The roll-out of a health insurance program and its impact on the supply of healthcare services: a new method to evaluate time-varying continuous interventions.

BACKGROUND: We analyze the effects of the Mexican universal health insurance program, Seguro Popular, on key variables associated with the provision of healthcare services. Given that the program was introduced gradually over a period that lasted more than a decade, the dynamics of the roll-out of the program and its reaction to the expansion of healthcare services it caused should be accounted for when evaluating the program.

METHODS: We present a new semiparametric procedure to analyze time-varying continuous interventions. This is accomplished by bringing together the literatures on continuous and on dynamic treatments. Our approach allows the researcher to estimate mean and quantile dose-response functions by applying local regression methods to appropriately weighted samples that control for time-dependent confounding.

RESULTS: Using administrative data, we show compelling evidence that Seguro Popular has incremented the human and physical resources available for healthcare services over the period 2001-2013. Moreover, we show that these effects have been heterogeneously distributed.

CONCLUSIONS: The program has proven most helpful in less vulnerable territories, leaving behind those in greater need.