Funding for this research was provided by:
Received: 29 May 2018
Accepted: 27 August 2018
First Online: 29 September 2018
Ethics approval and consent to participate
: Ethical approval was granted by the Medical Ethical Committee of the Leiden University Medical Center (CME-V006). The need for informed consent was waived in view of the observational character of the study.
: Not applicable.
: The authors declare that they have no competing interests.
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