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Price Subsidies, Diagnostic Tests, and Targeting of Malaria Treatment: Evidence from a Randomized Controlled Trial
Last registered on April 12, 2016

Pre-Trial

Trial Information
General Information
Title
Price Subsidies, Diagnostic Tests, and Targeting of Malaria Treatment: Evidence from a Randomized Controlled Trial
RCT ID
AEARCTR-0001161
Initial registration date
April 12, 2016
Last updated
April 12, 2016 6:40 AM EDT
Location(s)
Region
Primary Investigator
Affiliation
Stanford University
Other Primary Investigator(s)
PI Affiliation
School of Public Health, Harvard University
PI Affiliation
Department of Economics, Dartmouth College
Additional Trial Information
Status
Completed
Start date
2009-05-01
End date
2010-12-31
Secondary IDs
Abstract
Both under- and over-treatment of communicable diseases are public bads. But efforts to decrease one run the risk of increasing the other. Using rich experimental data on household treatment-seeking behavior in Kenya, we study the implications of this trade-off for subsidizing life-saving antimalarials sold over-the-counter at retail drug outlets. We show that a very high subsidy (such as the one under consideration by the international community) dramatically increases access, but nearly one-half of subsidized pills go to patients without malaria. We study two ways to better target subsidized drugs: reducing the subsidy level, and introducing rapid malaria tests over-the-counter.
External Link(s)
Registration Citation
Citation
Cohen, Jessica, Pascaline Dupas and Simone Schaner. 2016. "Price Subsidies, Diagnostic Tests, and Targeting of Malaria Treatment: Evidence from a Randomized Controlled Trial." AEA RCT Registry. April 12. https://doi.org/10.1257/rct.1161-1.0.
Former Citation
Cohen, Jessica, Pascaline Dupas and Simone Schaner. 2016. "Price Subsidies, Diagnostic Tests, and Targeting of Malaria Treatment: Evidence from a Randomized Controlled Trial." AEA RCT Registry. April 12. https://www.socialscienceregistry.org/trials/1161/history/7646.
Sponsors & Partners

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Experimental Details
Interventions
Intervention(s)
Artemisinin combination therapies (ACTs) are now the only effective drugs in many malaria-endemic regions. In Kenya they are available in government clinics and retail drug stores. Public health clinics are often out of stock while the drug is unaffordable for the poor at full retail price. Subsidizing the drugs at the retail level can make the drug affordable but at the risk of over-treatment. The study attempts two interventions to test the trade-off between overtreatment and underteatment with ACTs.

Sample households are assigned to one of three treatment arms. In the first treatment arm, households received vouchers to purchase ACTs at full price from their nearest drug store. In the second treatment arm, the ACTs are subsidized at 92%, 88% or 80%. In the third treatment arm, households received subsidized rapid diagnostic malaria tests (RDT) in addition to the ACT subsidies.

In order to find out what fraction of people buying ACTs were truly malaria positive—a proxy for how well an ACT subsidy would be targeted—the researchers also selected a random subset of the households in all treatment groups to receive the offer of a “surprise” free RDT after they completed their transaction at the drug shop.
Intervention Start Date
2009-05-01
Intervention End Date
2009-12-31
Primary Outcomes
Primary Outcomes (end points)
The ultimate aim in this trial is to study how retail sector ACT subsidies impact both under-treatment (UT , the share of true malaria illnesses that are not treated with ACTs) and over-treatment ( OT , the share of non-malaria illnesses that are treated with ACTs). Since collecting the data to directly measure these outcomes was not logistically feasible, UT and OT are estimated indirectly by measuring:

1) Access: the share of all illness episodes treated with an ACT
2) Targeting: the share of ACT takers who are actually malaria positive
Primary Outcomes (explanation)
1) Access: A malaria positivity index was created for all illness episodes, based on a symptoms database (N = 533) collected from the study population. During unannounced home visits, trained surveyors asked if anyone was feeling ill, and if yes, they collected information about symptoms (using the same survey instrument used in the endline survey and then tested the patient for malaria with an RDT. This data is then used to impute a malaria probability to the universe of illness episodes enumerated at endline and all illnesses observed at drug shops.

2) Targeting: A subsample of those redeeming the ACT voucher are administered a “surprise RCT” unless they are part of the ACT+RDT treatment arm and had already redeemed their RDT voucher prior to getting their ACT.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Four rural drug stores, in a rural market setting, were selected. All households within a 4 km radius catchment area were sampled at baseline. At the end of the survey, the household was informed of its treatment status (full price ACT, ACT subsidy or ACT+RDT subsidy) and a voucher given accordingly. Each household was given two vouchers for ACT and two for RDT (if applicable) that could be redeemed at the study drug store. The drug dispensed was specific to the age of the patient. All ACTs and RDTs were provided by trained study officers posted at the drug shop for the duration of the study.

Additionally, to test what proportion of patients buying ACT was actually positive for malaria, a random subsample was given the option of a free RDT test after they had redeemed their ACT voucher. If the patient had not come to the drug store, the officer went to the patient’s home to administer the test. During the endline survey, administered about four months after the vouchers were distributed, households were informed the study was ending and all vouchers were collected back.
Experimental Design Details
Randomization Method
Computerized random number assignment algorithm and was stratified by drug shop, by the household’s distance to the drug shop (in quartiles), and by the presence of children in the household.
Randomization Unit
Household
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
Study not clustered
Sample size: planned number of observations
2789 households
Sample size (or number of clusters) by treatment arms
Control: no subsidy = 180 households
Treatment: ACT+ RDT subsidy = 1,625 households (92% subsidy = 394, 88% subsidy =619, 80% subsidy = 612)
Treatment: ACT subsidy only = 984 households (92% subsidy = 328, 88% subsidy =326, 80% subsidy = 330)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Pharmacy and Poisons Board of the Kenya Ministry of Medical Services
IRB Approval Date
2009-04-17
IRB Approval Number
PPB/ECCT-09/02/01
IRB Name
KEMRI/Kenya National Ethics Committee
IRB Approval Date
2009-02-03
IRB Approval Number
EMRI/RES/7/6/3/1
IRB Name
Innovations for Poverty Action Kenya
IRB Approval Date
2008-09-13
IRB Approval Number
N/A
IRB Name
University of California, Los Angeles
IRB Approval Date
2008-11-19
IRB Approval Number
G08-09-084
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
December 31, 2009, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
December 31, 2010, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
Study not clustered
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
2,645 households
Final Sample Size (or Number of Clusters) by Treatment Arms
Control: no subsidy = 173 households Treatment: ACT+ RDT subsidy = 1,539 households (92% subsidy = 366, 88% subsidy =586, 80% subsidy = 587) Treatment: ACT subsidy only = 933 households (92% subsidy = 306, 88% subsidy =310, 80% subsidy = 317)
Data Publication
Data Publication
Is public data available?
Yes
Program Files
Program Files
Yes
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
PRICE SUBSIDIES, DIAGNOSTIC TESTS, AND TARGETING OF MALARIA TREATMENT: EVIDENCE FROM A RANDOMIZED CONTROLLED TRIAL

Both under- and over-treatment of communicable diseases are public bads. But efforts to decrease one run the risk of increasing the other. Using rich experimental data on household treatment-seeking behavior in Kenya, we study the implications of this trade-off for subsidizing life-saving antimalarials sold over-the-counter at retail drug outlets. We show that a very high subsidy (such as the one under consideration by the international community) dramatically increases access, but nearly one-half of subsidized pills go to patients without malaria. We study two ways to better target subsidized drugs: reducing the subsidy level, and introducing rapid malaria tests over-the-counter.
Citation
Cohen, Jessica, Pascaline Dupas, and Simone Schaner. 2015. "Price Subsidies, Diagnostic Tests, and Targeting of Malaria Treatment: Evidence from a Randomized Controlled Trial." American Economic Review 105(2): 609-645.