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Brief 18: Does a Mexican healthcare program really help the poor?

Researchers developed a field experiment within a program that aimed to deliver health insurance to uninsured Mexicans. They found that the program reduced overall catastrophic and out-of-pocket expenditures for inpatient & outpatient procedures.

Link to Full Study

Category: Public Service Provision

Date of Publication: Wednesday, March 25, 2015

EGAP Researcher: Ryan Moore, Kosuke Imai

Other Authors: Gary King, Emmanuela Gakidou, Héctor Hernández Llamas, Jason Lakin, Mauricio Hernández Ávila, Clayton Nall, Nirmala Ravishankar, Manett Vargas, Martha María Téllez-Rojo, Juan Eugenio Hernández Ávila

PDF: PDF icon Brief-18-moore-seguro-popular.pdf

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Geographical Region: North America

Research Question:

Mexico’s universal health care program, Seguro Popular, aimed to reduce the prevalence of catastrophic health costs amongst the poor. Was it successful?

Preparer: Damaris Colhoun



The study is notable as being the first of its kind: no country pursuing a health care model like Seguro Popular has ever been assessed in a large-scale randomized scientific study such as this. Noting that many public policy experiments get “torpedoed by politicians” who are concerned about the short-term desires of their constituents, “such as those who wind up in control groups without new services,” the researchers designed this experiment to survive such political missiles. By building their evaluation into a “real world” program that was backed by the Mexican government, and in the process of being implemented, the researchers were able to make randomization politically and ethically feasible, since all the control groups could enroll in Seguro Popular, even before the “treatment.”

Research Design:

The experiment randomly determined who received the treatment, this group is called the “treatment cluster” and who did not, called the “control cluster.” The households living within the treatment clusters were encouraged to apply for the health care package, while families living within the control clusters were offered nothing extra, and stayed with the usual for-pay care. Researchers surveyed 32,515 households in the initial survey, gathering spending data from the head of household, individual data from a randomly selected adult, and assessing whether or not they had signed up for Seguro Popular. In the follow-up survey ten months later, the researchers interviewed 29,897 households, with a focus on expenditures. The researchers measured those expenditures by annualizing the head of households’ self-reported, out-of-pocket health spending based on the previous 1-3 months. If a household’s health spending is 30% or more of its annual budget, minus the cost of basic necessities such as food and water, etc., it was defined as catastrophic.

More than half of the communities that participated in the study were poor. Out of households surveyed, 55% were defined as high asset, meaning they had at least half of the following items: non-dirt floor, electricity, washing machine, gas stove, phone, and other amenities.

The researchers identified one notable pattern that indicated bias: in the pretreatment survey, the poor tended to report that they were slightly healthier, and the rich that they were sicker, than those in the control group. This could be have been due to random chance, or a placebo-like effect.


Some of the results were surprising. For instance, researchers found that in the control clusters, a small number of households did enroll in the program, whereas many individuals in the treatment clusters chose not to enroll at all. Results cut across income lines as well, by suggesting that “treatment assignment” was much more effective in poorer areas than richer ones. Yet this pattern did not hold true for individual households: those with more assets living in poor areas were as likely to enroll in Seguro Popular as their poorer neighbors.

As for expenditures, researchers found that 8.4% of all the control groups spent more than 30% of their annual income on health in the past year, whereas for those who enrolled, Seguro Popular reduced the proportion of the catastrophic expenditures by 55%, with most of the effect occurring in poorer households. During the ten month assessment period, Seguro Popular reduced catastrophic expenditures for all by 23%. These findings suggest that Seguro Popular has been successful in reducing overall catastrophic and out-of-pocket expenditures for inpatient and outpatient procedures, especially among the poor. What’s more, Mexico may now have a scientifically validated system for delivering health services to its poorest citizens.


Policy Implications:
  • As the first large scale randomized scientific assessment of a national health care program, this study may also be a model for other countries that want to pursue a similar evaluation model for their own health care programs.
  • Finally, policy makers and community health care workers ought to consider this study’s finding that a household’s decision to enroll in a given health care plan may have less to do with household income than with broader community attitudes.