Background:

The Spanish Health Survey (SHS) is one of the main sources on social determinants of health. The objectives were to describe the data merging process of the 2006/07 and 2011/12 SHS editions, as well as to provide the merged databases and the directory of the variables.

Methods:

The comparable variables were identified from the questionnaires. Other new variables were created to achieve comparability or to provide new indicators of interest. We obtained two completed merged databases, as well as two variable directories with their dictionaries (each one for the adults and children samples).

Results:

188 variables were identified as potentially comparable ones. 36,7% of them had difficulties for being comparable and 8% had to be removed. The topic with the worst consequences due to the lack of comparability was the working conditions and employment from the adult sample.

Conclusion:

The merging of both SHS editions had a lot of problems, especially in the adult’s sample. That affects to its comparability. This work may be useful to assess, design and merge these and other editions of the SHS, as well as to serve as a model to be applied in other cross-sectional population-based surveys.

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