Abdominal Aorta Aneurysm Screening

Collection summary

Background

Abdominal aortic aneurysm (AAA) is a pathological focal dilatation of the abdominal stem artery. AAA rupture is a dramatic emergency condition with a high risk of death.

Although it varies across European countries, the percentage of men at high risk of AAA has been increasing steadily over the last 20 years. Screening programmes for AAA have thus been considered as a potentially useful healthcare approach/intervention in European countries, even if in most countries no systematic nationwide screening programme has yet been implemented.

Screening programmes for AAA are used to identify individuals at a high risk of AAA rupture. Those identified are offered preventive surgery to reduce their individual risk of the negative consequences of a spontaneous rupture. For smaller aneurysms (3.0–3.9 cm) with a lower risk of rupture, medical therapy and watchful waiting is recommended while for medium-sized aneurysms (4.0–5.4 cm) elective surgery is indicated. In AAAs sized 5.5 cm or more in diameter the cut-off point of repair is reached. Whether to use an endovascular or an open surgical approach should be decided on an individual basis. Open surgery is indicated for patients with a low preoperative risk (younger patients). Endovascular surgery is indicated in patients with favourable anatomy and who are at high surgical risk.

Results

Safety of the technology (SAF)

AAA screening programmes can cause harm to the screened subjects due to the expected increase in the number of detected AAAs (increased incidence) and consequently in the number of surgical interventions to repair intact or non-ruptured AAAs suitable for repair. There are serious consequences in terms of mortality and morbidity, but also psychological effects related to a detected AAA. In addition, unnecessary stress may be engendered by false-positive findings using AAA screening, but literature is scarce.

Effectiveness of the technology (EFF)

Evidence from the literature indicates that AAA screening is beneficial in men over 65 years of age, as it reduces AAA-related mortality by nearly half in the mid- and long-term. In contrast to men, there are no reliable clinical data showing that women benefit from AAA screening.

AAA screening results in a decrease of emergency operations for ruptured AAA, which is counterbalanced by an increase in elective AAA surgery.

There is a need for further research in the area of screening intervals, risk-adjusted repeat screening, and training of sonographers for a better understanding of the effects of this technology.

Costs, economic evaluation of the technology (ECO)

The primary limitation of economic evaluation is the limited transferability of results from one setting to another and difficulty in combining the results in a reliable manner. A full cost-effectiveness analysis, based on data from the Finnish healthcare setting was produced, but not tested in different settings. Results of the cost-effectiveness of AAA screening are not directly transferable to other healthcare systems.

The majority of the available evidence, as well as our present evaluation, suggests that one-time ultrasound screening for AAA of 65-year-old men and women is cost-effective compared with a situation where no AAA screening is offered.

Ethical aspects of the technology (ETH)

There is high variability between healthcare systems; this variability reflects different cultural approaches and values in the design of healthcare. So the analysis of the ethical aspects informs only which questions should be answered and proposes how to do this in the local context. The main issue is that the points of view of different stakeholders are important. To balance these interests a combination of methodologies is needed.

Organisational aspects of the technology (ORG)

As only a few countries have a national systematic population-based AAA screening programme, most of the information in the analysis of organisational aspects comes from the UK setting. All organisational aspects (concerning healthcare systems’ staff and funding; demographic and geographic distribution of potential screening subjects) are more or less country specific. So the current overview can be used as a starting point for further research on the organisational impact of screening programmes.

Social aspects of the technology (SOC)

It is not possible to determine with certainty whether screening for AAA affects health-related quality of life among participants. Among those detected with a small AAA there are experiences of both limitations in daily life and distress as well as worries about an operation. Patient information in relation to AAA is limited, insufficient and difficult to understand. Though attendance rates for AAA screening are high, there are obstacles to participation among those at higher risk of AAA.

Legal aspects of the technology (LEG)

AAA screening via abdominal ultrasound is almost free of physical harm, discomfort or pain. The exceptions are the psychological aspect in the case of false-positive results or rupture in the case of false-negative results. Several pieces of legislation secure the right of access to (best) healthcare at the European Union (EU) level, and there are laws on appropriate counselling and information to be given to the user or patient.

Closing Remarks

The Core Model is not intended to provide a cookbook solution to all problems but to suggest a way in which information can be assembled and structured, and to facilitate its local adaptation. The information is assembled around the nine domains, each with several result cards in which questions and possible answers are reported.

The reasons for having a standardised but flexible content and layout are rooted in the way HTA is conducted in the EU and in the philosophy of the first EUnetHTA Joint Action (JA1) production experiment.

HTA is a complex multidisciplinary activity addressing a very complex reality – that of healthcare. Uniformly standardised evidence-based methods of conducting assessments for each domain do not exist (Corio M, Paone S, Ferroni E, Meier H, Jefferson TO, Cerbo M. Agenas – Systematic review of the methodological instruments used in Health Technology Assessment. Rome, July 2011.)). There are sometimes variations across and within Member States in how things are done and which aspects of the evaluation are privileged. This is especially so for the “softer” domains such as the ethical and social domains.

This test represents a useful lesson for methodological development in EUnetHTA Joint Action 2.

Collection methodology

Objective

To produce a Core Health Technology Assessment (HTA) assessing the effects of abdominal aortic aneurysm (AAA) screening based on the EUnetHTA Core Model and working within the Collaborative Model 2 (COLMOD 2) organisational framework.

Methods

The work was based on the HTA Core Model on screening technologies, which was developed during the EUnetHTA Joint Action 1 (JA1).

The first phase was the selection of the technology to be assessed using the Core Model; this phase was carried out through a three-step process that included surveys and questionnaires to Work Plan 4 (WP4) partners by email. At the same time, the Collaborative Model to be used in this Core HTA was chosen by WP4 Partners.

Then there was the check of Partners’ availability to assume responsibility, as an institution, to take the lead in one of the nine evaluation domains. At the same time, the nine domain teams were built-up in accordance with partners’ preferences and some general guidelines (i.e.: “each WP4/B Associated partner AP should be involved in at least one domain, indicating its interest for at least one domain”)

Finally the specific work plan was shared, according with the general WP4 3-years work plan and objectives. This specific work plan included the phases scheduled in the “HTA Core Model Handbook” (Production of Core HTAs and structured HTA information).

An editorial team was set up for discussion and major decisions on basic principles and solutions related to the content of core HTA .The editorial team was chaired by Tom Jefferson (Agenas),vice-chaired by Katrine B. Frønsdal (NOKC) and composed of all the primary investigators of the domains.

To allow collaboration between partners a draft protocol for Core Model use was agreed by the researchers involved. The research questions for each of the nine domains of the Core Model were formulated and the corresponding relevant assessment elements (AEs) were selected.

Overlaps between the domains were identified and assigned exclusively to one domain, by mutual agreement.

The research strategy was carried out by one of the domain team, collecting input from the others.

Evidence from published and manufacturer sources was identified, retrieved, assessed, and included according to pre-specified criteria, and summarised to answer each AE. Each domain assessment was made by a single agency (COLMOD2); researchers from different WP4 Partners reviewed and commented on the Core HTA.

Introduction to collection

This brief document provides background information on the preparation and development of the Core HTA on AAA screening. The core HTA document was produced during the course of the first EUnetHTA Joint Action (JA1) 2010-2012.

The idea behind EUnetHTA’s Core Model is to provide a framework for structuring relevant HTA information while at the same time facilitating local use and adaptation of the information or guiding its production.

The Model is based on nine dimensions or “domains” of evaluation:

1. Health Problem and Current Use of the Technology (CUR)
2. Description and technical characteristics of technology (TEC)
3. Safety (SAF)
4. Effectiveness (EFF)
5. Costs and economic evaluation (ECO)
6. Ethical analysis (ETH)
7. Organisational aspects (ORG)
8. Social aspects (SOC)
9. Legal aspects  (LEG)

The Core Model application on screening was tested by assessing the effects of AAA screening, by producing a Core HTA structured in the nine documents that follow, one for each domain.

The AAA Core HTA was prepared using an experimental Collaborative Model (COLMOD) - so called COLMOD 2 - in which one of the national or sub-national HTA participating agencies took responsibility for the production of each domain. The experimental organisational model added an element of challenge but probably helped to forge strong links across participants.

In the next few months an intensive validation programme including interviews and consultations will elicit comments and feedback both from those who contributed to the Core HTA and from those who read it for the first time. This validation plan includes an internal audit within the Work Package 4 during which each partner will validate parts of the Core HTA they did not produce themselves and the Core HTA production process (collaborative models, on-line tool, etc.).

At the same time, as scheduled in the 3-year work plan, the Core HTA will be sent to the Stakeholder Advisory Group (SAG) for feedback before the final Public Consultation, during which the Core HTA will be made available.

The results from the Validation and SAG consultation should provide useful information to improve the product, supporting us in amending the Core HTA.

The following agencies contributed to the preparation of the document:

• AAZ - Croatia
• AETSA - Spain
• Agenas - Italy
• AHTAPol - Poland
• Central Denmark - Denmark
• GÖG - Austria
• HVB - Austria
• IQWiQ - Germany
• ISCIII-AETS - Spain
• Laziosanità - Italy
• LBI-HTA - Austria
• NICE – United Kingdom
• NOKC - Norway
• SDU/CAST - Denmark
• SNHTA - Switzerland
• THL - Finland
• UTA - Estonia

Scope