Frequency of health-care service use and severity of illness in undocumented migrants in Catalonia, Spain: a population-based, cross-sectional study.

Background: In Spain, legislation was passed in 2012 excluding undocumented migrants from the public health-care system. Catalonia was one of the Spanish regions that did not implement this legislation, and continued to guarantee access to health care to the whole population. We aimed to analyse health-care use and health status among undocumented migrants in Catalonia, and compare health-care use and health status with legal residents classified according to their socioeconomic position (SEP).