Memokath 051 Ureter stent for ureteric obstruction

The committee agreed that the new evidence supports the original guidance, suggesting that Memokath 051 Ureter stent had similar clinical success to other stents. But only 2 studies compared Memokath 051 with other stents. The clinical experts thought that, although there was new evidence, the evidence base has not improved substantially and the quality remained low. The committee concluded that, although there was new evidence reporting comparable clinical success rates with Memokath 051 and other stents, the comparative evidence remains limited.

The patient expert explained that people living with ureteric stents commonly reported pain, discomfort and urinary tract infections, and that the impact of stenting on people's quality of life is important. The clinical experts explained that Memokath 051 is a metal stent and usually well tolerated. They added that people tend to have fewer of the bladder irritation symptoms that are commonly associated with double‑J stents, so have a better quality of life. However, there is no new evidence on patient-reported outcomes or quality of life. The committee concluded that Memokath 051 could be a treatment option with improved patient experience, but more data on patient-reported outcomes and quality of life is needed.

The new evidence suggested that stent migration is the most common complication with Memokath 051 (as was the case in the original guidance). The committee was aware that the latest evidence suggests that Memokath 051 is more likely to move than other types of stents. But clinical experts explained that this may have been a result of differences in patient selection, and they also explained that stent migration does not necessarily lead to complications because the migration may be caused by changes in the ureteric obstruction itself. Other possible reasons for stent migration include stents placed too close to the pelvi-ureteric junction, using a stent that is too long, or using a single cone Memokath 051 stent, which is more likely to migrate than a double cone stent. The committee heard from the clinical experts that migration rates may be reduced with Memokath 051 by selecting patients carefully (see section 4.7), and possibly by a move to using the double cone stent instead of single cone.

No new equality issues were identified during the guidance update development. Some ureteric obstructions are caused by tumours, and everyone with cancer is protected under the Equality Act 2010 from the point of diagnosis. People with ureteric strictures caused by tumours may benefit from having Memokath 051 available as an alternative to double‑J stents. This is because it may be associated with fewer replacement procedures and reduced adverse events, which would reduce their overall number of appointments and improve their quality of life as they undergo cancer treatments, or make them more comfortable and have more time out of hospital if they have a limited life expectancy. Memokath 051 may also provide an alternative treatment for people with ureteric strictures who cannot tolerate conventional stents or for whom they have failed, who would otherwise be nephrostomy-dependent and may be disabled under the Equality Act 2010.

Clinical and patient experts explained that most people who had stent procedures knew little about what kind of stent they were having. The clinical experts explained that stent choice often relies on the assessment of urethral obstruction during a stent procedure in the surgical suite. They agreed that a best-case scenario would be explaining treatment options and associated risks to a person before placement, then giving them information about the treatment afterwards, including what stent was used and possible adverse events. The committee concluded that more information should be given to people to explain their care.

The clinical experts explained that Memokath 051 is currently used in some NHS trusts. The committee noted that some new published evidence for Memokath 051 is from studies that were done in the UK. One of the clinical experts involved in 1 of the UK studies (Forster et al. 2021) explained that a wide range of people with benign and malignant ureteric obstruction was included in the study, and its inclusion criteria for Memokath 051 were more relaxed than clinical practice. Therefore, people included in the retrospective analysis may be different from those who would be selected for Memokath 051 in clinical practice. The committee concluded that the new evidence is limited in the generalisability to clinical practice across sites in the UK because of the variability in patient selection.

The clinical experts said that different treatment options, including Memokath 051, are available in the NHS for people with ureteric obstruction. They considered that treatments need to be offered to people on an individual basis, guided by clinical assessment of individual circumstances. Important factors to consider include the cause of the obstruction and its length and location. Clinicians should also take into account the person's preference. For people with malignant ureteric obstruction, quality of life is often the most important factor in determining what treatment will be needed. Memokath 051's advantages over some other treatments available for ureteric obstruction in the NHS are that it is a less invasive procedure with no need for hospital stay, and fewer stent replacements are needed. For people with benign ureteric obstruction, Memokath 051 is an option if they cannot have, or prefer not to have, open surgical procedures such as reconstructive surgery. The clinical experts said that Memokath 051 should not be used in people with bladder cancer or bladder stones, or in people with pelvi-ureteric junction obstruction because of an increased risk of stent migration. It concluded that careful patient selection for Memokath 051 is important when treating ureteric obstruction.

The clinical experts said that people are monitored after stent insertion, but the way they are monitored varies. For instance, changes in the ureteric obstruction or stent position can be detected using different imaging examinations such as ultrasound or X‑ray. Using an X‑ray and an ultrasound scan together is considered the best way to detect stent migration. The committee concluded that regular follow-up visits are needed after Memokath 051 is inserted to monitor stent positioning.

The committee understood that the original cost model was relevant to the decision problem because its model structure and key assumptions remained valid. The external assessment group (EAG) updated the clinical parameters, including the cost of Memokath 051 and comparators to reflect changes in the risk of stent replacement and adverse events. Its updated base case showed that Memokath 051 remained cost saving compared with Allium, double‑J stents, Resonance and UVENTA over 5 years (see section 3.16). But using Memokath 051 is likely to incur an additional cost of £1,321 per person over 5 years compared with reconstructive surgery.

The committee considered that the cost case remains uncertain because of the lack of good quality evidence. The risk of stent replacement was 1 of the key drivers of the estimated cost savings with Memokath 051 compared with other stents. The analysis was based on an assumption that the same stent would be used for replacement. The clinical experts advised that, in clinical practice, people would not necessarily have the same brand of stent for replacement because people's conditions may change and Memokath 051 may no longer be suitable for them. There was limited data on stent replacement, and this introduced some uncertainty in the cost case between Memokath 051 and other stents.

The EAG's sensitivity analyses also identified other cost drivers including the length of time the stent is in place, replacement cost and follow-up costs. Memokath 051 remained cost saving in most of the scenarios compared with double‑J, UVENTA, Allium and Resonance but would be cost incurring compared with reconstructive surgery. The committee noted these were one-way sensitivity analyses, which may not fully address uncertainties in the cost model. It concluded that the cost case for Memokath 051 remained uncertain because of the limited evidence base.

Given the limited evidence available, the original guidance committee noted that it would be beneficial to routinely collect data on all ureteric stent placement procedures. This was ideally in collaboration with a national professional society such as the British Association of Urological Surgeons. Clinical experts confirmed that an NHS registry for stent procedures has not been set up since the original guidance, and the evidence base remains limited with no prospective data available. The committee for this guidance update considered it important to further emphasise the need for collecting data using a national database or clinical registry on ureteric stent procedures. The prospective data collection should cover information about patient selection, choice of stent placement procedure and stent used, and adverse events such as stent migration and encrustation rates. It concluded that this should form part of its recommendations in section 1 of the guidance, and agreed that such data collection should be used to help inform the most appropriate patient population for Memokath 051.