Funding for this research was provided by:
Instituto de Salud Carlos III (RD16/0001/0007)
Text and Data Mining valid from 2018-09-10
Received: 13 April 2018
Accepted: 3 August 2018
First Online: 10 September 2018
Ethics approval and consent to participate
: This study, observational in design, used retrospective pseudonymised data, and was conducted in accordance with the amended Helsinki Declaration, the International Guidelines for Ethical Review of Epidemiological Studies, and Spanish laws on data protection and patients’ rights. This study implies the use of pseudonymised individual data, using double dissociation (i.e., in the original data source and once data are stored in the database) which impedes patients re identification<b>.</b>
: Not applicable.
: The authors declare that they have no competing interests. Enrique Bernal-Delgado is currently acting as associate editor of BMC Health Services Research.
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