Information for Participants

We are doing this study to find out whether a drug called metformin can slow down the rate at which kidney disease progresses in people with Autosomal Dominant Polycystic Kidney Disease (ADPKD).

Metformin is not a new medicine. It is currently used to treat patients with diabetes.

If you do not want to take part that’s OK. Your decision will not affect the care you receive.

If you take part, you are free to withdraw at any time without giving a reason.

The study will have two parts – PART 1 and PART 2

PART 1

You will be asked to visit the clinic to do some tests. We will record your weight, waist measurement, blood pressure and heart rate and check your current medications. We also collect a blood and urine test to assess your health, check whether you have diabetes and check your cholesterol level. If you could become pregnant, we will also do a pregnancy test. You will need to fast (not eat) for 9-12 hours before this blood test. This visit is to confirm whether it is OK for you to join the study.

You will complete surveys about your quality of life and any gut symptoms. This will take around 15 minutes to complete.

If the tests confirm you are OK to join the study, we will give you metformin to take for 10 weeks and ask you to complete some questionnaires if you have any gut symptoms.

You will be asked to come to the clinic 2 more times – after 4 weeks and 8 weeks.

• At these visits we will take your blood pressure and do a blood test. These visits last about 20-30 minutes.

We will also contact you briefly by phone between your clinic visits. We will check how you are getting on with the metformin and if your other medications have changed. Depending on how you are getting on, we may ask you to change the number of tablets of metformin you take.

After 10 weeks you will stop taking metformin.

If you are unable to tolerate 2 tablets of metformin a day, you will not continue on the study.

If you have been able to tolerate 2 tablets of metformin a day, you will stop taking metformin for 2 weeks. After that time, we will arrange a clinic visit to see whether you can enter PART 2 of the study. During this visit we will:

• Check if your other medications have changed
• Collect a blood and urine sample to assess your health, check again whether you have diabetes and check your cholesterol level. If you could become pregnant, we will also do a pregnancy test. You will have to fast (not eat) for 9 to 12 hours before the blood test.

• Collect and store extra blood samples to test how well your kidneys are working and whether the metformin has worked. [This only applies if your hospital is doing this part of the trial].

• Ask you to complete surveys about your quality of life and any gut symptoms. This will take around 15 minutes to complete.

When your doctor has the results of these tests, they will contact you to let you know whether you are suitable for PART 2 of the study.

We will use a process called randomisation to allocate you to a study group. One group will take metformin for 24 months and the other group will take a placebo (an inactive pill) for 24 months. Click here to find out why this study uses randomisation to choose your group.

Neither you nor your doctor will know what medication you are taking.

After 1 month we will telephone you to ask about your medication. This will take 5-10 minutes.

You will visit the clinic after 3 months and then every 6 months. Visits will take about 1 hour.

We will:

• Record your weight, waist measurement, blood pressure and heart rate and check if your other medications have changed
• Collect a blood and urine sample to assess your health, check again whether you have diabetes and check your cholesterol level. If you could become pregnant, we will also do a pregnancy test. You will have to fast (not eat) for 9-12 hours before the blood test.
• Ask you to complete surveys about your pain (takes about 5 to 10 minutes to complete)
• Give you more trial medication (not applicable at 3-month visit)
• Ask you to return unused trial medication (not applicable at 3-month visit)

At the 12-month and 24-month visits we will also:

• Test your vitamin B12 level as part of your blood test
• Ask you to complete surveys about how you feel (quality of life) and your gut symptoms. This will take about an extra 10 minutes to complete
• Collect and store extra blood samples to test how well your kidneys are working. [This only applies if your hospital is doing this part of the trial]

While you are on the study you should:

• Continue with your normal daily activities throughout the trial.
• Take tablets with food during your evening meal (this can reduce stomach upsets).
• Let your doctor know straight away if you become unwell or have concerns.
• Know which medications to avoid taking while on the study. Your doctor will tell you which medications you should avoid. You can also click here for this list of medications.

You may not benefit from taking part in the study, but if you take part, you will be helping to improve understanding of how to treat patients with ADPKD.

All medications may have side effects. The most common side effects people have when they first start taking metformin are – nausea, vomiting, and diarrhea and skin reactions (redness, rash, itching or rash). The effects of metformin on unborn babies are unknown.

A rare, but serious side effect of metformin is lactic acidosis. You should talk to your doctor straight away if you have these symptoms:

– Nausea, vomiting, stomach pain	– Sleepiness
– Trouble breathing	– Dizziness or light-headedness
– Feeling weak, tired or generally unwell	– Shivering, feeling extremely cold
– Unusual muscle pain	– Slow heartbeat

To find out whether metformin was effective or not, study researchers will ask your permission to access your Medicare Benefits Scheme (MBS) and Pharmaceutical Benefits Scheme (PBS) data so we can collect information on how many health services you use during the study.

Your data will also be linked to other sources of information held by government agencies. This information includes records on hospital admission, hospital visits, the cost of each visit, survival, and use of medications.  Once your data are linked, all personal information (including name, date of birth and address) will be removed. 

The study sponsor (The University of Queensland) will collect, store, and send the above personal details to the Data Linkage office in a safe manner.

Click here to find out more about how your data is used and linked to other data for the research and more about how your privacy and confidentiality are protected.

During the study, routine blood and urine samples will be taken as part of your normal care. These samples will be tested in your hospital or local pathology lab, then destroyed.

[Delete if not applicable at the site name] Researchers are trying to learn more about ADPKD and how your body reacts to metformin. If you give your consent for the collection of extra blood when routine blood samples are taken, this blood will be frozen and stored for testing later.   

Click here to find out more about this optional study from your blood samples

The study is being led and organised by the University of Queensland. It is funded by a government grant.

More information on this trial can be found by clicking here.