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Targeting and incentives for prevention
Initial registration date
October 28, 2019
June 23, 2020 5:03 AM EDT
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Other Primary Investigator(s)
Erasmus School of Economics
Additional Trial Information
Incentivizing the take-up of preventive health services can be effective to increase access in low-income countries. Yet even when care is incentivized, some individuals may not be sensitive to price because they still fail to see the benefits of using preventive services on their health. This may be particularly the case when individuals suffer from diseases whose symptoms are not salient, or when the hassle costs of setting up an appointment may outweigh its perceived benefits. Hence, policy-makers may be concerned that universal financial incentives for preventive services that fail to target the most at-risk individuals can generate wastage. In this study, we compare three ways of providing a preventive medical check-up for cardiovascular diseases (CVD): (i) free provision of the medical check-up (which includes a blood test and a consultation with a doctor); (ii) receiving a small payment for completing the check-up; (iii) receiving a very small, medium or large financial reward depending on whether the patient is diagnosed, at the check-up, to have respectively a small, medium or large risk of suffering from CVDs in the next 10 years. Comparing take-up of preventive care and behavior change at follow-up across these three groups allows us to test whether varying the level of the incentive by risk status is a cost-effective way to better screen and reach individuals the most at risk.
Across all arms, eligible individuals will be given basic information about CVDs, personalized information about their risk factors, and a voucher for a free preventive check-up for CVDs, including a blood test and a medical consultation.
The voucher will come with varying benefits depending on the treatment arm to which individuals are randomly assigned: 1. Individual 'universal' incentive: all individuals who do the preventive check-up receive a small monetary payment. 2. Risk-based incentive: individuals who do the check-up receive a monetary payment which is determined by the outcome of the check-up: if they are found to suffer from a low, medium or high risk of developing a CVD, they respectively receive a low, medium or high payment. While neither the individuals nor the healthcare providers know this risk ex-ante, individuals know whether they have some or many of the risk factors associated with increased risk level. 3. Control. Individuals who do the check-up receive do not receive any additional benefit.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Primary outcome of impact of voucher= take-up of preventive check-up; (full or partial)
Primary outcomes for impact of preventive check-up = knowledge and risk perceptions; self-reported health-related behaviors (self-reported diet and physical activity, health-care seeking, adherence to treatment); health investments; health outcome (blood pressure)
Primary Outcomes (explanation)
Secondary Outcomes (end points)
Partial uptake (blood test only) and timing of preventive check-up
Secondary Outcomes (explanation)
The experiment will be conducted between November and December 2019 in San Salvador, the capital city of El Salvador. Study participants are recruited amongst the clients of a microfinance institution that seeks to improve awareness and prevention of cardiovascular diseases amongst its clientele and offers free access to a medical clinic.
To be eligible, an individual has to be at least 40 years old. After they consent to take part in the study, eligible individuals complete a baseline survey, receive information about cardiovascular diseases and obtain a voucher for a free preventive check-up. Individuals are randomized by the enumerator to one of the study arms following a randomization sequence generated prior to the start of the fieldwork, using a web-based randomization tool. To ensure a high degree of balance and obtain the desired proportions across treatment groups within each stratum, we stratify the randomisation by a measure of CVD risk (low risk vs. medium or high risk) calculated based on the self-reported information and health outcomes (BMI, blood pressure) collected in the baseline survey (while this measure is expected to be correlated with the measure computed during the check-up it is not necessarily identical).
Experimental Design Details
Individuals are allocated to groups following a pre-specified randomization sequence generated prior to the start of the fieldwork using a web-based randomization tool (https://www.sealedenvelope.com/simple-randomiser/v1/lists). As each fieldworker follows a different sequence, the randomization of individuals into one of the three study arms is partly driven by the timing of their recruitment during the day, but also by their (random) allocation to one of the five fieldworkers completing the recruitment.
Was the treatment clustered?
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
Comite Nacional de Etica de la Investigacion en Salud
IRB Approval Date
IRB Approval Number
London School of Economics
IRB Approval Date