Funding for this research was provided by:
Universidad Nacional Autónoma de México (Support Program for Graduate Studies 2017)
Instituto Mexicano del Seguro Social (FIS/IMSS Prot MD17/1688)
Text and Data Mining valid from 2019-01-10
Received: 14 June 2018
Accepted: 4 December 2018
First Online: 10 January 2019
Compliance with ethical standards
: The authors have no financial or any other kind of personal conflicts with this paper.
: The National Committee of Scientific Research approved the study (R-2016-785-074). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: Written informed consent was obtained from all participants included in the study. Written informed consent was approved by the National Committee of Scientific Research.