in the etiology of colorectal cancer. Interactions between genetic susceptibility and environmental factors in the etiology of cancer may be easier to define. EPIDEMIOLOGY: Colorectal cancer is common in the Western world and is rare in developing countries. A sharp increase is seen in Eastern Europe and Japan. ETIOLOGY: Molecular genetics has shown that accumulation of genetic changes is important in the development of colorectal cancer. Mutations in at least four to five genes are required for the formation of a malignant tumor. Environmental mutagenic factors may determine which susceptible individuals grow carcinomas. Environmental risk factors for colorectal cancer are found in a western diet, rich in fat, meat, and animal protein and low in fiber, fruit, and vegetables. The complex interrelations between food components make it difficult to define the precise role of specific food factors. PREVENTION: Conclusive evidence of the effectiveness of primary prevention of colorectal cancer via dietary measures or nonsteroidal anti-inflammatory drugs is lacking. Secondary prevention by interrupting the adenoma carcinoma sequence is an actual possibility, its effectiveness, however, needs to be determined. Molecular genetics holds a promise for identifying populations at high risk for colorectal cancer, therefore, targeting the screening to make it more cost-effective.

Quality of the measurement of the infrarenal aortic diameter by ultrasound.

OBJECTIVES: To assess quality and variability in measurements of the infrarenal aortic diameter by ultrasound, and to recommend quality control measures to improve consistency in measurements of the infrarenal aortic diameter (IAD) in a long running screening programme. SETTING: An aneurysm screening programme in Huntingdon. METHODS: Quality of the ultrasound image was subjectively assessed by each ultrasonographer. Quality of the measurements was assessed by analysing the frequency of measurements that were outside the normal variability of the estimated true diameter. The interobserver variability was measured by analysing repeated measurements of the IAD in the same patient by two ultrasonographers, using the same scanner. The variability between different scanners was measured by analysing repeat measurements of the IAD in the same patient by the same ultrasonographer, using two scanners. The intraobserver variability was estimated by analysing all patients with three consecutive measurements of the IAD, carried out by the same ultrasonographer. RESULTS: Although the subjective assessment of the quality of the ultrasound image of the aorta varied, there were no statistically significant differences in the likelihood of obtaining measurements outside the limits of agreement between the ultrasonographers. The interobserver, intraobserver, and between scanner variability of ultrasound measurements of the IAD were all around 6 mm. CONCLUSION: The variability in ultrasound measurements of aortic diameters is acceptable for clinical decision making, and the interobserver variability is very similar to the long term intraobserver variability. Quality control measures are suggested to maintain long term consistency of ultrasound measurements of the IAD.