Plain English Summary
Background and study aims
Obesity is a term used to describe somebody who is very overweight, with a lot of body fat. It's a common problem, estimated to affect around one in every four adults and around one in every five children aged 10 to 11 in the UK. People who are obese are at risk of a number of serious and potentially life-threatening conditions, such as high blood pressure. High blood pressure is dangerous because it can have no symptoms, and increases the risk of a heart attack or stroke. It can also cause permanent damage to vital organs, such as the kidney, eye, brain and heart. Normally, high blood pressure can be treated with medications but these medications don’t work very well in obese patients and we’re not sure why. Most information on blood vessel structure comes from blood vessels studied in a laboratory. Here, we are using a technique which allows us to view blood vessels in the patient directly. Eye (retinal) blood vessel analysis is a non-invasive way to measure the structure of small blood vessels in a patient. The aim of this study is to get a better understanding of the differences in small blood vessel structure between obese patients and lean patients.
Who can participate?
Adults with a BMI over 30 or lower than 25.
What does the study involve?
Participants have non-invasive tests to check how well their blood vessels are functioning. Two of these tests are eye tests. There is also a blood test.
What are the possible benefits and risks of participating?
There are no risks or benefits to participating in this study.
Where is the study run from?
Wellcome Trust Clinical Trials Facility, Central Manchester University Hospitals Trust (UK)
When is the study starting and how long is it expected to run for?
June 2015 to January 2017
Who is funding the study?
British Heart Foundation (UK)
Who is the main contact?
Dr A Greenstein (scientific)
Trial website
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
V1; 13/4/14
Study information
Scientific title
Identification of cardiovascular changes in obesity using dynamic and static retinal vessel analysis
Acronym
Study hypothesis
Changes in retinal vessel function can be correlated with obesity, blood pressure, pulse wave velocity and blood metabolic markers.
Ethics approval
North West - Greater Manchester South Research Ethics Committee, 29/07/2015 ref: 15/NW/0548
Study design
Single site cohort observation
Primary study design
Observational
Secondary study design
Cohort study
Trial setting
Hospitals
Trial type
Screening
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet.
Condition
Cardiovascular disease associated with obesity
Intervention
All participants who express an interest in study participation will be invited to attend Manchester Clinical Research Facility. Following informed consent procedure (estimated to take approximately 15mins), all participants will undergo:
1. Assessment of past medical history and physical examination: height, weight, waist circumference (10 mins)
2. Pupil dilation (Tropicamide eye drops applied taking 2 minutes to perform but up to 20 minutes to take effect)
3. Blood sampling – up to 10ml (2 teaspoon blood) takes up to 10mins to perform
4. Pulse Wave velocity measurement lay in supine position (10 mins)
5. Blood pressure will be recorded at the start and end of procedure but also throughout the assessment using a wrist cuff
6. Dynamic retinal vessel analysis (flicker stimulation) (15 mins)
7. Static retinal vessel analysis (10 mins)
8. Oxygen saturation will be measured by taking a photograph of the fundus of the eye (5 mins)
9. Carbon dioxide inhalation – during the imaging examination of the eye, a mixture of 95% air/5% carbon dioxide will be administered via nasal cannula (procedure takes 2-3 minutes but gas will be administered for only 45 seconds)
10. On completion of the assessment, participants will be given the general advice leaflet for Tropicamide and advised not to drive for 4 hours This completes study participation.
Total duration of assessment not expected to be more than 2 hours.
Intervention type
Other
Phase
Drug names
Primary outcome measure
Vascular function measured by degree of response to flicker stimulation, retinal arteriolar-venular ratio (AVR) and blood oxygen saturation on the assessment day.
Secondary outcome measures
Peripheral measurements: blood pressure, pulse wave velocity and blood levels of HbA1c and blood lipids (triglycerides, LDL and HDL cholesterol) on the assessment day.
Overall trial start date
01/02/2015
Overall trial end date
31/12/2020
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
Patient-participants:
1. Willing and capable to provide consent to participation
2. BMI greater than 30
3. No known ocular diseases
4. No known concurrent clinical problem likely to interfere with participation or completion of the study
Healthy controls:
1. BMI lower that 25
2. No known diabetes
3. No known ocular diseases
4. No known concurrent clinical problem likely to interfere with participation or completion of the study
Participant type
Mixed
Age group
Adult
Gender
Both
Target number of participants
30 healthy lean controls and 30 obese patient-participants
Participant exclusion criteria
1. Under 18 years old
2. Intubated/ventilated patients
3. Unwilling to give consent to participation OR advised by consultee that this would be against the patient’s wishes
4. Smoker
5. If eaten with in an hour of the examination
6. If drank alcohol within an hour of the examination
7. If drank coffee within an hour of the examination
8. If overly hungry
9. Recently treated infection
10. Known ocular diseases
11. Known concurrent clinical problem likely to interfere with participation or completion of the study
Additional exclusion for healthy controls:
1. Diabetes
2. BMI above 25
Recruitment start date
01/06/2015
Recruitment end date
30/06/2020
Locations
Countries of recruitment
United Kingdom
Trial participating centre
Manchester Clinical Research Facility
Oxford Road
Manchester
M13 9WL
United Kingdom
Funders
Funder type
Government
Funder name
National Institute for Health Research
Alternative name(s)
NIHR
Funding Body Type
government organisation
Funding Body Subtype
Federal/National Government
Location
United Kingdom
Results and Publications
Publication and dissemination plan
Planned publication in a peer reviewed journal.
IPD sharing statement:
The datasets generated during and/or analysed during the current study are/will be available upon request from adam.greenstein@manchester.ac.uk
Intention to publish date
31/12/2021
Participant level data
Available on request
Basic results (scientific)
Publication list