Hypertension Related Damage to the Microcirculation in South Asian: Emergence, Predictive Power and Reversibility

Hypertension Related Damage to the Microcirculation in South Asian: Emergence,Predictive Power and Reversibility

Damage to very small blood vessels is a consequence, but can also precede high blood pressure. Such damage, measured by disturbances in the vessels in the retina (back of the eye) is a strong predictor of heart disease and stroke. South Asian people have one of the highest rates of hypertension in the world (30% in adults). In Pakistan, this is usually severe, undetected and untreated. The Wellcome Trust has already funded a study of blood pressure control in adults and children in this population. We propose a substudy, taking photographs of the retina and making measurements of the vessels, to determine whether such blood pressure related changes occur at an early age in young children with a family history of high blood pressure compared to those without, whether such changes predict an increase in blood pressure over time, and whether, in adults, such changes can be reversed by blood pressure treatment. The hypothesis of our study is: young offspring of South Asian people with hypertension have a disturbed microcirculation, as assessed by abnormalities of retinal vessels, compared to offspring of normotensive parents. Our 2nd hypothesis is: Abnormal retinal vascular geometry will improve proportionately to achieved reductions in BP.

Study Overview

• Status: Unknown
• Conditions: Hypertension; Cardiovascular Disease; Diabetes; Retinopathy
• Intervention / Treatment: Behavioral: GP training and Health Education

Detailed Description

Background

The role of the microcirculation is increasingly being recognized in the etiopathogenesis of cardiovascular disease. Delays in this recognition are in part due to the difficulty of studying the microcirculation non-invasively, in large numbers of individuals. Retinal vessels provide an easily accessible "window" to the microcirculation. Abnormalities of the retinal vasculature have been shown to be associated with cardiovascular risk factors and all cause mortality. Non-invasive assessment of the retinal circulation presents a valuable opportunity to study the structure and function of the microvasculature

Aims of the project

To compare geometry of retinal microvasculature of 1) hypertensive vs normotensive adults, 2) children aged 10 to 14 years of hypertensive parent (test group) versus normotensive parent (control group), and, 3) to assess the impact of blood pressure lowering on these changes over 2 years.

Primary outcome would be abnormal retinal geometry defined as the composite outcome of a) abnormal arteriolar length: diameter ratios (a measure of relative arteriolar narrowing), b) narrowed branching angles (an indicator of arteriolar rarefaction), or c) disturbed junction exponents (a marker of endothelial dysfunction.

Significance of the study

If successful, this work could be extended to address future questions, including the predictive value of these abnormalities for development of diabetes and hypertension as well as CVD; to explore further the role of microvascular disturbances in disease etiology, and to assess the impact of drug therapy on these abnormalities and their relationship to outcomes in the South Asian population

• Study Type: Interventional
• Enrollment: 2880
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Pakistan
  • Sindh
    • Karachi, Sindh, Pakistan, 74800
      • Aga Khan University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 9 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

All subjects aged 9 years or over residing in randomly selected communities

Exclusion Criteria:

Pregnancy

Those who have severe co-morbid conditions

Patients with known history of glaucoma will be excluded from our study because instillation of mydriatic drops was thought to be hazardous for them.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: Single

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Primary outcome would be abnormal retinal geometry defined as the composite outcome of a) abnormal arteriolar length: diameter, b) narrowed branching angles, or c) disturbed junction exponents.

Collaborators and Investigators

• Sponsor: Aga Khan University
• Collaborators: Imperial College London
• Investigators: Principal Investigator: Tazeen H Jafar, MD, MPH, Aga Khan University; Study Chair: Nish Chaturvedi, MD, MFPHM, Imperial College London; Study Chair: Alun Hughes, MD, Phd, Imperial College London; Study Chair: Juanita Hatcher, Phd, MSc, Aga Khan University; Study Chair: Simon Thom, MD, FRCP, Imperial College London; Study Chair: Khabir Ahmad, MD, MSc, Aga Khan University; Study Chair: Muhammad Saleem Khan, MSc Epi&Bio, Aga Khan University

Study record dates

Study Major Dates

• Study Start: May 1, 2006
• Study Completion: June 1, 2009

Study Registration Dates

• First Submitted: May 30, 2006
• First Submitted That Met QC Criteria: May 30, 2006
• First Posted (Estimate): May 31, 2006

Study Record Updates

• Last Update Posted (Estimate): May 31, 2006
• Last Update Submitted That Met QC Criteria: May 30, 2006
• Last Verified: May 1, 2006

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vascular Diseases; Hypertension; Cardiovascular Diseases
• Other Study ID Numbers: DHCPP00493