Clinical trial NCT03762304: The Effect of Household-based Screening on Blood Pressure Changes in South Africa
Official title: The Effect of Household-based Screening on Blood Pressure Changes in South Africa: a Regression Discontinuity Study
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Hypertension
Blood Pressure
Keywords: Causal inference
Regression discontinuity
Lead sponsor: University Hospital Heidelberg
Sponsor class: OTHER
Collaborators: name: Emory University
First posted: 2018-12-03
Enrollment: 3986
Sex: ALL
Minimum age (years): 30
Standard ages: ADULT
OLDER_ADULT
Observational model: OTHER
Time perspective: PROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Individuals will be drawn from the 2008, 2010, 2012, and 2014 waves of the National Income Dynamics Study (NIDS) with the 2017 wave used only for follow-up. The NIDS is a nationally representative, household-based, survey of families and individuals from across South Africa.

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.

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

Primary outcomes:
measure: Two-year change in systolic blood pressure
timeFrame: Approximately two years based on the difference between survey waves in the years 2008, 2010, 2012, 2014, and 2017
measure: Nine-year change in systolic blood pressure
timeFrame: Baseline in 2008 and approximately nine years later in 2017.
Secondary outcomes:
measure: Health-seeking behavior
timeFrame: Cross-sectionally in 2010, 2012, 2014, and 2018
measure: Blood pressure treatment
timeFrame: Cross-sectionally in 2010, 2012, 2014, and 2018
Other outcomes:
Locations:
Study officials:
affiliation: Research group leader
name: Nikkil Sudharsanan, PhD
role: PRINCIPAL_INVESTIGATOR
References: