[The value of using administrative data in public health research: the Continuous Working Life Sample].

The use of administrative data is common practice in public health research. The present field note describes the Continuous Working Life Sample (CWLS) and its use in health research. The CWLS is built on records generated by all contacts with the social security system (work contracts, disability, etc.), plus tax data (monetary gains, income, etc.) and census data (level of education, country of birth, etc.), but does not allow individuals to be identified. The CWLS was started in 2004 with 4% (1.1 million persons) of the total population who were either contributors to or beneficiaries of the social security system. The information on the individuals in the CWLS is updated annually and lost individuals are replaced. This continuous design allows the construction of a cohort with information on working life and financial status and evaluation of their relationship with work disability. Future connection with clinical records would enable analysis of other health-related outcomes.