Diurnal BP Patterns in Those at Increased Risk of CVD

Study Overview
=================
Brief Summary
-----------------
In health, blood pressure (BP) falls at night by >10% compared with day-time values. This natural dipping pattern is important as without it there is an increased risk of cardiovascular disease (CVD). Recent evidence suggests that chronotherapy (taking anti-hypertensive medication at bedtime instead of in the morning) may enhance nocturnal BP dipping and reduce the risk of CVD events. There is therefore an urgent need to characterise diurnal BP patterns in patients who may be at risk of reduced nocturnal dipping in order to maximise protective therapy in all those who would benefit. Similarly, it has previously been demonstrated that increased arterial stiffness is associated with increased CVD risk, however little is known about whether loss of diurnal variations in arterial stiffness confer addition risk. Kidney disease is independently associated with increased CVD events, but the exact makeup of this risk is not clear. Within this heterogenous cohort several very distinct groups exist including those with acute kidney injury (AKI), chronic kidney disease (CKD), inflammatory conditions like small vessel vasculitis (SVV), and those who have either donated or received a kidney transplant. Diurnal BP and arterial stiffness patterns within these patient groups are not well characterised. The investigators will recruit patients at increased risk of CVD from the Royal Infirmary of Edinburgh Renal and Vasculitis Clinics. Participants will undergo 24-hour ambulatory BP and arterial stiffness measurement in conjunction with day- and night-time blood and urine sampling on two separate occasions. This study aims to characterise diurnal patterns of BP and arterial stiffness in patients at increased risk of CVD and compare findings with healthy controls. In doing so, the investigators aim to allow more targeted CVD risk reduction strategies and improve long-term patient outcomes.

Official Title
-----------------
Diurnal Blood Pressure and Arterial Stiffness Patterns in Those at Increased Risk of Cardiovascular Disease

Conditions
-----------------
Cardiovascular Risk Factor, Blood Pressure, Arterial Stiffness, Chronic Kidney Diseases

Intervention / Treatment
-----------------
* Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients will be eligible to take part in the study if they attend NHS Lothian inpatient or outpatient services and can be classified as being at increased risk of CVD. This will include, but is not limited to, the following subgroups: CKD as defined by the Kidney Disease Outcome Quality Initiative (K/DOQI) classification AKI as defined by the Kidney Disease Improving Global Outcomes (KDIGO) classification Small vessel vasculitis Kidney transplant recipient Kidney donor We will also recruit a healthy control group from the community. Exclusion Criteria: Age <18 years and >90 years Lack of ability to provide informed consent

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Health<br>Healthy individuals with no known medical condition and taking no regular medication | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|
| Acute kidney injury<br>Individuals with acute kidney injury as defined by KDIGO criteria | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|
| Chronic kidney disease<br>Individuals with chronic kidney disease as defined by KDIGO criteria | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|
| Small vessel vasculitis<br>Individuals with active small vessel vasculitis an diagnosed by a specialist physician | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|
| Kidney transplant recipient<br>Individuals who have received a kidney transplant | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|
| Kidney donor<br>Individuals who have donated a kidney for transplantation | Diagnostic Test: Assessment of 24 hour blood pressure and arterial stiffness<br>* Assessment of 24 hour blood pressure and arterial stiffness using Mobil-o-graph device<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Nocturnal BP dip | Percentage change between mean day-time and mean night-time blood pressure | 24 hours | 
| Nocturnal arterial stiffness dip | Percentage change between mean day-time and mean night-time arterial stiffness | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in urine ET-1 concentration when measured in the morning (06:00 - 12:00) and in the evening (18:00-00:00) | Measurement of urine ET-1 concentration in the morning (06:00 - 12:00) and in the evening (18:00-00:00) | Morning (06:00-12:00) and evening (18:00-00:00) | 
| Change in plasma ET-1 concentration when measured in the morning (06:00 - 12:00) and in the evening (18:00-00:00) | Measurement of plasma ET-1 concentration in the morning (06:00 - 12:00) and in the evening (18:00-00:00) | Morning (06:00-12:00) and evening (18:00-00:00) |