International audienceBACKGROUND - In France, the national health database (SNIIRAM) is an administrative health database that collects data on hospitalizations and healthcare consumption for more than 60 million people. Although it does not record behavioral and environmental data, these data have a major interest for epidemiology, surveillance and public health. One of the most interesting uses of SNIIRAM is its linkage with surveys collecting data directly from persons. Access to the SNIIRAM data is currently relatively limited, but in the near future changes in regulations will largely facilitate open access. However, it is a huge and complex database and there are some important methodological and technical difficulties for using it du...