PubMed Health⌕ Search

Biomedical subjects

H A Ashton

Publications and source records attributed to H A Ashton.

At least 19 recordsLinked to original sources
PubMed2002

The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial.

BACKGROUND: Opposing views have been published on the importance of ultrasound screening for abdominal aortic aneurysms. The Multicentre Aneurysm Screening Study was designed to assess whether or not such screening is beneficial. METHODS: A population-based sample of men (n=67800) aged 65-74 years was enrolled, and each individual randomly allocated to either receive an invitation for an abdominal ultrasound scan (invited group, n=33839) or not (control group, n=33961). Men in whom abdominal aortic aneurysms (> or =3 cm in diameter) were detected were followed-up with repeat ultrasound scans for a mean of 4.1 years. Surgery was considered on specific criteria (diameter > or =5.5 cm, expansion > or =1 cm per year, symptoms). Mortality data were obtained from the Office of National Statistics, and an intention-to-treat analysis was based on cause of death. Quality of life was assessed with four standardised scales. The primary outcome measure was mortality related to abdominal aortic aneurysm. FINDINGS: 27147 of 33839 (80%) men in the invited group accepted the invitation to screening, and 1333 aneurysms were detected. There were 65 aneurysm-related deaths (absolute risk 0.19%) in the invited group, and 113 (0.33%) in the control group (risk reduction 42%, 95% CI 22-58; p=0.0002), with a 53% reduction (95% CI 30-64) in those who attended screening. 30-day mortality was 6% (24 of 414) after elective surgery for an aneurysm, and 37% (30 of 81) after emergency surgery. INTERPRETATION: Our results provide reliable evidence of benefit from screening for abdominal aortic aneurysms.

Aged↗
PubMed2002

Randomized clinical trial of screening for abdominal aortic aneurysm in women.

BACKGROUND: Screening for abdominal aortic aneurysm (AAA) is commonly restricted to men. Recent studies have indicated a possible increase in deaths due to ruptured AAA in women, and a higher rate of rupture in women than in men. The present report details results from a randomized controlled trial that assessed the effects of screening women for AAA. METHODS: Some 9342 women aged 65-80 years were entered into the trial and randomized to age-matched screen and control groups. A single ultrasonographic scan was offered to women in the screening arm of the study. Women with an AAA received follow-up scans, and were considered for elective surgery if certain criteria were met. RESULTS: The prevalence of AAA was six times lower in women (1.3 per cent) than in men (7.6 per cent). Over 5- and 10-year follow-up intervals, the incidence of rupture was the same in the screened and control groups of women. CONCLUSION: Screening women for AAA is neither clinically indicated nor economically viable.

Aged↗
PubMed2002

Late results concerning feasibility and compliance from a randomized trial of ultrasonographic screening for abdominal aortic aneurysm.

BACKGROUND: The study was an update at 10 years of a randomized trial of the efficacy of screening for abdominal aortic aneurysm (AAA). The extent of benefit, feasibility and compliance were examined, and reasons why this intervention may fail a proportion of those screened were identified. METHODS: A total of 6058 men aged 65 years and over were randomized to a group invited to attend ultrasonographic screening or to a control group. The mortality rate from AAA in the two arms of the trial was compared using a Poisson model. Analyses were by intention to treat. RESULTS: There was a 21 per cent reduction in mortality rate from AAA over the 10-year follow-up (relative risk 0.79 (95 per cent confidence interval 0.53 to 1.40)). The observed relative mortality reduction peaked at 4 years with a 52 per cent reduction in the study group. Eighteen of 24 AAA deaths in the study group were among those who did not attend the first screen, or failed to comply with the follow-up protocol. CONCLUSION: A greater awareness of the benefits of full participation in a screening programme could provide a larger and sustained mortality reduction.

Aged↗
PubMed2002

Probabilities of progression of aortic aneurysms: estimates and implications for screening policy.

BACKGROUND: Screening for abdominal aortic aneurysm, and intervention with elective repair, can reduce the incidence of aneurysmal rupture by a half. If a screening programme is implemented, it is essential to determine appropriate follow up intervals for rescreening. This paper estimates probabilities of progression growth of aortic diameter to provide evidence for this. METHODS: Data were taken from 2342 men aged 65-80 screened in the Chichester randomised control trial, who have been followed up for an average of 11 years. Aortic diameter was modelled as a Markov process with four categories: <30 mm (normal), 30-44 mm, 45-54 mm, and > or =55 mm. Estimates of the probabilities of progressing to each higher category were obtained. RESULTS: The probabilities of progression increased with greater initial aortic diameter. The estimated rates/year were 0.018 (95% confidence interval 0.014 to 0.023), 0.16 (0.12 to 0.20), and 0.49 (0.35 to 0.70) respectively for moving up one category. The probabilities of moving from <30 mm to > or =55 mm were estimated as 1% in 5 years and 12% in 15 years, while the corresponding figures for moving from 45-54 mm to > or =55 mm were 91% and 99%. There were differences in rates of progression according to age, with men over 70 years having rates about three times those of men under 70. CONCLUSIONS: It seems unnecessary to follow up men with normal aortic diameter as they experience a low probability of reaching criteria for surgery even within 15 years. However, follow up intervals should be progressively shorter for those with greater aortic diameter, especially in those aged over 70. Active follow up, for example every 3 months, is appropriate for men with an aortic diameter of 45-54 mm.

Aged↗
PubMed2001

The long-term benefits of a single scan for abdominal aortic aneurysm (AAA) at age 65.

AIM: To investigate the efficacy of a single ultrasonic scan at age 65 to identify patients at risk from ruptured abdominal aortic aneurysm (AAA). METHOD: A total of 6058 men aged 64-81 were recruited to a randomised trial, and 3000 were invited to attend a single screening test. An additional population of 1011 men was offered screening as they reached age 65. If a normal aorta was identified in this sub-group, further scans were offered at two-yearly intervals. Follow up and treatment of those identified as having an aortic dilatation of 3 cm or greater was undertaken. All subject groups were monitored for deaths occurring over the study period, and date and cause of death were recorded. RESULTS: A total of 2212 men attended screening in the randomised trial; the overall compliance was 74%, and prevalence of AAA was 7.7%. Compliance decreased, and prevalence increased, with age. Mortality from ruptured AAA was reduced by 68% at 5 years (screened group compared to the age-matched control population), and by 42% in the study arm (screened and refusers) compared with controls. The benefit persisted at ten years (53% and 21% respectively). Of the uncontrolled sample of 1011 men offered a scan at age 65, 681 attended and 649 of these were found to have a normal aortic diameter; re-screening demonstrated new aneurysm development in 4% over ten years. The aortic diameters of the new AAAs were under 4 cm and would therefore have a low risk of rupture.1 Mortality from rupture in all those with an initially normal aortic diameter was low, at 1 case per 1000 scans over ten years. CONCLUSION: Screening once for AAA at age 65 can identify the majority of AAA that are of clinical significance and can identify a large population at low risk from rupture who do not require surveillance. This policy has been effective when combined with selective treatment in reducing the risk of rupture for ten years in those who attend the screening programme.

Aged↗
PubMed2001

Serum elastin peptides in the preoperative evaluation of abdominal aortic aneurysms.

OBJECTIVE: Serum elastin peptides (SEP) have been reported to be associated with the expansion of small abdominal aortic aneurysms (AAA). Consequently, SEP-measurements may predict future rupture, and allow further selection for surgery in cases referred for surgery due to size. MATERIAL AND METHODS: SEP was measured in 90 men and 10 women with AAA, who were considered for surgery as part of the Chichester aneurysm screening programme. Sixty-one patients were electively operated and four because of symptoms. The rest were followed up further. Twelve of these experienced ruptured AAA later. RESULTS: No correlation between last measured AAA-diameter, annual expansion rate and SEP was noticed. However, SEP levels were significantly higher in cases rupturing later, persisting after adjustment for age, sex, and last measured AAA-size. ROC curve analysis concerning SEP as a predictor of rupture later showed an optimal sensitivity and specificity of 67% and 60%, respectively, similar with last measured AAA-size. By combining AAA-size and SEP, the optimal sensitivity and specificity reached 83% and 66%, respectively. CONCLUSION: One sampling of SEP combined with AAA-size in patients referred for AAA surgery may be a clinical useful indicator of high rupture risk.

Aged↗
PubMed2001

Indicators of infection with Chlamydia pneumoniae are associated with expansion of abdominal aortic aneurysms.

PURPOSE: Chlamydia Pneumoniae has been shown to be associated with atherosclerosis, myocardial infarction, and abdominal aortic aneurysms (AAAs). The possible association between AAA expansion and C pneumoniae infection was therefore assessed. METHODS: Blood samples were taken from patients with an AAA that was considered for surgical repair after having been diagnosed by means of the Chichester aneurysm screening program (UK) as having an initially infrarenal aortic diameter of 3.0 to 5.9 cm. The patients were examined prospectively for as long as 11.5 years (mean, 4.1 years) with ultrasound scanning. Of 110 patients considered for surgery, 90 men and 10 women had blood samples taken. Their IgG and IgA antibodies against C pneumoniae were measured by means of a microimmunofluorescence test. Unpaired t tests, multiple linear regression analyses, and logistic regression analyses were used for statistical analysis. RESULTS: A total of 44% (95% CI, 31%-55%) of the men with an AAA had an IgA titer of 64 or more, an IgG titer of 128 or more, or both, compared with 10% of the women with an AAA (OR = 7.2; 95% CI, 1.05-160.8). A titer of IgG of 128 or more was significantly associated with higher expansion (5.3 vs 2.6 mm per year), even after adjustment for initial AAA size and age. A significant positive correlation between both IgA and IgG titers and mean annual expansion was observed (r = 0.28; 95% CI, 0.05-0.49; and r = 0.45; 95% CI, 0.24-0.62, respectively), persisting after adjusting for initial AAA size and age. An IgG titer of 128 or more was present significantly more often in cases with an expansion greater than 1 cm annually (adjusted OR = 12.6; 95% CI, 1.37-293). CONCLUSION: A high proportion of men with an AAA has signs of infection with C pneumoniae. The progression of their AAAs was positively correlated with the presence of indicators of C pneumoniae infection.

Aged↗
PubMed2000

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.

Age Factors↗
PubMed1999

A 14-year experience with 6 cm as a criterion for surgical treatment of abdominal aortic aneurysm.

BACKGROUND: It remains unclear when to recommend operation for an asymptomatic abdominal aortic aneurysm (AAA). This study examined a prospective series of patients for whom standard criteria were applied. METHODS: Some 584 consecutive patients with an AAA of diameter 3 cm or greater detected by ultrasonographic screening have been observed for up to 14 years. Repeat ultrasonographic examinations have been performed at intervals. Surgery was not considered unless the aneurysm measured 6 cm in diameter, expanded at a rate equivalent to at least 1 cm per year, caused the patient symptoms, or an iliac aneurysm was present that required treatment. RESULTS: Operation was performed on 127 patients; the majority (80; 63 per cent) had an aneurysm that reached 6 cm in diameter. Use of the above criteria prevented rupture in all but 24 (4 per cent) of the 584 patients over the 14-year interval. Of these 24 patients, 11 were unfit for planned surgery and eight declined operation or follow-up. Rupture in the five remaining patients (1 per cent) who were available for treatment compared favourably with the reported 30-day mortality rate for elective surgical treatment of 1.4-12 per cent. CONCLUSION: Repeated observation is preferable to surgical intervention until an aortic aneurysm measures 6 cm in diameter, expands by 1 cm per annum or causes symptoms. Presented as a poster to the 52nd Annual Meeting of the Society for Vascular Surgery, San Diego, California, USA, June 1998

Aged↗
PubMed1999

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.

Age Factors↗
PubMed1998

Abdominal aortic aneurysm rupture rates: a 7-year follow-up of the entire abdominal aortic aneurysm population detected by screening.

PURPOSE: The goal of the current study was to identify the risk of rupture in the entire abdominal aortic aneurysm (AAA) population detected through screening and to review strategies for surgical intervention in light of this information. METHODS: Two hundred eighteen AAAs were detected through ultrasound screening of a family practice population of 5394 men and women aged 65 to 80 years. Subjects with an AAA of less than 6.0 cm in diameter were followed prospectively with the use of ultrasound, according to our protocol, for 7 years. Patients were offered surgery if symptomatic, if the aneurysm expanded more than 1.0 cm per year, or if aortic diameter reached 6.0 cm. RESULTS: The maximum potential rupture rate (actual rupture rate plus elective surgery rate) for small AAAs (3.0 to 4.4 cm) was 2.1% per year, which is less than most reported operative mortality rates. The equivalent rate for aneurysms of 4.5 to 5.9 cm was 10.2% per year. The actual rupture rate for aneurysms up to 5.9 cm using our criteria for surgery was 0.8% per year CONCLUSION: In centers with an operative mortality rate of greater than 2%, (1) surgical intervention is not indicated for asymptomatic AAAs of less than 4.5 cm in diameter, and (2) elective surgery should be considered only for patients with aneurysms between 4.5 and 6 cm in diameter that are expanding by more than 1 cm per year or for patients in whom symptoms develop. In centers with elective mortality rates of greater than 10% for abdominal aortic aneurysm (AAA) repair, the benefit to the patient of any surgical intervention for an asymptomatic AAA of less than 6.0 cm in diameter is questionable.

Aged↗
PubMed1998

Screening for abdominal aortic aneurysm: is opportunistic detection a realistic alternative?

OBJECTIVES: To determine whether abdominal aortic aneurysms (AAA) may be detected during investigation for concurrent disease and to assess whether opportunistic detection is a feasible alternative to a formal screening programme. DESIGN: A prospective review of previous investigations in subjects attending for aortic screening. MATERIALS AND METHODS: 276 men aged 65-80 attended the Chichester AAA screening programme. They were asked whether they had consulted their General Practitioner and whether they had undergone radiological investigation within the preceding 5 years. RESULTS: Two-hundred and sixty-one subjects had consulted their General Practitioner (94.6%) within the past 5 years. Fifty-six patients had been investigated with radiological imaging: in 22 cases (8.0%) the investigation had the potential to detect an AAA. The opportunistic detection rate was 0.4% (one AAA) in comparison to 12.0% for the screening programme (33 AAA). Imaging investigations with the potential to pick up AAA failed to detect five out of six aneurysms in this group. CONCLUSIONS: Opportunistic screening for AAA is not a realistic alternative to a formal screening programme but may improve the detection rate in the community.

Aged↗
PubMed1998

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.

Aged↗
PubMed1995

Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study.

From family medical practices 15775 men and women aged 65-80 years were identified and randomized into two groups: one group was invited for ultrasonographic screening for abdominal aortic aneurysm (AAA), and the other acted as age- and sex-matched controls. Of the 7887 invited for screening 5394 (68.4 per cent) accepted. AAA was detected in 218 (4.0 per cent overall and 7.6 per cent of men). Aortic surgery was offered to the screened group if certain criteria were met and no patient died from rupture who was fit for operation and accepted elective treatment. The incidence of rupture was reduced by 55 per cent in men in the group invited for screening, compared with controls. The incidence of rupture in women was low in both groups.

Age Factors↗
PubMed1994

Surgical workload as a consequence of screening for abdominal aortic aneurysm.

A study was performed to evaluate the surgical workload that has resulted from screening an at-risk population for abdominal aortic aneurysm (AAA) and to forecast the likely workload from an established screening programme. Over an 8-year period 8944 people aged 65-80 years were screened; 356 were found to have an AAA of 3 cm or greater in diameter. There were 288 outpatient consultations involving 171 patients, and 43 patients (4.8 per 1000 screened) had surgery during the study period. A fully operational screening programme for a population of 250,000, screening men and women at a rate of 2000 per year, would be expected to produce a surgical workload of nine or ten operations for AAA per year. Screening men only would increase this to 34 annually.

Aged↗
PubMed1994

Accuracy of ultrasound in a screening programme for abdominal aortic aneurysms.

OBJECTIVES: To assess the accuracy of ultrasound in the measurement of aortic diameter. SETTING: A general practice based screening programme for abdominal aortic aneurysm. DESIGN: (a) comparison of ultrasound with computed tomography (CT) measurement; (b) two period crossover study to assess interobserver error; (c) comparison of ultrasound measurements by technicians and radiologists. RESULTS: In 36 patients where CT showed clear maxima in anteroposterior diameter, the measurement by ultrasound was consistently less than by CT scan (mean ultrasound-CT difference -4.4 mm, range -12.3 to 2.4 mm). There was no difference in the measurements made by different ultrasonographers, but their method of measurement produced a reading for aortic diameter less than that obtained by a vascular radiologist. CONCLUSIONS: These results show that ultrasound measurement is less accurate for smaller aneurysms, consistently gives a smaller reading for aortic diameter when compared with CT measurement, but was reproducible between ultrasonographers. Monitoring and audit of aneurysm screening programmes to assess accuracy and reproducibility of ultrasound measurement is recommended.

Aged↗
PubMed1993

Is surgery necessary for abdominal aortic aneurysm less than 6 cm in diameter?

During 8 years of an ultrasound screening programme for abdominal aortic aneurysm (AAA), 8944 people aged 65-80 years were scanned. 356 (4%) had AAA of diameter 3 cm or greater. Under our criteria repair was indicated if the aortic diameter reached 6 cm, if expansion reached 1 cm per year, or if the AAA caused symptoms; 124 patients met these criteria. Among the 8820 screened patients who did not meet the criteria, 1 death (0.4%) was attributed to ruptured aneurysm, although the retroperitoneal haematoma had developed within 5 days of surgery for a colon tumour. The risk of aortic rupture in patients with AAA less than 6 cm diameter with these criteria (0.4%) is lower than that for elective surgery (1-8%). Surgical repair is unnecessary and possibly detrimental in such patients, provided that ultrasound surveillance is undertaken.

Aged↗