Advice

The technologies

The technologies

Memokath‑028 (PNN Medical) is a prostatic stent used to relieve urethral obstruction caused by enlarged prostate glands. Memokath‑044 and Memokath‑045 (PNN Medical) are urethral stents. Memokath‑044 is used to relieve obstruction in the posterior (bulbar) part of the urethra, whereas Memokath‑045 is used to relieve obstruction of the anterior (penile) part of the urethra or at the bladder neck. Different versions of Memokath‑045 are available for use in the anterior urethra and at the bladder neck (PNN Medical). All 3 stents are available in several different lengths.

Memokath stents are made from a nickel-titanium alloy. This expands and becomes rigid when exposed to heat, and softens when cooled. Before insertion, the area to be stented (that is, the length of the obstruction) is measured with a cystoscope to determine the length of stent to be used. The stent is then inserted using the system provided (onto which it is pre-mounted). After insertion, stents are flushed with heated sterile fluid (saline or water, 55 ºC to 65ºC), which causes 1 (Memokath‑028 and Memokath‑044) or both (Memokath‑045) ends of the stent to expand, anchoring it in the appropriate position. Once expanded, the stent widens the urethral lumen which allows urine to flow freely.

Innovations

Memokath stents are 'thermo-expandable': that is, they change size and shape depending on temperature. They can be removed from the urethra at any point in the care pathway. They can also be inserted under local anaesthesia and are designed to provide a less invasive method for relieving urethral obstruction than surgery such as transurethral resection of the prostate (TURP) or urethroplasty. Surgery under general or regional anaesthesia is often not an option for people with urethral obstruction (Kimata 2015, Lee 2005, Papatsoris 2009). In addition, using Memokath stents may reduce the risk of urinary tract infection compared with catheterisation.

Other urethral stents, which may be used currently in the NHS but are not part of standard care, are designed to be permanently implanted. This encourages growth of urethral tissue in and around the stent (epithelialisation) to secure its position in the urethral wall. However, clinicians may wish to remove the stent if the urethral obstruction has been resolved, or because of complications. Although the Memokath stents are designed to stay in place for several years, if necessary they can be easily removed by using cold saline or water (less than 10ºC) to soften the alloy. This allows the stent to uncoil into a wire that can be removed with forceps.

For Memokath‑044 and Memokath‑045, stenting maintains urethral width for longer than urethral dilation or urethrotomy alone, meaning that fewer people may need repeated invasive surgery.

Current NHS pathway

The NICE guideline on the management of lower urinary tract symptoms in men recommends that standard care for obstruction because of an enlarged prostate is surgery such as TURP. The guideline recommends that if surgery is unsuitable or a person chooses not to have it, intermittent self-catheterisation or, as a last resort, long-term indwelling catheterisation should be considered. NICE has also produced medical technologies guidance on the UroLift system and TURis, both of which are recommended as treatment options for benign prostatic enlargement.

A number of treatment options are available to relieve obstructions in the anterior or posterior urethra, including urethral dilation, urethrotomy, clean intermittent self-catheterisation or urethroplasty. The choice of treatment is based on the length, cause and location of the obstruction, as well as patient preference, although urethroplasty is usually only done in people with obstructions longer than 3 cm. It may sometimes be used for obstructions shorter than 3 cm if there is an incomplete response to the first treatment (for example, urethrotomy; NHS England 2016; Santucci 2013).

NICE is aware of the following CE-marked devices that appear to fulfil a similar function to the Memokath stents:

  • UVENTA Urethral Stent (TaeWoong Medical, Memokath‑044)

  • Bulbar Urethral Stent (Allium Medical, Memokath‑044)

  • Triangular Prostatic Stent (Allium Medical, Memokath‑028).

NICE is developing medical technologies guidance on the Memokath-051 stent for ureteral obstruction.

Population, setting and intended user

All the Memokath stents are designed for use by urological surgeons in secondary care. Stent insertion can be done as a day case in an operating theatre. Table 1 describes the population for each of the Memokath stents.

Table 1 Use of Memokath stents

Memokath‑028

Men with enlarged prostate glands who would otherwise have surgery, self-catheterisation or long-term indwelling catheterisation.

Memokath‑044

Men with obstruction of the posterior urethra. The stent would be used in addition to urethral dilation and urethrotomy to maintain urethral width for longer periods.

Memokath‑045

Men with obstruction of the anterior urethra. The stent would be used in addition to urethral dilation and urethrotomy to maintain urethral width for longer periods.

People with obstruction of the bladder neck. This would generally be people with detrusor sphincter dyssynergia, which is an obstruction caused by damage to the nervous system (Stoffel 2016), usually as a result of spinal cord injury.

Costs

Technology costs

The costs of each Memokath stent (excluding VAT) are:

  • Memokath‑028: £945

  • Memokath‑044: £945

  • Memokath‑045: £1,150.

Cost does not vary by length of the stent.

For each stent, the company provides a number of consumables including a disposable insertion system and a cutter to remove the stent from its packaging (this keeps the stent sterile). Memokath‑044 comes with an extension tube, and Memokath-45 comes with 2 extension tubes and a 3-way stopcock. These consumables are included in the cost of the stent. Additional consumables and equipment are needed each time a Memokath stent is inserted, such as analgesic gel, lock syringes, sterile fluid, bottle warmers, thermometers, saline bags, measuring tape, drapes and a dilation kit. This equipment should be readily available in hospitals where Memokath is used.

An accompanying X-ray may be needed when inserting Memokath‑028 to confirm that the stent is in the correct position. An X-ray costs £30.26. Memokath stents can be removed during a day-case appointment. The national average cost of a day case is £847 per procedure (NHS reference costs 2015/16).

Costs of standard care

There are a number of options available to people with urethral obstruction. A common treatment is self- or indwelling catheterisation; the NICE guideline on the prevention and control of healthcare-associated infections notes that the mean cost of catheter use per patient ranges from £616 to £2,939 per year (updated from 2009/10 to 2015/16 prices using inflation indices), depending on the type of catheter. More minor procedures such as urethral dilation and urethrotomy are generally done as day cases in an inpatient setting, with a national average cost of £847 per procedure (NHS reference costs 2015/16).

More complicated surgical procedures such as TURP and urethroplasty are also treatment options. National average costs are £2,748 for TURP and £4,157 for urethroplasty (NHS reference costs 2015/16).

Resource consequences

According to the company, over 25 NHS trusts already use at least 1 of the Memokath stents. No practical difficulties or changes in infrastructure are expected from using Memokath stents.

Using Memokath stents may lead to increased resource use compared with catheterisation and minor surgeries such as urethral dilation, because the stents cost more. This may be offset if the stents could be used as true alternatives to prostatic surgery or urethroplasty. The stents may also reduce costs in terms of fewer urinary tract infections and a reduction in the need for other resources (for example, fewer catheters in cases where repeat catheterisation would normally be needed). However, there is currently no evidence to support this.