Endovascular treatment of abdominal aortic aneurysm: a NICE U-turn

In 2001, Collin and Murie1 challenged the concept of endovascular repair (EVAR) for abdominal aortic aneurysm (AAA) in an editorial that remains controversial even now. Around 18 months ago, two guideline documents on the management of AAA were released: one by the European Society for Vascular and Endovascular Surgery (ESVS)2 and one in draft by the UK National Institute for Health and Care Excellence (NICE)3 (Fig. 1). The ESVS document is a clinical review, and acknowledges the way that EVAR has become the treatment of choice for many people worldwide. EVAR offers minimally invasive treatment which can be done under local or regional anaesthesia, reducing postoperative pain, hospital stay and 30-day mortality compared with conventional open aortic aneurysm repair (OAR)4. It has extended the options available for patients with juxtarenal and suprarenal aortic aneurysms, with use of branched and fenestrated devices5. There is also some evidence of advantage in emergency EVAR for patients with ruptured AAA6. In 2018, NICE had a somewhat different view, based largely on a formal clinical and cost-effectiveness analysis of RCTs comparing EVAR with OAR3. It concluded EVAR is not cost-effective, even if the devices, which are currently expensive, could be produced at low cost. This should not have come as a surprise to vascular surgeons, because a previously published cost-effectiveness analysis of EVAR also found it to be less cost-effective than open repair7. The main reason seems to be the ongoing cost of interventions for stent maintenance after insertion, which is not applicable to OAR. There is also a risk of late rupture after EVAR, not seen after OAR8. NICE draft guidelines suggested that patients with a large intact AAA should not be offered EVAR if they are fit enough for OAR. NICE also suggested that those who are not suitable for OAR, because of their anaesthetic or medical condition, should not be offered EVAR. This was perhaps the inevitable conclusion of an objective analysis of the EVAR 2 trial, which has been an elephant in the room of vascular surgery for over a decade9. In patients unfit for OAR (the EVAR 2 cohort), EVAR is pretty well tolerated and can minimize the risk of death from subsequent AAA rupture. However, it does not prolong life, and almost all patients in both groups of the EVAR 2 trial died within a decade9. Infrarenal abdominal aortic aneurysm The draft NICE guidelines were inevitably controversial among vascular surgeons and interventional radiologists, who have espoused the endovascular revolution for treatment of both aortic and peripheral artery diseases. Enormous effort and resource have been poured into training the next generation of vascular specialists with endovascular skills. An industry of devices has grown up around these endovascular interventions, which have increased the costs of many allied vascular treatments. It was argued NICE relied on old RCTs that studied the generation of EVAR devices of a decade ago (though this was not borne out by NICE's technical analyses). Modern devices may be safer and more effective, and with lower reintervention rates. Reducing the costs of lifelong surveillance with modern schedules should also improve cost-effectiveness10,11. Yet, even now, some new devices launched with enthusiasm only recently appear to have problems and seem unlikely to endure12. In March 2020, NICE published its final version of the guidelines for management of AAA13. It has done a U-turn, and now accepts that EVAR is a reasonable option for the management of AAA under certain conditions: hostile abdomen, medical problems, etc. However, the guidelines also seem to introduce an element of patient choice, such that EVAR may be considered for patients who have anaesthetic risks and/or medical co-morbidities that would contraindicate open surgical repair. This extraordinary decision appears to fly in the face of NICE's own technical and scientific analysis, and the reasons are not explained. The Guideline Development Committee has released a strongly worded statement distancing itself from the revised conclusions, which were apparently not discussed with the Committee, or its Chair14. Although there was a strong reaction to the draft guidelines from vascular surgeons around the world15, NICE has never before succumbed to peer pressure, and the only logical conclusion is that it has yielded to pressure from stakeholders who stood to lose if the number of EVARs diminished. Yet the original analysis done by NICE still stands unchallenged, and the resulting deliberations among vascular surgeons are still relevant. For example, it is well known that complications and reinterventions are more common when the EVAR device is inserted outside ideal anatomical conditions. If the manufacturer's instructions for use (IFU) is followed strictly, the risk of reintervention is much lower, but only two-thirds of infrarenal AAAs fall into this category, and one-third would therefore be denied EVAR. It is often argued that for an individual patient the risk of inserting a stent off IFU may be better than a high-risk open repair. Manufacturers of stent grafts are unlikely to agree, but it could be argued that they bear some responsibility, having observed so many of their stents inserted under suboptimal conditions. If the guidelines simply make vascular surgeons think more carefully before using an EVAR device off IFU, they will have been worthwhile. Complex EVAR for juxtarenal and suprarenal AAAs is an option for some patients. Good studies on fenestrated and branched endovascular interventions are few, and generally only reported by enthusiasts5. The intervention is complex and considerably more expensive even than EVAR, and there are few data on the outcomes for all-comers. The ESVS guidelines endorse complex EVAR for juxtarenal and suprarenal aortic aneurysms, whereas NICE was originally clear: endovascular treatment must not be offered for intact aneurysms outside the confines of an RCT, and then only in patients fit for open surgery. The final version of the guidelines has a softer attitude. Complex EVAR may be considered in patients fit for open repair if the risks and benefits have been discussed with the patient. It may even be considered in patients unfit for open repair as long as the uncertainties around outcome have been discussed. Patients may trade some risk of adverse outcome for improved recovery16. NICE's previous recommendation of a well conducted study of clinical and cost-effectiveness of treatments for complex aneurysms remains fundamental, and the opportunity for the vascular community to encourage these studies should not be lost by NICE's change of heart. The UK has been at the forefront of screening for AAA in men, and national programmes have been running for 5 years17. The NICE guidelines endorse the ultrasound methodology used in the UK screening programmes and also their revised (prolonged) surveillance intervals. As the inner-to-inner measurement used in the National Health Service programmes records aortic diameter around 0.5 cm smaller than on CT, this may prompt a reconsideration of thresholds for treatment, if based on CT measurement. Relaxation of the draft NICE guidelines will be welcomed by many vascular surgeons, but the technical cost-effectiveness analyses cannot be ignored. All countries wish to see patients having access to treatments that are cost-effective. Some vascular surgeons may be accused of adopting EVAR too enthusiastically and uncritically, pushing the boundaries beyond the technical capabilities of the devices. The rise in the number of AAAs treated has largely been in the elderly, those who stand to gain least. A measured response to the evidence would be to be more cautious in multidisciplinary meetings about patients at the extremes of age and fitness, and also to support enthusiasm to conduct (or even repeat) RCTs with current devices. Partnership with the device manufacturers will be needed to fund and complete these trials, which are also in their interests. Finally, it remains to be seen how badly damaged NICE's reputation will be by this incredible volte face. Although UK vascular surgeons and the Vascular Society of Great Britain and Ireland may feel that their pressure on NICE has encouraged this decision, from the outside, the only logical explanation for this change is external pressure. NICE's reputation for firm and fair decision-making, and its transparent processes may be tainted. An explanation for its revised decision should be forthcoming, and NICE processes for examining new technology should be reviewed18. Producing guidelines is a responsible task, with no excuse for complacent totalitarianism. This has been a painful process for vascular surgeons, but has meant they have reassessed decision-making for intervention on AAA, and already there has been a reduction in the number of people treated with EVAR where the benefit was questionable. The revised NICE guidelines are generally aligned with those from the ESVS, which will benefit patients with an AAA. The authors declare no conflict of interest.