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Point-of-Care Testing for Peritoneal Dialysis Patients

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Following the recent CE-mark approval of a point-of-care device, patients on peritoneal dialysis are now able to test for infection in their own homes. This could lead to faster diagnosis and treatment for patients where infection is detected, but also help to reduce unnecessary visits to healthcare providers and the inappropriate use of antibiotics. 

We spoke to Barbara Fallowfield, Commercial Manager, Mologic, to learn more about the test, the benefits it can offer patients, and the role that point-of-care tests may play in the future of healthcare.

Can you tell us a little about peritoneal dialysis and peritonitis?

Peritoneal dialysis represents one way to manage end-stage renal disease that offers greater patient mobility and independence compared with haemodialysis, as well as being more gentle to residual kidney function in early stage disease. Peritoneal dialysis usage around the world is increasing slowly driven by the benefits of lower cost, increased patient mobility, and the ability to continue in the workforce, but hampered by a lack of sufficient numbers of trained staff, clinical assumptions, and concerns about risk of infection. 

PD requires the infusion of a sugar solution into the peritoneal cavity of a patient, where it dwells for a period of time, usually up to 4 hours. During this time the metabolic toxins in the blood diffuse passively into the dialysis fluid which is then drained off. Infusion of the bag contents is achieved through the surgical insertion of a catheter that crosses into the peritoneal cavity. Unfortunately this catheter can also be the Achilles heel of the treatment as it requires the patient, or their carer, to be highly proficient in hygiene techniques to ensure an infection doesn’t compromise the line or infect the bag contents. Infections can lead to the need for emergency treatment with antibiotics, replacement of the catheter, and potentially causes peritoneal lining damage or scarring that may prevent the long-term use of this treatment.

Peritonitis is a leading cause of patients transferring to more expensive haemodialysis. Rates of infection vary greatly from country to country, and sometimes even within countries, but in the UK, for many established patients, infections occur around once every 18-24 months of treatment. For some people however, infection is a recurring event.

What are the limitations of current methods to test for infection?

The current method of diagnosis is for patients to check the waste bag for cloudiness. If a cloudy bag is observed, they are then advised to visit their renal clinic (or A&E Dept if outside normal hours) where the patient is examined and the bag sent to the laboratory where a white blood cell count will be performed, and a sample will also be cultured. A white cell count can take anything from 30 minutes to 4 hours before it’s available in the clinic, so the patient is often put on antibiotics as a precautionary measure. Once a course of antibiotics has been started, it is usually continued even if the culture result is negative (and this would normally take 2-3 days).

Can you tell us about PERiPLEX® and some of the advantages it offers patients?

PERiPLEX has been designed using the same lateral flow technology used in home-use pregnancy tests, so it’s very simple to use with results being determined by the presence or absence of either of two test lines. The barrel of the sample device is designed to attach to the outlet port of the waste dialysate bag, with a concealed needle included in it which pierces the septum of the port. After 5-10 seconds, enough fluid has entered the device via the needle, so the device is then detached and laid flat for 5 minutes. After 5 minutes, a visual check is made for the presence of any pink lines. There should always be one line showing which is the control line – this provides a procedural check that the test has been run correctly ie that enough fluid has been added. If any additional lines are also present, this means that the test is positive and the patient should seek medical assistance.

The test offers patients the following advantages:

- For patients just starting on PD, it gives them reassurance that they are doing all of their hygiene procedures correctly ie a negative test with no other symptoms means all is well.

- For patients who are restarting PD following an episode of peritonitis, the test gives them reassurance in a similar way. If they have any worries about feeling unwell they can carry out a test at home rather than having to go into the clinic.

- Some patients will have a ‘trigger’ event which they fear may set off an episode of peritonitis eg a hygiene error or exposure to something, and in this instance being able to do a test daily for a couple of days will give them reassurance that all is well (or of course let them know if it’s not).

- Not all patients have PD treatment on a daily basis, and for these patients their waste bag is often cloudy on the first treatment after the rest day for reasons other than infection. The ability to do a test at home for these patients means that they may be able to avoid potentially wasting time by going into a clinic for leucocyte testing, culture etc, and may also mean the avoidance of potential overuse of antibiotics which can be given to these patients if seen by less experienced doctors.

- For any patient living remotely, the test can lead to faster treatment if a positive result is obtained and the patient has antibiotics available at home. Likewise, it can avoid an unnecessary long trip in to hospital if the result is negative and the patient has no other symptoms.

- If the test is used in a clinic setting, the clinic team can have a test result available before the white cell count comes back from the laboratory.

Further clinical studies are still required which we hope will demonstrate that the test will not only confirm the presence of infection, but that it will provide early warning before bag cloudiness is evident.  

PERiPLEX® recently received CE-mark approval, what hurdles had to be overcome along the path to achieving this?

As with all of our products which are either CE-marked or in development, the biggest hurdle has been access to clinical samples. Given the relatively low incidence of peritonitis in these patients, it has been a particular difficulty for this product. This was the first Mologic product to be CE-marked, so there was a lot to be learned about the regulatory requirements, and as this product is for home use these are more exacting than for products designed for professional use.

How important do you see point-of-care devices becoming in the future of healthcare? What factors need to be considered when developing these devices compared to laboratory based tests?

There is a global trend towards keeping patients out of hospital as much as possible, with the use of point-of-care tests for both home use and primary care professional use absolutely key to enabling this. Earlier diagnosis leads to earlier correct treatment, which should mean fewer complications so not only are patient outcomes better, but there should also be significant cost savings.

When developing devices like this for home use, it’s vital that the end user ie the patient, is involved to provide their input. Any device for home use has to be easy to use for the patient otherwise they just won’t use it, and the results also have to be easy to interpret. Patients know what their problems are which might not even occur to someone not in their situation. The instructions for use also have to be extremely clear, and not assume any prior knowledge or experience, whereas when developing devices for laboratory use, it is assumed that a certain level of training is available.  

Barbara Fallowfield was speaking to Anna MacDonald, Editor for Technology Networks.