Little evidence of safety in aneurysm treatment with new implants

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New implants to treat aneurysms in the brain are regularly reported in scientific articles as safe and effective, while the evidence for this is lacking. This is the conclusion of researchers from Erasmus MC, among others, in a study published in JAMA Network Open. They analyzed more than 1356 international studies involving more than 411,000 patients.

In the Netherlands, about a thousand patients suffer a cerebral hemorrhage due to an aneurysm every year. Also, two to three hundred people are treated before the aneurysm has burst. Treatment can be with surgery or endovascular. In recent years, many new devices have become available for the treatment of these aneurysms. Neurosurgeon Victor Volovici (Erasmus MC), first author of the study, says that although the safety and effectiveness of these ‘devices’ are mentioned ‘as a mantra’ in almost all publications, ‘whether they are also scientifically substantiated was a matter for us. very question’. The answer must be negative after analysis of the included studies. Less than 2 percent of these contained a description of what was understood by safety and effectiveness. Only one (!) study provided a threshold value below which the investigated technique would be considered unsafe. ‘Safety and effectiveness have become empty terms’, notes co-author and neurointerventional radiologist Pieter Jan van Doormaal (Erasmus MC).

‘The quality of the studies is poor,’ says Volovici. ‘In 80 percent, no control group was used to compare the results of the new implant. There is often no difference in complications, or even mortality, between studies that conclude something is safe and those that say it is not. Those who are not methodologists or epidemiologists might mistakenly think that everything is fine.’

The conclusion must therefore be that something goes wrong in the acceptance of these articles and thus in the peer review process. Volovici et al. have not investigated what that is exactly. He can only speculate: ‘Perhaps the peer review process is not always ‘double-blind’ (ie the reviewer knows the researchers, ed.) or methodologists are not always involved. Peer review is also under severe time pressure: I receive ten to fifteen requests per week. That pressure can promote laziness. And there may be bias on the part of the reviewer: he may know the new device, use it and have good experience with it.’ The remedy, according to Volovici: ‘Physicians, patient associations and the industry must jointly say: from now on we will only conduct studies with sufficient patients from several hospitals and with a good comparison group that represents the current standard treatment.’

The new implants have come onto the market as a successor to the two treatments for which there is good evidence: surgery through the skull to close the aneurysm (clipping) or filling of the aneurysm with platinum IUDs through a blood vessel in the groin (coiling). ). The goal is always: occlusion of the aneurysm. In recent years, the industry has developed new tools for this treatment, such as WEB devices and flow diverting stents. Van Doormaal: ‘These devices have a niche application; you use them when there are no other endovascular options. For example, some aneurysms cannot be coiled properly because the neck is too wide: a flow diverting stent can offer a solution.’

The lack of solid evidence does not automatically mean that the new drugs are not safe, emphasize Volovici and Van Doormaal. ‘We have now reached a high level in aneurysm treatment,’ says Volovici. ‘We operate much better than in the 1990s. In order to be able to demonstrate an even higher level incrementally thanks to the use of these new devices, you need a lot of patients. But that does not release you from the obligation to do proper research; it would be good if we could prove that the new drugs are at least no worse in terms of safety and effectiveness.’

Van Doormaal: ‘You have to remain critical, you shouldn’t use them blindly. This requires a multidisciplinary approach. You can then determine the best intervention for the patient based on the situation. You can already see a kind of proliferation in the United States, because the stents are super easy to place. In some centers the bulk of the treatments is done with flow diverting stents and no longer with clipping or coiling. That in itself is not necessarily a bad thing, but it is precisely with such a very broad deployment that you have to know for sure whether they are safe and effective.’

Patients who have been treated with such a new implant in the Netherlands need not worry, says Volovici. ‘These patients are checked regularly and we have an extensive system of quality checks in Europe before a new medical device is launched.’

Incidentally, the treatment of incidentally found aneurysms in the Netherlands is quite conservative, Van Doormaal emphasizes. The Phases score (developed in Utrecht in 2014) is used here, with which a five-year rupture risk can be calculated that can be related to the complication risk. The bulk of incidentally found aneurysms are not treated on this basis in the Netherlands – unlike in the United States. Of course, the patient also has a voice, and if necessary, the interventional radiologist and neurosurgeon speak with him or her at Erasmus MC. For example, about the question: does he/she want surgery, which is more risky, but the aneurysm is gone; or does he or she want endovascular treatment – less risky, but with a slightly higher chance of the problem coming back? Volovici: ‘And sometimes the risks are the same, but the patient feels that surgery is more difficult than treatment via the groin.’

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