The Medicines Monitoring Unit at the University of Dundee is running a new type of study that aims to improve the effectiveness and safety of commonly prescribed medicines. This is called the EVIDENCE study (EVaulating Diuretics in Normal Care). In this particular study we are comparing two very similar medications used in the treatment of hypertension (high blood pressure), BENDROFLUMETHAZIDE and INDAPAMIDE.

The study works by assigning GP practices to follow a prescribing policy regarding which diuretic they use in the treatment of hypertension. Currently either can be prescribed. Doctors in participating practices use the assigned policy to guide their prescribing choices and, where clinically appropriate, patients have their regular medications altered in-line with the policy. Routinely collected NHS data will be used to compare the safety and effectiveness of the medications so that, in future, doctors and patients have all the information they need to make the best treatment choices.

If you would like to know more about the more about the EVIDENCE study, please email or call the EVIDENCE team on 01382 383865. If you would like to know more about other trials that we are running please visit us at:

Please see the video below for a short overview of the EVIDENCE study.

Frequently Asked Questions

What is high blood pressure (hypertension)?

Hypertension is the medical term used for high blood pressure. It indicates that your blood pressure is consistently too high, requiring your heart to work harder to circulate blood throughout your body. High blood pressure is a serious condition as it can lead to heart and circulatory problems such as a heart attack or stroke.

What causes high blood pressure?

The cause of high blood pressure is not always known, most individuals develop high blood pressure due to their lifestyle, diet, or another medical condition.

What is the aim of the EVIDENCE trial?

The Evidence Study aims to compare the safety and effectiveness of Bendroflumethiazide and Indapamide, which are very similar and widely prescribed medications that are used to treat high blood pressure. We aim to determine if one is more effective and safer than the other or if they are the same. The results will aid GPs in making the best medical decisions in the future. The doctors in your practice has agreed that everyone in your practice who has been prescribed one of these high blood pressure medications will be given the same medication. The effectiveness of the medicine you are prescribed, and your safety will always be our top priority.

Who is funding the trial?

The study is being funded by and conducted by researchers at the University of Dundee, working with GP practices in Scotland and is supported by the NHS. A Study Doctor and Pharmacist will oversee the study and will be accountable to the Chief Investigator.

How long is the trial expected to last, and how long will I have to take part?

The EVIDENCE Study is expected to run for a minimum of 3 years.

How long will it be before the results of the trial are known?

The study results will be known shortly after the study has been closed and the results communicated to your GP Practice.

Has my GP been informed?

Yes. The EVIDENCE Study has been fully supported by your GP, and your practice is happy for you to be prescribed one of the medications.

Do I have to take part in the study?

NO. you do not have to take part and can opt out at any time. If you decide you do not want to take part, you can inform the EVIDENCE team via telephone, email, or the contact form on our webpage. The EVIDENCE team will contact your surgery to ensure your prescription is amended accordingly. Please make sure that you provide us with:
  • Full Name
  • Date of Birth
  • GP Practice
  • Contact details

Is my information kept confidential?

Yes. Protecting your privacy is very important. We will always protect the use of personal data with the appropriate security measures. No identifiable information will be removed from your GP practice.

What about my data privacy?

The EVIDENCE Study complies and adheres with all the requirements of General Data Protection Regulation, the Data Protection Act 1998, and NHS Scotland Code of Practice on Protecting Patient Confidentiality. Please see our privacy notice:

Where will I have to collect my medication from?

There will be no change to how your medication is prescribed or collected.

Will the new medicine do the same as the previous one?

Yes. Your new medication has been prescribed by your GP because it will work the same as the previous one.

What are the possible side effects of my treatment?

We do not anticipate any problems with this change. If you are concerned about any symptoms which you believe may be related to the change, please contact the study team so we can discuss this with you. If you believe your problem is urgent, please contact your GP.

Will I need additional blood pressure measurements, tests, or procedures?

There will be no requirements for additional blood pressure measurements to be taken or health checks to be carried out.

I have received my letter is there anything I am required to do?

You are not required to take any action. The work will be completed by your GP practice. If you are already on the medication selected for your practice, then nothing will change. Should you need to be switched to the new medication this will take place when you make the request for your repeat prescription. This means that when you request your next repeat prescription in the usual manner, you will receive the medication that your practice has agreed to prescribe.

What should I do if my medication is going to change to Bendroflumethiazide/Indapamide?

If your medication is changing to Bendroflumethiazide/Indapamide please finish your current medication and order your repeat prescription as usual. Your next repeat prescription will include the new tablets. Start taking them only after you have finished your current diuretic medication.

I am currently on Bendroflumethiazide 5mg and I have received Indapamide 2.5mg. Is the reduced dosage, OK?

Yes. Your new Indapamide dose of 2.5mg is equivalent to the 5mg of Bendroflumethiazide that you were previously taking and has been checked by your GP/pharmacist. So, although the milligram (mg) dosage has halved, you are still receiving the same effective dose of medication. If you have any concerns please contact the EVIDENCE study team, who will be happy to answer any questions you may have.

Is it safe for me to switch from Indapamide slow-release formulation to standard release Indapamide or Bendroflumethiazide 2.5mg?

Yes. They are equally clinically effective. There is no evidence indicating any clinically significant difference between them.

Who can I contact if I have a question or problem?

If you have any questions or problems, please speak with our EVIDENCE Study Team. You can contact us via:

Please provide us with the following information:

  • Full Name
  • Date of Birth
  • GP Practice
  • Contact details

Who approves the study?

Clinical research cannot begin without the approval of the relevant regulatory authorities. Before and during the study, all study-related materials are reviewed. The regulatory authorities evaluate the protocol's scientific design, the safety of participants, any ethical implications and the feasibility. The protocol is a document that describes the plan for how the research study will be conducted. It ensures the safety of the study patients and integrity of the study data.

Our research studies, including EVIDENCE, are reviewed and approved by the relevant regulatory authorities. EVIDENCE has been approved an NHS Research Ethics Committee (REC) and all of the Scottish Health Boards.

Who are the Research Staff working on the study?

All our staff members involved in conducting research studies, such as doctors, nurses, trial managers, and pharmacists, are fully trained and employed by the University of Dundee. Everyone on the research team is trained in the principles of Good Clinical Practice, which covers the rules and regulations for conducting and managing research.

Need to get in touch?

By Post

MEMO Research, Level 7,
Ninewells Hospital and Medical School,
Dundee, UK,


By Phone

01382 383865
Monday to Friday
8.45am to 5.00pm



For more detailed information about the study, please click the link below to open the Patient Information Sheet for this study. Please also feel free to visit the NHS "Changing Your Medication" and NICE guidelines links below. On those pages, you will find official NHS policy on changing existing prescriptions for taking part in studies, and the guidelines that we adhere to for this type of reasearch.

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The team
Here to help you

Angela Flynn

Study pharmacist responsible for implementing the study in GP practices. She also provides training for other pharmacists throughout Scotland.

Dr Alex Doney

Senior Clinical Lecturer at the University of Dundee and Honorary Consultant Physician at Ninewells Hospital with a specialist interest in Blood Pressure and Cardiovascular risk.

Amy Rogers

Clinical Research Fellow focusing on large scale drug safety and effectiveness trials. Particular interests include pragmatic research methodologies and evidence based prescribing in primary care.

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Any questions?