PD MED is a large national research study of treatments for Parkinson’s disease (PD for short). Please find a list of frequently asked questions below.

What is Parkinson's disease?

Parkinson’s disease is a movement disorder that affects various parts of the body, causing stiffness in the muscles, slowness, difficulty when starting movements, and tremor in some people. This is caused by a reduction in the numbers of brain cells that produce a chemical called dopamine. These symptoms appear over many years but drug treatments can help slow the effects of this process.

What drug treatments are currently available?

Several different types of drugs are available to treat the symptoms of PD. These drugs fall into a number of different categories (such as levodopa, dopamine agonists, MAOB inhibitors and COMTI inhibitors), and within each class there may be more than one drug available. We know from previous studies that each of these types of drug can be effective at controlling symptoms of PD and all of these treatments have been widely used, with some doctors preferring one type and other doctors another.

If these treatments are available why do we need a clinical trial?

Although we know that these drugs do work, little is known about how these drugs compare with each other and whether or not some are better than others. Furthermore, the impact of the drugs on the daily life of people with PD (and on their carers) has not been investigated thoroughly. PD is, unfortunately, a common condition and we need to be absolutely sure that any new – and possibly expensive – drugs really are better than the older drugs before they become standard treatment. This means weighing up all the advantages and disadvantages of each type of drug and seeing which is best overall. This is what we hope to find out from the PD MED study.

Who is taking part in the study?

Two types of patient were able to enter the PD MED study:

  • Patients with early PD (who had recently been diagnosed with PD and had not been taking drug treatment for more than 6 months).
  • Patients with later PD (whose PD had progressed such that the drugs they had been taking were no longer able to control the symptoms effectively).

Which patients got which class of drug?

Since we do not know which class of drugs is best, we need to compare them to find out. In order to do this, patients were allocated to one of three groups at random by the central study office. If their doctor believed that all three drugs would be suitable for them, they had an equal chance of drawing any one of the three. The drugs being tested are:

For patients with early PD:

  • levodopa alone
  • dopamine agonist (this increases the amount of dopamine available in the brain)
  • MAOB inhibitor (this stands for monoamine oxidase type B inhibitor and works by reducing the breakdown of dopamine in the brain)

For patients with later PD:

  • dopamine agonist
  • MAOB inhibitor
  • COMT inhibitor (this stands for catechol-O-methyltransferase inhibitor and works by reducing the breakdown of levodopa in the brain

If the patient’s doctor felt that it would be inappropriate for them to receive one of the drugs (for example, levodopa or MAOB inhibitor), this patient would just be allocated between the other two, and they had a 50:50 chance of receiving either of them. (If the doctor believed that only one of the drugs is suitable for a particular patient, then they were not eligible for the study.)

If more than one drug is available in the class to which the patient is allocated, the doctor was able to choose which one to give. For patients who were allocated to either dopamine agonist or MAOB inhibitor, their doctor may also give levodopa later on if this is felt to be necessary, though this will probably be at a lower dose than for patients who are receiving levodopa alone. Whatever drug, or drugs, patients receive during the study, they will still have access to the same medical and nursing support that would be provided if they were not in the study.

What does taking part in the PD MED study involve?

Taking part in the study does not require any extra physical tests at all and no extra clinic visits are necessary for patients who are participating. Each patient will be asked to complete a straightforward set of questions when they enter the study, 6 months later, 12 months later and then annually. The patient’s carer, if they have one, will also be asked to answer some questions to find out how helping to look after someone with PD affects their life. The follow-up questionnaires will be sent to the patient, and their carer, by post and a pre-paid envelope will be provided for their return. It should not take more than half an hour to complete them each time.

The study involves taking the drug, or drugs, allocated regularly as prescribed by the patient’s doctor. The actual regimen will depend on which drugs patients receive and how severe their symptoms are. The patient’s doctor will explain how and when the drugs should be taken. It is important that patients tell their doctor of any changes in their symptoms so that the dosage of the drugs can be adjusted if necessary.

What are the risks of taking these drugs?

Doctors generally agree that all the drugs prescribed in the PD MED study are safe but, as with any treatment, we can not guarantee that there will be no side effects. Doctors will tell patients about the possible side effects of the treatments that they receive. It is important that patients tell their doctors if the study drugs cause upsets so that they can decide whether other treatment is required or if the drug needs to be stopped. If new information comes to light during the course of the study, doctors will tell patients taking part and discuss with them whether they should continue in PD MED.

Are there any benefits for patients from taking part in the study?

All of the treatments being used in this study are known to help control the symptoms of PD and are already widely used, so the treatment patients receive will be at least as good as that available outside the study. We hope that the information obtained from this study will help us to treat patients with PD more effectively in the future.

Can patients withdraw from the study?

Yes, patients can decide to withdraw from the study at any time. Signing the consent form does not commit them to receiving the treatment allocated and withdrawal will not affect the standard of care that they receive subsequently. If patients do change their mind later they do not have to give a reason, but it would help the research if they could still complete the questionnaires to let the study organisers know how they are doing.

Does participation in the study affect patients' legal rights?

There are no special arrangements for compensation in the (unlikely) event that patients are harmed as a result of taking part in the study. But, whether or not patients take part, they will retain the same legal rights as any other patient treated in the NHS.

All information collected in the study will remain strictly confidential in the same way as other medical records. The patient’s GP will need to be told that they are taking part in the study as he/she usually supplies their prescriptions. The information will be put into a computer and analysed, but individual patients will not be identified when the results are reported.

What will happen to the results of the study?

At the end of the minimum follow-up period for the trial, the answers that patients provide in the questionnaires will be analysed and a report written for a leading medical journal. The NHS will help ensure that doctors treating PD are aware of the results, so that patients can be treated with the best treatments.

Who is organising and funding the study?

The central study organiser is the University of Birmingham Clinical Trials Unit, which has experience of running very large trials like PD MED. The study is funded by the NHS Research & Development Programme. The doctors involved are not being paid for recruiting patients into the study. The study has also been reviewed by the West Midlands Multi-centre Research Ethics Committee and the Local Research Ethics Committee at your hospital. There is no drug company involvement.

Do you have any other questions?

If you still have questions about the study now or later you should ask your hospital doctor or nurse. The University of Birmingham Clinical Trials Unit, who are organising the study, may also be able to help. Our contact details can be found here.

How do I go about taking part in the study?

Unfortunately PD MED is now closed to recruitment, so no further patients can take part.

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