HTA Core Model^® Online

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.