The Effect of Household-based Screening on Blood Pressure Changes in South Africa

NCT ID: NCT03762304

Last Updated: 2018-12-07

Basic Information

• Recruitment Status: COMPLETED
• Total Enrollment: 3986 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2008-02-29
• Study Completion Date: 2017-12-31

Brief Summary

This study will evaluate the effect of household-based screening and care encouragement for blood pressure on subsequent changes in blood pressure. The study uses a quasi-experimental regression discontinuity design with existing population-based secondary data from the 2008, 2010, 2012, 2014, and 2017 waves of the National Income Dynamics Study in South Africa.

Detailed Description

Household-based screening and referral to care for blood pressure may improve blood pressure control at the population level in many low- and middle-income countries.

This observational study will use a quasi-experimental regression discontinuity design to evaluate the effect of household-based screening for blood pressure with care encouragement for potentially hypertensive individuals on subsequent changes in blood pressure over time.

Individuals had their blood pressure measured in the household as part of the National Income Dynamics Study data collection. If individuals had a measured blood pressure in the hypertensive zone, they were told that they had elevated blood pressure, that high blood pressure can lead to life threatening consequences, and that they should seek further care. The study exploits the fact that individuals were given this information based on a hard blood pressure cutoff. Therefore, the investigators will evaluate the causal effect of this household-based intervention in the absence of randomization by comparing individuals with a baseline blood pressure just above and below the cut off.

Conditions

Hypertension; Blood Pressure

Keywords

Causal inference; Regression discontinuity

Study Design

• Observational Model Type: OTHER
• Study Time Perspective: PROSPECTIVE

Study Groups

Intervention group

The intervention group consists of individuals with a measured blood pressure just above the hypertensive cut-off of 140 mmHg systolic or 90 mmHg diastolic blood pressure who have never previously been diagnosed as hypertensive and are not taking medication to lower their blood pressure. The exact upper bound on blood pressure will be determined empirically. Individuals in the intervention group were told that that their blood pressure was high, that high blood pressure can lead to life threatening consequences, that blood pressure control can reduce these negative consequences, and that they should seek follow-up care for their blood pressure.

Household blood pressure screening with care encouragement

Intervention Type: OTHER

During the household survey visit, survey enumerators collected two measurements of the respondent's blood pressure. If either of the measurements exceeded 140 mmHg systolic or 90 mmHg diastolic, enumerators told participants: "Your blood pressure readings are higher than normal. High blood pressure is dangerous because it makes the heart work too hard. High blood pressure increases the risk of heart disease and stroke. High blood pressure can also cause other problems, such as heart failure, kidney disease, and blindness. You can control high blood pressure by taking action." Then the enumerators recommend that an individual seek medical care within 2 months.

Control group

The control group consists of individuals with a measured blood pressure just below the hypertensive cut-off of 140 mmHg systolic and 90 mmHg diastolic blood pressure who have never previously been diagnosed as hypertensive and are not taking medication to lower their blood pressure. The exact lower bound on blood pressure will be determined empirically. These individuals were not given the care encouragement intervention.

No interventions assigned to this group

Interventions

Household blood pressure screening with care encouragement

During the household survey visit, survey enumerators collected two measurements of the respondent's blood pressure. If either of the measurements exceeded 140 mmHg systolic or 90 mmHg diastolic, enumerators told participants: "Your blood pressure readings are higher than normal. High blood pressure is dangerous because it makes the heart work too hard. High blood pressure increases the risk of heart disease and stroke. High blood pressure can also cause other problems, such as heart failure, kidney disease, and blindness. You can control high blood pressure by taking action." Then the enumerators recommend that an individual seek medical care within 2 months.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Age greater than or equal to 30
• Valid blood pressure measurements

Exclusion Criteria

• Prior diagnosis of hypertension
• Currently taking medication for blood pressure
• Measured with a blood pressure above 140 mmHg systolic or 90 mmHg diastolic in a previous wave of data

• Minimum Eligible Age: 30 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Emory University

OTHER

Sponsor Role: collaborator

Till Bärnighausen

OTHER

Sponsor Role: lead

Responsible Party

Till Bärnighausen

Alexander von Humboldt University Professor

Responsibility Role: SPONSOR_INVESTIGATOR

Principal Investigators

Nikkil Sudharsanan, PhD

Role: PRINCIPAL_INVESTIGATOR

Research group leader

Other Identifiers

RDD - BP - South Africa

Identifier Type: -

Identifier Source: org_study_id