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

NCT ID: NCT00331370

Last Updated: 2006-05-31

Basic Information

• Recruitment Status: UNKNOWN
• Clinical Phase: NA
• Total Enrollment: 2880 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2006-05-31
• Study Completion Date: 2009-06-30

Brief Summary

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.

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

Conditions

Hypertension; Diabetes; Cardiovascular Disease; Retinopathy

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: FACTORIAL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: SINGLE

Interventions

GP training and Health Education

Intervention Type: BEHAVIORAL

Eligibility Criteria

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.

• Minimum Eligible Age: 9 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Imperial College London

OTHER

Sponsor Role: collaborator

Aga Khan University

OTHER

Sponsor Role: lead

Principal Investigators

Tazeen H Jafar, MD, MPH

Role: PRINCIPAL_INVESTIGATOR

Aga Khan University

Nish Chaturvedi, MD, MFPHM

Role: STUDY_CHAIR

Imperial College London

Alun Hughes, MD, Phd

Role: STUDY_CHAIR

Imperial College London

Juanita Hatcher, Phd, MSc

Role: STUDY_CHAIR

Aga Khan University

Simon Thom, MD, FRCP

Role: STUDY_CHAIR

Imperial College London

Khabir Ahmad, MD, MSc

Role: STUDY_CHAIR

Aga Khan University

Muhammad Saleem Khan, MSc Epi&Bio

Role: STUDY_CHAIR

Aga Khan University

Locations

Aga Khan University

Karachi, Sindh, Pakistan

Countries

Pakistan

Central Contacts

Tazeen H Jafar, Md,MPH

Role: CONTACT

Phone: 0092-4930051

Email: tazeen.jafar@aku.edu

Muhamamd Saleem Khan, MSc Epi&Bio

Role: CONTACT

Phone: 0092-4930051

Email: muhammad.saleem@aku.edu

Facility Contacts

Tazeen H Jafar, MD, MPH

Role: primary

Muhammad Saleem Khan, MSc Epi&Bio

Role: backup

Other Identifiers

DHCPP00493

Identifier Type: -

Identifier Source: org_study_id