Funding for this research was provided by:
Horizon 2020 (No 690984: DEMOSTAF project)
Received: 18 May 2018
Accepted: 22 July 2019
First Online: 29 July 2019
Ethics approval and consent to participate
: Ethical concerns regarding the free and informed consent of participants are not relevant here as the study participants are deceased persons. Ethical clearance was not sought because the dataset used for this study does not contain any identifiable information of study participants. Researchers involved in this study had no access to the registers themselves; they only had access to the anonymous database.
: Not applicable
: The authors declare that they have no competing interests.