Value of risk scores in the decision to palliate patients with ruptured abdominal aortic aneurysm

Background

The aim of this study was to develop a 48‐h mortality risk score, which included morphology data, for patients with ruptured abdominal aortic aneurysm presenting to an emergency department, and to assess its predictive accuracy and clinical effectiveness in triaging patients to immediate aneurysm repair, transfer or palliative care.

Methods

Data from patients in the IMPROVE (Immediate Management of the Patient With Ruptured Aneurysm: Open Versus Endovascular Repair) randomized trial were used to develop the risk score. Variables considered included age, sex, haemodynamic markers and aortic morphology. Backwards selection was used to identify relevant predictors. Predictive performance was assessed using calibration plots and the C‐statistic. Validation of the newly developed and other previously published scores was conducted in four external populations. The net benefit of treating patients based on a risk threshold compared with treating none was quantified.

Results

Data from 536 patients in the IMPROVE trial were included. The final variables retained were age, sex, haemoglobin level, serum creatinine level, systolic BP, aortic neck length and angle, and acute myocardial ischaemia. The discrimination of the score for 48‐h mortality in the IMPROVE data was reasonable (C‐statistic 0·710, 95 per cent c.i. 0·659 to 0·760), but varied in external populations (from 0·652 to 0·761). The new score outperformed other published risk scores in some, but not all, populations. An 8 (95 per cent c.i. 5 to 11) per cent improvement in the C‐statistic was estimated compared with using age alone.

Conclusion

The assessed risk scores did not have sufficient accuracy to enable potentially life‐saving decisions to be made regarding intervention. Focus should therefore shift to offering repair to more patients and reducing non‐intervention rates, while respecting the wishes of the patient and family.

Not much help

L-Serine: a Naturally-Occurring Amino Acid with Therapeutic Potential

In human neuroblastoma cell cultures, non-human primates and human beings, L-serine is neuroprotective, acting through a variety of biochemical and molecular mechanisms. Although L-serine is generally classified as a non-essential amino acid, it is probably more appropriate to term it as a "conditional non-essential amino acid" since, under certain circumstances, vertebrates cannot synthesize it in sufficient quantities to meet necessary cellular demands. L-serine is biosynthesized in the mammalian central nervous system from 3-phosphoglycerate and serves as a precursor for the synthesis of the amino acids glycine and cysteine. Physiologically, it has a variety of roles, perhaps most importantly as a phosphorylation site in proteins. Mutations in the metabolic enzymes that synthesize L-serine have been implicated in various human diseases. Dosing of animals with L-serine and human clinical trials investigating the therapeutic effects of L-serine support the FDA's determination that L-serine is generally regarded as safe (GRAS); it also appears to be neuroprotective. We here consider the role of L-serine in neurological disorders and its potential as a therapeutic agent.

Sex differences in mortality after abdominal aortic aneurysm repair in the UK

BACKGROUND

The UK abdominal aortic aneurysm (AAA) screening programmes currently invite only men for screening because the benefit in women is uncertain. Perioperative risk is critical in determining the effectiveness of screening, and contemporary estimates of these risks in women are lacking. The aim of this study was to compare mortality following AAA repair between women and men in the UK.

METHODS

Anonymized data from the UK National Vascular Registry (NVR) for patients undergoing AAA repair (January 2010 to December 2014) were analysed. Co-variables were extracted for analysis by sex. The primary outcome measure was in-hospital mortality. Secondary outcome measures included mortality by 5-year age groups and duration of hospital stay. Logistic regression was performed to adjust for age, calendar time, AAA diameter and smoking status. NVR-based outcomes were checked against Hospital Episode Statistics (HES) data.

RESULTS

A total of 23 245 patients were included (13·0 per cent women). Proportionally, more women than men underwent open repair. For elective open AAA repair, the in-hospital mortality rate was 6·9 per cent in women and 4·0 per cent in men (odds ratio (OR) 1·48, 95 per cent c.i. 1·08 to 2·02; P = 0·014), whereas for elective endovascular AAA repair it was 1·8 per cent in women and 0·7 per cent in men (OR 2·86, 1·72 to 4·74; P < 0·001); the results in HES were similar. For ruptured AAA, there was no sex difference in mortality within the NVR; however, in HES, for ruptured open AAA repair, the in-hospital mortality rate was higher in women (33·6 versus 27·1 per cent; OR 1·36, 1·16 to 1·59; P < 0·001).

CONCLUSION

Women have a higher in-hospital mortality rate than men after elective AAA repair even after adjustment. This higher mortality may have an impact on the benefit offered by any screening programme offered to women.

Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years

BACKGROUND

The erosion of the early mortality advantage of elective endovascular aneurysm repair (EVAR) compared with open repair of abdominal aortic aneurysm remains without a satisfactory explanation.

METHODS

An individual-patient data meta-analysis of four multicentre randomized trials of EVAR versus open repair was conducted to a prespecified analysis plan, reporting on mortality, aneurysm-related mortality and reintervention.

RESULTS

The analysis included 2783 patients, with 14 245 person-years of follow-up (median 5·5 years). Early (0-6 months after randomization) mortality was lower in the EVAR groups (46 of 1393 versus 73 of 1390 deaths; pooled hazard ratio 0·61, 95 per cent c.i. 0·42 to 0·89; P = 0·010), primarily because 30-day operative mortality was lower in the EVAR groups (16 deaths versus 40 for open repair; pooled odds ratio 0·40, 95 per cent c.i. 0·22 to 0·74). Later (within 3 years) the survival curves converged, remaining converged to 8 years. Beyond 3 years, aneurysm-related mortality was significantly higher in the EVAR groups (19 deaths versus 3 for open repair; pooled hazard ratio 5·16, 1·49 to 17·89; P = 0·010). Patients with moderate renal dysfunction or previous coronary artery disease had no early survival advantage under EVAR. Those with peripheral artery disease had lower mortality under open repair (39 deaths versus 62 for EVAR; P = 0·022) in the period from 6 months to 4 years after randomization.

CONCLUSION

The early survival advantage in the EVAR group, and its subsequent erosion, were confirmed. Over 5 years, patients of marginal fitness had no early survival advantage from EVAR compared with open repair. Aneurysm-related mortality and patients with low ankle : brachial pressure index contributed to the erosion of the early survival advantage for the EVAR group. Trial registration numbers: EVAR-1, ISRCTN55703451; DREAM (Dutch Randomized Endovascular Aneurysm Management), NCT00421330; ACE (Anévrysme de l'aorte abdominale, Chirurgie versus Endoprothèse), NCT00224718; OVER (Open Versus Endovascular Repair Trial for Abdominal Aortic Aneurysms), NCT00094575.

Meta-analysis of the current prevalence of screen-detected abdominal aortic aneurysm in women

Background

Although women represent an increasing proportion of those presenting with abdominal aortic aneurysm (AAA) rupture, the current prevalence of AAA in women is unknown. The contemporary population prevalence of screen‐detected AAA in women was investigated by both age and smoking status.

Methods

A systematic review was undertaken of studies screening for AAA, including over 1000 women, aged at least 60 years, done since the year 2000. Studies were identified by searching MEDLINE, Embase and CENTRAL databases until 13 January 2016. Study quality was assessed using the Newcastle–Ottawa scoring system.

Results

Eight studies were identified, including only three based on population registers. The largest studies were based on self‐purchase of screening. Altogether 1 537 633 women were screened. Overall AAA prevalence rates were very heterogeneous, ranging from 0·37 to 1·53 per cent: pooled prevalence 0·74 (95 per cent c.i. 0·53 to 1·03) per cent. The pooled prevalence increased with both age (more than 1 per cent for women aged over 70 years) and smoking (more than 1 per cent for ever smokers and over 2 per cent in current smokers).

Conclusion

The current population prevalence of screen‐detected AAA in older women is subject to wide demographic variation. However, in ever smokers and those over 70 years of age, the prevalence is over 1 per cent.

Significant in older women who smoke

Individual-patient meta-analysis of three randomized trials comparing endovascular versus open repair for ruptured abdominal aortic aneurysm

BACKGROUND

The benefits of endovascular repair of ruptured abdominal aortic aneurysm remain controversial, without any strong evidence about advantages in specific subgroups.

METHODS

An individual-patient data meta-analysis of three recent randomized trials of endovascular versus open repair of abdominal aortic aneurysm was conducted according to a prespecified analysis plan, reporting on results to 90 days after the index event.

RESULTS

The trials included a total of 836 patients. The mortality rate across the three trials was 31.3 per cent for patients randomized to endovascular repair/strategy and 34.0 per cent for those randomized to open repair at 30 days (pooled odds ratio 0.88, 95 per cent c.i. 0.66 to 1.18), and 34.3 and 38.0 per cent respectively at 90 days (pooled odds ratio 0.85, 0.64 to 1.13). There was no evidence of significant heterogeneity in the odds ratios between trials. Mean(s.d.) aneurysm diameter was 8.2(1.9) cm and the overall in-hospital mortality rate was 34.8 per cent. There was no significant effect modification with age or Hardman index, but there was indication of an early benefit from an endovascular strategy for women. Discharge from the primary hospital was faster after endovascular repair (hazard ratio 1.24, 95 per cent c.i. 1.04 to 1.47). For open repair, 30-day mortality diminished with increasing aneurysm neck length (adjusted odds ratio 0.69 (95 per cent c.i. 0.53 to 0.89) per 15 mm), but aortic diameter was not associated with mortality for either type of repair.

CONCLUSION

Survival to 90 days following an endovascular or open repair strategy is similar for all patients and for the restricted population anatomically suitable for endovascular repair. Women may benefit more from an endovascular strategy than men and patients are, on average, discharged sooner after endovascular repair.

Hospital trends of admissions and procedures for acute leg ischaemia in England, 2000-2011

INTRODUCTION

Acute leg ischaemia (ALI) is a common vascular emergency for which new minimally invasive treatment options were introduced in the 1990s. The aim of this study was to determine recent hospital trends for ALI in England and to assess whether the introduction of the new treatment modalities had affected management.

METHODS

Routine hospital data covering ALI were provided by Hospital Episode Statistics for the years 2000 to 2011 and mortality data were obtained from the Office for National Statistics. All data were age standardised, reported per 100,000 of the population, and stratified by age band (60-74 years and ≥75 years) and sex.

RESULTS

Hospital admissions have risen significantly from 60.3 to 94.3 per 100,000 of the population, with an average annual increase of 6.2% since 2003 (p<0.001). The rise was greater in the older age group (from 79.9 to 134.4 vs 49.3 to 73.0) and yet procedures for ALI have shown a significant decrease since 2000 from 14.3 to 12.4 per 100,000 (p=0.013), independent of age and sex. Open embolectomy of the femoral artery remains the most common procedure and the proportion of endovascular interventions showed only a small increase. Only a few deaths were attributed to ALI (range: 95-150 deaths per year).

CONCLUSIONS

Hospital workload for ALI has increased, particularly since 2003, but this trend does not appear to have translated into increased endovascular or surgical activity.

Outcomes after endovascular or open repair for degenerative descending thoracic aortic aneurysm using linked hospital data

BACKGROUND

The population-based effectiveness of thoracic endovascular aortic repair (TEVAR) versus open surgery for descending thoracic aortic aneurysm remains in doubt.

METHODS

Patients aged over 50 years, without a history of aortic dissection, undergoing repair of a thoracic aortic aneurysm between 2006 and 2011 were assessed using mortality-linked individual patient data from Hospital Episode Statistics (England). The principal outcomes were 30-day operative mortality, long-term survival (5 years) and aortic-related reinterventions. TEVAR and open repair were compared using crude and multivariable models that adjusted for age and sex.

RESULTS

Overall, 759 patients underwent thoracic aortic aneurysm repair, mainly for intact aneurysms (618, 81·4 per cent). Median ages of TEVAR and open cohorts were 73 and 71 years respectively (P < 0·001), with more men undergoing TEVAR (P = 0·004). For intact aneurysms, the operative mortality rate was similar for TEVAR and open repair (6·5 versus 7·6 per cent; odds ratio 0·79, 95 per cent confidence interval (c.i.) 0·41 to 1·49), but the 5-year survival rate was significantly worse after TEVAR (54·2 versus 65·6 per cent; adjusted hazard ratio 1·45, 95 per cent c.i. 1·08 to 1·94). After 5 years, aortic-related mortality was similar in the two groups, but cardiopulmonary mortality was higher after TEVAR. TEVAR was associated with more aortic-related reinterventions (23·1 versus 14·3 per cent; adjusted HR 1·70, 95 per cent c.i. 1·11 to 2·60). There were 141 procedures for ruptured thoracic aneurysm (97 TEVAR, 44 open), with TEVAR showing no significant advantage in terms of operative mortality.

CONCLUSION

In England, operative mortality for degenerative descending thoracic aneurysm was similar after either TEVAR or open repair. Patients who had TEVAR appeared to have a higher reintervention rate and worse long-term survival, possibly owing to cardiopulmonary morbidity and other selection bias.

Systematic review and meta-analysis of the growth and rupture rates of small abdominal aortic aneurysms: implications for surveillance intervals and their cost-effectiveness

BACKGROUND

Small abdominal aortic aneurysms (AAAs; 3.0-5.4 cm in diameter) are usually asymptomatic and managed by regular ultrasound surveillance until they grow to a diameter threshold (commonly 5.5 cm) at which surgical intervention is considered. The choice of appropriate surveillance intervals is governed by the growth and rupture rates of small AAAs, as well as their relative cost-effectiveness.

OBJECTIVES

The aim of this series of studies was to inform the evidence base for small AAA surveillance strategies. This was achieved by literature review, collation and analysis of individual patient data, a focus group and health economic modelling.

DATA SOURCES

We undertook systematic literature reviews of growth rates and rupture rates of small AAAs. The databases MEDLINE, EMBASE on OvidSP, Cochrane Central Register of Controlled Trials 2009 Issue 4, ClinicalTrials.gov, and controlled-trials.com were searched from inception up until the end of 2009. We also obtained individual data on 15,475 patients from 18 surveillance studies.

REVIEW METHODS

Systematic reviews of publications identified 15 studies providing small AAA growth rates, and 14 studies with small AAA rupture rates, up to December 2009 (later updated to September 2012). We developed statistical methods to analyse individual surveillance data, including the effects of patient characteristics, to inform the choice of surveillance intervals and provide inputs for health economic modelling. We updated an existing health economic model of AAA screening to address the cost-effectiveness of different surveillance intervals.

RESULTS

In the literature reviews, the mean growth rate was 2.3 mm/year and the reported rupture rates varied between 0 and 1.6 ruptures per 100 person-years. Growth rates increased markedly with aneurysm diameter, but insufficient detail was available to guide surveillance intervals. Based on individual surveillance data, for each 0.5-cm increase in AAA diameter, growth rates increased by about 0.5 mm/year and rupture rates doubled. To control the risk of exceeding 5.5 cm to below 10% in men, on average a 7-year surveillance interval is sufficient for a 3.0-cm aneurysm, whereas an 8-month interval is necessary for a 5.0-cm aneurysm. To control the risk of rupture to below 1%, the corresponding estimated surveillance intervals are 9 years and 17 months. Average growth rates were higher in smokers (by 0.35 mm/year) and lower in patients with diabetes (by 0.51 mm/year). Rupture rates were almost fourfold higher in women than men, doubled in current smokers and increased with higher blood pressure. Increasing the surveillance interval from 1 to 2 years for the smallest aneurysms (3.0-4.4 cm) decreased costs and led to a positive net benefit. For the larger aneurysms (4.5-5.4 cm), increasing surveillance intervals from 3 to 6 months led to equivalent cost-effectiveness.

LIMITATIONS

There were no clear reasons why the growth rates varied substantially between studies. Uniform diagnostic criteria for rupture were not available. The long-term cost-effectiveness results may be susceptible to the modelling assumptions made.

CONCLUSIONS

Surveillance intervals of several years are clinically acceptable for men with AAAs in the range 3.0-4.0 cm. Intervals of around 1 year are suitable for 4.0-4.9-cm AAAs, whereas intervals of 6 months would be acceptable for 5.0-5.4-cm AAAs. These intervals are longer than those currently employed in the UK AAA screening programmes. Lengthening surveillance intervals for the smallest aneurysms was also shown to be cost-effective. Future work should focus on optimising surveillance intervals for women, studying whether or not the threshold for surgery should depend on patient characteristics, evaluating the usefulness of surveillance for those with aortic diameters of 2.5-2.9 cm, and developing interventions that may reduce the growth or rupture rates of small AAAs.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Treatment decisions for descending thoracic aneurysm: preferences for thoracic endovascular aneurysm repair or surveillance in a discrete choice experiment

OBJECTIVE

To investigate and rank factors that influence endovascular treatment decisions by specialists for patients with descending thoracic aortic aneurysm (dTAA).

METHODS

Specialists completed a diagrammatic survey describing uncertainty about the benefit of thoracic endovascular aneurysm repair (TEVAR) for dTAA with respect to age, sex, and aneurysm diameter. Subsequently, a detailed discrete choice experiment was designed. Specialists were recruited and asked to indicate treatment their preference (TEVAR or surveillance) in 25 hypothetical cases of dTAA, with variable patient attributes: age, sex, American Society of Anesthesiologists (ASA) grade, aneurysm diameter, adequate landing zone distal to left subclavian artery (LSA), and length of aortic coverage. Data were analysed using multiple logistic regression.

RESULTS

The diagrammatic survey, based on 50 respondents, showed that uncertainty about the benefits of TEVAR was greatest for patients aged 80-85 years (up to 47% of respondents were "unsure") and that uncertainty increased with increasing aneurysm diameter (for an 80-year-old man, 7% were unsure at 5.5 cm and 33% were unsure at 7.0 cm). Seventy-one specialists (mainly from Europe and North America, 86% vascular surgeons and 98% working in units offering TEVAR) completed the discrete choice experiment. Preference for TEVAR increased greatly with enlarging diameter: adjusted odds ratios (OR) >5.5-6.0 cm = 15.8 (95% confidence interval [CI] 9.83-25.40); >6.0-6.5 cm = 393.0 (95% CI 202.00-766.00); >6.5-7.0 cm = 1829.0 (95% CI 400.00-4,181.00). TEVAR was less likely to be preferred in patients older than 75 years (>75-80 years OR 0.32, 95% CI 0.21-0.49; >80-85 years = 0.18, 95% CI 0.11-0.28); in women (OR 0.52, 95% CI 0.37-0.74); in patients classified as ASA grade 4 (OR 0.44, 95% CI 0.36-0.57); and in patients with aorta coverage >25 cm (OR 0.48, 95% CI 0.32-0.74). The proximal landing zone did not influence preference.

CONCLUSION

Specialists' preferences for endovascular repair of degenerative dTAA vary widely, and demonstrate clinical uncertainty, especially in octogenarians, and a reluctance to offer TEVAR to women. Aneurysm diameter dominates treatment preferences, but patient fitness and length of aortic coverage (>25 cm) also were influential, although the landing zone distal to LSA was not.

Vitamin D and cardiovascular disease

Vitamin D plays a classical hormonal role in skeletal health by regulating calcium and phosphorus metabolism. Vitamin D metabolites also have physiological functions in nonskeletal tissues, where local synthesis influences regulatory pathways via paracrine and autocrine mechanisms. The active metabolite of vitamin D, 1α,25-dihydroxyvitamin D, binds to the vitamin D receptor that regulates numerous genes involved in fundamental processes of potential relevance to cardiovascular disease, including cell proliferation and differentiation, apoptosis, oxidative stress, membrane transport, matrix homeostasis, and cell adhesion. Vitamin D receptors have been found in all the major cardiovascular cell types including cardiomyocytes, arterial wall cells, and immune cells. Experimental studies have established a role for vitamin D metabolites in pathways that are integral to cardiovascular function and disease, including inflammation, thrombosis, and the renin-angiotensin system. Clinical studies have generally demonstrated an independent association between vitamin D deficiency and various manifestations of degenerative cardiovascular disease including vascular calcification. However, the role of vitamin D supplementation in the management of cardiovascular disease remains to be established. This review summarizes the clinical studies showing associations between vitamin D status and cardiovascular disease and the experimental studies that explore the mechanistic basis for these associations.

Long-term cost-effectiveness analysis of endovascular versus open repair for abdominal aortic aneurysm based on four randomized clinical trials

Background

A number of published economic evaluations of elective endovascular aneurysm repair (EVAR) versus open repair for abdominal aortic aneurysm (AAA) have come to differing conclusions about whether EVAR is cost-effective. This paper reviews the current evidence base and presents up-to-date cost-effectiveness analyses in the light of results of four randomized clinical trials: EVAR-1, DREAM, OVER and ACE.

Methods

Markov models were used to estimate lifetime costs from a UK perspective and quality-adjusted life-years (QALYs) based on the results of each of the four trials. The outcomes included in the model were: procedure costs, surveillance costs, reintervention costs, health-related quality of life, aneurysm-related mortality and other-cause mortality. Alternative scenarios about complications, reinterventions and deaths beyond the trial were explored.

Results

Models based on the results of the EVAR-1, DREAM or ACE trials did not find EVAR to be cost-effective at thresholds used in the UK (up to £30 000 per QALY). EVAR seemed cost-effective according to models based on the OVER trial. These results seemed robust to alternative model scenarios about events beyond the trial intervals.

Conclusion

These analyses did not find that EVAR is cost-effective compared with open repair in the long term in trials conducted in European centres. EVAR did appear to be cost-effective based on the OVER trial, conducted in the USA. Caution must be exercised when transferring the results of economic evaluations from one country to another.

Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm

BACKGROUND

Single-centre series of the management of patients with ruptured abdominal aortic aneurysm (AAA) are usually too small to identify clinical factors that could improve patient outcomes.

METHODS

IMPROVE is a pragmatic, multicentre randomized clinical trial in which eligible patients with a clinical diagnosis of ruptured aneurysm were allocated to a strategy of endovascular aneurysm repair (EVAR) or to open repair. The influences of time and manner of hospital presentation, fluid volume status, type of anaesthesia, type of endovascular repair and time to aneurysm repair on 30-day mortality were investigated according to a prespecified plan, for the subgroup of patients with a proven diagnosis of ruptured or symptomatic AAA. Adjustment was made for potential confounding factors.

RESULTS

Some 558 of 613 randomized patients had a symptomatic or ruptured aneurysm: diagnostic accuracy was 91·0 per cent. Patients randomized outside routine working hours had higher operative mortality (adjusted odds ratio (OR) 1·47, 95 per cent confidence interval 1·00 to 2·17). Mortality rates after primary and secondary presentation were similar. Lowest systolic blood pressure was strongly and independently associated with 30-day mortality (51 per cent among those with pressure below 70 mmHg). Patients who received EVAR under local anaesthesia alone had greatly reduced 30-day mortality compared with those who had general anaesthesia (adjusted OR 0·27, 0·10 to 0·70).

CONCLUSION

These findings suggest that the outcome of ruptured AAA might be improved by wider use of local anaesthesia for EVAR and that a minimum blood pressure of 70 mmHg is too low a threshold for permissive hypotension.

Should the frequency of surveillance for small abdominal aortic aneurysms be reduced?

Different national screening programmes use a variety of surveillance intervals for patients identified with small abdominal aortic aneurysm. An individual patient meta-analysis of >15000 persons with small aneurysm has provided a strong scientific basis for safe surveillance frequency. In many screening programmes the number of surveillance visits for men could be reduced by up to half. The higher rate of aneurysm rupture in women leads to different recommendation for women.

Thoracic aortic aneurysms

Still uncertainty about the need for treatment

Incidence of descending aortic pathology and evaluation of the impact of thoracic endovascular aortic repair: a population-based study in England and Wales from 1999 to 2010

OBJECTIVES

To investigate population trends in thoracic aortic disease (dissections and aneurysms) in England and Wales, with focus on the impact of thoracic endovascular aortic repair on procedure numbers and age at repair.

MATERIALS AND METHODS

Routine hospital statistics of England and Wales provided admission, procedure and mortality data from 1999 to 2010. All data were age-standardised, reported per 100,000 population, by age bands (>50 years or 50-74 years versus 75+ years) and gender. Only patients 50+ years were included, to focus on degenerative disease.

RESULTS

Between 1999 and 2010 hospital admissions for total (ascending and descending) have risen steadily for thoracic aortic dissection (TAD) from 7.2 to 8.8 and thoracic aortic aneurysm (TAA) from 4.4 to 9.0, principally attributable to increased admissions in those 75+ years. Total mortality declined steadily over the same period, for TAD from 4.4 to 3.2 and for TAA from 10.4 to 7.5. Procedure rates have risen sharply, driven by the implementation of TEVAR from 2006, for type B dissection from 0.06 to 0.53 and for descending TAA from 0.76 to 1.89. All figures are per 100,000 population with P <0.005.

CONCLUSION

Improvements in case ascertainment may have contributed to the increase in hospital admissions. The increased application of TEVAR, particularly for dissections, is mainly in those above 75 years and has not yet translated into an accelerated survival benefit.

Explaining the decrease in mortality from abdominal aortic aneurysm rupture

BACKGROUND

A steady rise in mortality from abdominal aortic aneurysm (AAA) was reported in the 1980s and 1990 s, although this is now declining rapidly. Reasons for the recent decline in mortality from AAA rupture are investigated here.

METHODS

Routine statistics for mortality, hospital admissions and procedures in England and Wales were investigated. All data were age-standardized. Trends in smoking, hypertension and treatment for hypercholesterolaemia (statins), together with regression coefficients for mortality, were available from public sources for those aged at least 65 years. Deaths from ruptured AAA avoided in this age group were estimated by using the IMPACT equation: deaths avoided = (deaths in index year) × (risk factor decline) × β-coefficient.

RESULTS

From 1997, deaths from ruptured AAA have decreased sharply, almost twofold in men. Hospital admissions for elective AAA repair have increased modestly (from 40 to 45 per 100,000 population), attributable entirely to more procedures in those aged 75 years and over (P < 0.001). Admissions for ruptured AAA have declined from 18.6 to 13.5 per 100,000 population, across all ages, with the proportion offered and surviving emergency repair unchanged. From 1997, mortality from ruptured aneurysm in those aged at least 65 years has fallen from 65.9 to 44.6 per 100,000 population. An estimated 8-11 deaths per 100,000 population were avoided by a reduced prevalence of smoking and a similar number from an increase in the number of elective AAA repairs. Estimates for the effects of blood pressure and lipid control are uncertain.

CONCLUSION

The reduction in incidence of ruptured AAA since 1997 is attributable largely to changes in smoking prevalence and increases in elective AAA repair in those aged 75 years and over.

Meta-analysis of individual patient data to examine factors affecting growth and rupture of small abdominal aortic aneurysms

Background

Surveillance is a common management strategy for small abdominal aortic aneurysm (AAA) (3·0–5·4 cm in diameter). Individual characteristics, other than diameter, may influence aneurysm growth or rupture rates.

Methods

Individual data were collated from 15 475 people under follow-up for a small aneurysm in 18 studies. The influence of co-variables (including demographics, medical and drug history) on aneurysm growth and rupture rates (analysed using longitudinal random-effects modelling and survival analysis with adjustment for aneurysm diameter) were summarized in an individual patient meta-analysis.

Results

The mean aneurysm growth rate of 2·21 mm/year was independent of age and sex. Growth rate was increased in smokers (by 0·35 mm/year) and decreased in patients with diabetes (by 0·51 mm/year). Mean arterial pressure had no effect and antihypertensive or other cardioprotective medications had only small, non-significant effects on aneurysm growth, consistent with the observation that calendar year of enrolment was not associated with growth rate. Rupture rates were almost fourfold higher in women than men (P &lt; 0·001), were double in current smokers (P = 0·001) and increased with higher blood pressure (P = 0·001).

Conclusion

Follow-up schedules for individuals with a small AAA may need to consider diabetes and smoking, in addition to aneurysm diameter. The differing risk factors for growth and rupture suggest that a lower threshold for surgical intervention in women may be justified. No single drug used for cardiovascular risk reduction had a major effect on the growth or rupture of small aneurysms.

The management of ruptured abdominal aortic aneurysms: screening for abdominal aortic aneurysm and incidence of rupture

Twenty-five years have passed since the first randomised controlled trial began its recruitment for screening for abdominal aortic aneurysm (AAA) in men aged 65 and above. Since this and other randomised trials, all launched in the late 80s and 90s of the last century, the epidemiologic profile of abdominal aortic aneurysm may have changed. The trials reported an AAA prevalence in the range of 4-7% for men aged 65 years or more. AAA-related mortality was significantly improved by screening, and after 13 years, the largest trial showed a benefit for all-cause mortality. Screening also was shown to be cost-effective. Today, there are studies showing a substantial decrease of AAA prevalence to sometimes less than 2% in men aged ≥ 65 years and there is evidence that the incidence of ruptured aneurysm and mortality from AAA is also declining. This decline preceded the implementation of screening programmes but may be due to a change in risk factor management. The prevalence of smoking has decreased and there has been improvement in the control of hypertension and a rising use of statins for cardiovascular risk prevention. Additionally, there is a shift of the burden to the older age group of ≥ 75 years. Such radical changes may influence screening policy and it is worth reflecting on the optimum age of screening - it might be better to screen at ages >65 years - or rescreening 5 to 10 years after the first screen.

Incidence of cardiovascular events and death after open or endovascular repair of abdominal aortic aneurysm in the randomized EVAR trial 1

BACKGROUND

The aim was to compare rates of myocardial infarction, stroke and cardiovascular death in patients with a large abdominal aortic aneurysm who had endovascular (EVAR) or open repair to determine whether cardiovascular mortality explains the convergence in survival curves after these procedures.

METHODS

Between 1999 and 2004, 1252 patients were randomized to EVAR or open repair in the UK EVAR trial 1. All patients were followed for death, myocardial infarction or stroke until September 2009. Cox regression was used to compare cardiovascular events and deaths between the randomized groups during different time intervals.

RESULTS

Over 5 years of follow-up, a total of 187 first non-fatal or fatal cardiovascular events (98 myocardial infarctions and 89 strokes) and 256 cardiovascular deaths occurred. Although the endovascular group had a lower cardiovascular event rate than the open repair group (2·6 versus 3·2 per 100 person-years respectively) this was not statistically significant (adjusted hazard ratio (HR) 0·83, 95 per cent confidence interval 0·62 to 1·10; P = 0·199). Overall, there was little difference in cardiovascular mortality between the randomized groups (adjusted HR 1·06, 0·83 to 1·36; P = 0·638), but a non-significant excess of cardiovascular deaths was apparent in the endovascular group during the 6-24-month interval (adjusted HR 1·44, 0·79 to 2·62; P = 0·237).

CONCLUSION

Patients who had EVAR appeared to have a lower subsequent cardiovascular event rate during all time intervals. Cardiovascular mortality was similar between the two groups overall, but more cardiovascular deaths in the EVAR group appeared to contribute to the convergence in all-cause mortality during the first 2 years.

Systematic review and meta-analysis of growth rates of small abdominal aortic aneurysms

BACKGROUND

Small abdominal aortic aneurysms are usually asymptomatic and managed safely in ultrasound surveillance programmes until they grow to a diameter threshold where intervention is considered. The aim of this study was to synthesize systematically the published data on growth rates for small aneurysms to investigate the evidence basis for surveillance intervals.

METHODS

This was a systematic review of the literature published before January 2010, which identified 61 potentially eligible reports. Detailed review yielded 15 studies providing growth rates for aneurysms 3·0-5·5 cm in diameter (14 in millimetres per year, 1 as percentage change per year). These studies included 7630 people (predominantly men) enrolled during 1976-2005.

RESULTS

The pooled mean growth rate was 2·32 (95 per cent confidence interval 1·95 to 2·70) mm/year but there was very high heterogeneity between studies; the growth rate ranged from - 0·33 to + 3·95 mm/year. Six studies reported growth rates by 5-mm diameter bands, which showed the trend for growth rate to increase with aneurysm diameter. Simple methods to determine growth rate were associated with higher estimates. Meta-regression analysis showed that a 10-mm increase in aneurysm diameter was associated with a mean(s.e.m.) 1·62(0·20) mm/year increase in growth rate. Neither mean age nor percentage of women in each study had a significant effect. On average, a 3·5-cm aneurysm would take 6·2 years to reach 5·5 cm, whereas a 4·5-cm aneurysm would take only 2·3 years.

CONCLUSION

There was considerable variation in the reported growth rates of small aneurysms beyond that explained by aneurysm diameter. Fuller evidence on which to base surveillance intervals for patients in screening programmes requires a meta-analysis based on individual patient data.