Article History
Received: 6 November 2018
Accepted: 4 March 2019
First Online: 18 March 2019
Ethics approval and consent to participate
: For this type of retrospective study formal consent is not required; any personal data was protected accordingly to the Helsinki Declaration and to the Italian law (Legislative Decree of 30 June 2003, n. 196. Code on the protection of personal data).
: Non applicable.
: The authors declare that they have no competing interests.
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